M50 cranks but won't fire

[bissellh]

My 1992 BMW E34 525i with M50 non vanos engine will not start. The symptoms: The check engine light does not illuminate at all preventing me from doing a stomp test. The engine does turn over, but does NOT fire or start.

The last time I drove it, some lights on the speedo were flickering. The ABS and check engine light flickered. The engine actually cut out momentarily
on the highway, but started up again without having to pull over.

Just to make things more complicated, here are some things I did to the car recently:
1. replaced fuel pump and fuel level sensor. This seemed to impove engine performance. The engine had been stuttering while pulling away from stop lights. The fuel pressure must have been low. The gas gauge had been flaky. The new fuel level sender seems to have improved this behavior, but I have not been able to run the gas low in the tank in order to test this since the car will not start anymore.
2. I wired an electic inverter directly to the battery under the back seat so I can charge my electric golf push cart battery on the way home from the golf course. It has automatic shut off in case the battery gets low. Plus, I have one of those voltage regulators bolted on there. I hope I did not damage any of my electronics with this thing.
3. I switched out the master and slave brake cylinders recently and got some air in the ABS unit along the way. I have not had time to take it in to get this resolved yet. I hope the ABS is not sending some sort of kill signal to the ECU.

These 3 things probably have nothing to do with anything. I suspect that my ECU/DME/Motronic is bad, but I am not sure. My car is so flaky, I usually think the engine harness needs replacing when something quirky starts going on, like the speedo lights start flashing. I guess this can be expected from time to time since my car is a 1992 with 250K miles and is parked outside in the elements.

Has anyone had similar symptoms? If so, do you how I can narrow down the problem?

[glen-sj]

I had the same symptom, and it turned out to be a bad fuel pump. But you said you replaced the fuel pump. So I would look into the fuel pump relay and the Crank Position Sensor.

[Dave M]

If you're confident the pump is working (do a search on how to verify), get 'old school' and pull a plug/coil to check for spark. If you have spark get a multimeter and test the Crank Position Sensor. The specs are in the Bentley or here if you ask. The speedo guage lights flickering makes me think something like a fusible luink might be at fault (need to know where your batt. is to find teh link).

More info = more answers. Keep us updated.

DAveM

[bissellh]

I had the same symptom, and it turned out to be a bad fuel pump. But you said you replaced the fuel pump. So I would look into the fuel pump relay and the Crank Position Sensor.

I did replace the fuel pump, but is was a used one. After my car stopped running, I swapped out the fuel pump relay with a spare I had. That did not help. Maybe I better jump the fuel pump relay socket to see if the fuel pump winds up. I bet my repair manual has information on how to do that. it probably also has information on the crank position sensor test.

[bissellh]

If you're confident the pump is working (do a search on how to verify), get 'old school' and pull a plug/coil to check for spark. If you have spark get a multimeter and test the Crank Position Sensor. The specs are in the Bentley or here if you ask. The speedo guage lights flickering makes me think something like a fusible luink might be at fault (need to know where your batt. is to find teh link).

More info = more answers. Keep us updated.

DAveM

I know how to jump the fuel pump, check for spark and I think I can find crank position sensor testing information in my repair manual. I am not sure what the fusible link is, but my battery is under the back seat on the passenger side. Is there a fuse in there I need to check. Maybe the inverter I wired to my battery is causing my problems.

[bissellh]

If you're confident the pump is working (do a search on how to verify), get 'old school' and pull a plug/coil to check for spark. If you have spark get a multimeter and test the Crank Position Sensor. The specs are in the Bentley or here if you ask. The speedo guage lights flickering makes me think something like a fusible luink might be at fault (need to know where your batt. is to find teh link).

More info = more answers. Keep us updated.

DAveM

I just went out and jumped posts 30 and 87 on the fuel pump relay. On my 1992 525i E34 it is the middle one, the blue one in the set of three in between the engine and ABS ECU's under the cover in the front right area of the engine compartment. At least I hope that is the fuel pump relay. I did not hear any sounds from the fuel pump or any sounds of fuel running through the lines. However, I squeezed the rubber fuel line hoses that connect the rail to the metal lines. I could barely squeeze the one at the front of the engine because it is full of pressure. While I could fully compress the one at the back of the engine. Does anyone know which is the supply and which is the return? I imagine the front is the supply. Could this mean my fuel rail or regulator is clogged? Perhaps I dredged up some stuff in the fuel tank while changing fuel pumps. Actually I pulled up some metal from the fuel tank with a magnet and scooped out some dredge with a fine filter while I was swapping fuel pumps. Does this pressure difference mean anything?

I am planning on relieving some of that pressure tomorrow by allowing some fuel out and trying this test again.

[whiskychaser]

I just went out and jumped posts 30 and 87 on the fuel pump relay. On my 1992 525i E34 it is the middle one, the blue one in the set of three in between the engine and ABS ECU's under the cover in the front right area of the engine compartment. At least I hope that is the fuel pump relay. I did not hear any sounds from the fuel pump or any sounds of fuel running through the lines. However, I squeezed the rubber fuel line hoses that connect the rail to the metal lines. I could barely squeeze the one at the front of the engine because it is full of pressure. While I could fully compress the one at the back of the engine. Does anyone know which is the supply and which is the return? I imagine the front is the supply. Could this mean my fuel rail or regulator is clogged? Perhaps I dredged up some stuff in the fuel tank while changing fuel pumps. Actually I pulled up some metal from the fuel tank with a magnet and scooped out some dredge with a fine filter while I was swapping fuel pumps. Does this pressure difference mean anything?

I am planning on relieving some of that pressure tomorrow by allowing some fuel out and trying this test again.
The fuel pump relay is the middle one of 3 in the e-box. May be worth checking you actually have a voltage at the pins and then at the pump before you start ripping the pump out again. The fuel goes in the front (radiator) end of the rail and the pressure regulator is at the back. The hoses are pretty solid - especially if they are old -so a finger and thumb pressure test wont really do. To save you looking it up, you should have 51psi fuel pressure with engine off and jumper in place. Im not going into why but this will drop to about 43 with the engine running. HTH

[glen-sj]

When you performed the jumper test on the pump relay. Did you also checked to see if any voltage at the fuel pump?

[outomoneyracer]

My 1992 BMW E34 525i with M50 non vanos engine will not start. The symptoms: The check engine light does not illuminate at all preventing me from doing a stomp test. The engine does turn over, but does NOT fire or start.

The last time I drove it, some lights on the speedo were flickering. The ABS and check engine light flickered. The engine actually cut out momentarily
on the highway, but started up again without having to pull over.

Just to make things more complicated, here are some things I did to the car recently:
1. replaced fuel pump and fuel level sensor. This seemed to impove engine performance. The engine had been stuttering while pulling away from stop lights. The fuel pressure must have been low. The gas gauge had been flaky. The new fuel level sender seems to have improved this behavior, but I have not been able to run the gas low in the tank in order to test this since the car will not start anymore.
2. I wired an electic inverter directly to the battery under the back seat so I can charge my electric golf push cart battery on the way home from the golf course. It has automatic shut off in case the battery gets low. Plus, I have one of those voltage regulators bolted on there. I hope I did not damage any of my electronics with this thing.
3. I switched out the master and slave brake cylinders recently and got some air in the ABS unit along the way. I have not had time to take it in to get this resolved yet. I hope the ABS is not sending some sort of kill signal to the ECU.

These 3 things probably have nothing to do with anything. I suspect that my ECU/DME/Motronic is bad, but I am not sure. My car is so flaky, I usually think the engine harness needs replacing when something quirky starts going on, like the speedo lights start flashing. I guess this can be expected from time to time since my car is a 1992 with 250K miles and is parked outside in the elements.

Has anyone had similar symptoms? If so, do you how I can narrow down the problem?
My 530 stumped me for couple of days when it wouldn't start. I tested and knew I had no spark and thought I had gas but was wrong and chased my tale. Make sure if you have gas or not going to the motor. Easy way to tell if you have juice going to fuel pump is turn on key and chek for voltage at the fuel pump fuse under the hood. If no juice to feul pump fuse and no juice to coils(no spark) then its probably the main relay located in box at right rear of engine compartment. $25 at the dealer

[shogun]

I had a similar case on an E32 750 last Saturday. One side of the V12 was not running.
I by-passed all the fuel relais etc and used the battery post under the hood and connected a test probe directly to fuse 22 and 23, which are the fuses for the 2 fuel pumps on the 750. I could hear both running, but one was making much more 'noise' and I could even feel the fuel running thru the hose in engine room and back thru the return line. The other pump also might a smlight humming noice, but was much to weak to produce the power to pump the required volume and pressure.
That is the second time now that I helped someone out with bad fuel pumps, and in both cases they bought used ones and in both cases the used ones were bad!

[bissellh]

My 1992 BMW E34 525i with M50 non vanos engine will not start. The symptoms: The check engine light does not illuminate at all preventing me from doing a stomp test. The engine does turn over, but does NOT fire or start.

The last time I drove it, some lights on the speedo were flickering. The ABS and check engine light flickered. The engine actually cut out momentarily
on the highway, but started up again without having to pull over.

Just to make things more complicated, here are some things I did to the car recently:
1. replaced fuel pump and fuel level sensor. This seemed to impove engine performance. The engine had been stuttering while pulling away from stop lights. The fuel pressure must have been low. The gas gauge had been flaky. The new fuel level sender seems to have improved this behavior, but I have not been able to run the gas low in the tank in order to test this since the car will not start anymore.
2. I wired an electic inverter directly to the battery under the back seat so I can charge my electric golf push cart battery on the way home from the golf course. It has automatic shut off in case the battery gets low. Plus, I have one of those voltage regulators bolted on there. I hope I did not damage any of my electronics with this thing.
3. I switched out the master and slave brake cylinders recently and got some air in the ABS unit along the way. I have not had time to take it in to get this resolved yet. I hope the ABS is not sending some sort of kill signal to the ECU.

These 3 things probably have nothing to do with anything. I suspect that my ECU/DME/Motronic is bad, but I am not sure. My car is so flaky, I usually think the engine harness needs replacing when something quirky starts going on, like the speedo lights start flashing. I guess this can be expected from time to time since my car is a 1992 with 250K miles and is parked outside in the elements.

Has anyone had similar symptoms? If so, do you know how I can narrow down the problem?

I went to my car this evening after work armed with tools, including an electrical meter, determined to find the problem with my car. Here is what happened.

I first noticed that I was getting a solid red check engine light when I turned the key to position 2. Since my car stopped running on Sunday, the check engine light would not always illuminate after turning key to position 2. I did the stomp test and got code 1000. But, I did not try to start the engine, thinking there is no way it could fix itself.

I decided to go old school and check for spark first. I pulled a plug and asked my trusty asistant to turn the engine over. To my suprise, the spark plug sparked and shocked me. The damn car started and I dropped the plug on the ground. I was thinking about putting my volt meter on the coil with out the plug. But, like I said, I was going old school. Hah!

I obviously have spark and fuel now. I noticed that the fuel pressure in the segment of rubber fuel hose going INTO the engine was not as pressurized at is was last night. It is as if there was a clog and it let loose.

I did another stomp test and got code 1444. I restrted the car a few times to make sure I was not imagining it running.

I do not know what is going on with this car. Perhaps it has gremlins.

[Dave M]

I went to my car this evening after work armed with tools, including an electrical meter, determined to find the problem with my car. Here is what happened.

I first noticed that I was getting a solid red check engine light when I turned the key to position 2. Since my car stopped running on Sunday, the check engine light would not always illuminate after turning key to position 2. I did the stomp test and got code 1000. But, I did not try to start the engine, thinking there is no way it could fix itself.

I decided to go old school and check for spark first. I pulled a plug and asked my trusty asistant to turn the engine over. To my suprise, the spark plug sparked and shocked me. The damn car started and I dropped the plug on the ground. I was thinking about putting my volt meter on the coil with out the plug. But, like I said, I was going old school. Hah!

I obviously have spark and fuel now. I noticed that the fuel pressure in the segment of rubber fuel hose going INTO the engine was not as pressurized at is was last night. It is as if there was a clog and it let loose.

I did another stomp test and got code 1444. I restrted the car a few times to make sure I was not imagining it running.

I do not know what is going on with this car. Perhaps it has gremlins.

Perhaps........... ;)

If you did have an obstruction in your fuel line, hopefully it has made the loop back to the tank and will sit there benignly. I wouldn't guess something large enough to clog a line would have originated in the tank (fuel filters etc.), so either something enetered the line while a repair was done, or your fuel pressure regulator is faulty????

Anyhow, glad it started, knnock on wood and hope your luck continues.

Dave

[bissellh]

Perhaps........... ;)

If you did have an obstruction in your fuel line, hopefully it has made the loop back to the tank and will sit there benignly. I wouldn't guess something large enough to clog a line would have originated in the tank (fuel filters etc.), so either something enetered the line while a repair was done, or your fuel pressure regulator is faulty????

Anyhow, glad it started, knnock on wood and hope your luck continues.

Dave

I tooks my car on an errand tonight and filled it up with gas

[bissellh]

Perhaps........... ;)

If you did have an obstruction in your fuel line, hopefully it has made the loop back to the tank and will sit there benignly. I wouldn't guess something large enough to clog a line would have originated in the tank (fuel filters etc.), so either something enetered the line while a repair was done, or your fuel pressure regulator is faulty????

Anyhow, glad it started, knnock on wood and hope your luck continues.

Dave

I tooks my car on an errand tonight and filled it up with gas and put in some injector cleaner in case it needs it. On the way home, the cut out, but only for a second or less. At the same time two lights on the speedo flickerd. They were the antilock and parking brake lights. I was able to restart my car when I arrived home.

Now it feels more like an electrical problem of sorts. It could be the crank position sensor that someone mentioned befoe. It could be the ECU. It could be the alternator. It could be a shoted, loose, burnt wire somewhere.

Does anyone have an opinion? I am trying to locate the crank position sensor in order to test. I could go by my local parts store so they could test my alternator.

[whiskychaser]

I tooks my car on an errand tonight and filled it up with gas and put in some injector cleaner in case it needs it. On the way home, the cut out, but only for a second or less. At the same time two lights on the speedo flickerd. They were the antilock and parking brake lights. I was able to restart my car when I arrived home.

Now it feels more like an electrical problem of sorts. It could be the crank position sensor that someone mentioned befoe. It could be the ECU. It could be the alternator. It could be a shoted, loose, burnt wire somewhere.

Does anyone have an opinion? I am trying to locate the crank position sensor in order to test. I could go by my local parts store so they could test my alternator.
The CPS is item 9 here:
http://www.realoem.com/bmw/showparts.do?model=HD68&mospid=47405&btnr=11_0157&hg=11&fg=10
Well its not item 9 'cos thats the wire - its the bit at the end:) If you put a meter across your battery with the engine running and you get 13.8vdc (a bit more on some) your alternator isnt the problem. I can understand why the ABS would come on if the engine stopped but not the brake warning - thats normally your handbrake is on or your brake fluid is low. Test the bits you can do in a logical sequence. Unless you have some audio system out of Pimp My Ride or something, I doubt you have a shorted, burned or loose wire:)

[bissellh]

My 1992 BMW E34 525i with M50 non vanos engine will not start. The symptoms: The check engine light does not illuminate at all preventing me from doing a stomp test. The engine does turn over, but does NOT fire or start.

The last time I drove it, some lights on the speedo were flickering. The ABS and check engine light flickered. The engine actually cut out momentarily
on the highway, but started up again without having to pull over.

Just to make things more complicated, here are some things I did to the car recently:
1. replaced fuel pump and fuel level sensor. This seemed to impove engine performance. The engine had been stuttering while pulling away from stop lights. The fuel pressure must have been low. The gas gauge had been flaky. The new fuel level sender seems to have improved this behavior, but I have not been able to run the gas low in the tank in order to test this since the car will not start anymore.
2. I wired an electic inverter directly to the battery under the back seat so I can charge my electric golf push cart battery on the way home from the golf course. It has automatic shut off in case the battery gets low. Plus, I have one of those voltage regulators bolted on there. I hope I did not damage any of my electronics with this thing.
3. I switched out the master and slave brake cylinders recently and got some air in the ABS unit along the way. I have not had time to take it in to get this resolved yet. I hope the ABS is not sending some sort of kill signal to the ECU.

These 3 things probably have nothing to do with anything. I suspect that my ECU/DME/Motronic is bad, but I am not sure. My car is so flaky, I usually think the engine harness needs replacing when something quirky starts going on, like the speedo lights start flashing. I guess this can be expected from time to time since my car is a 1992 with 250K miles and is parked outside in the elements.

Has anyone had similar symptoms? If so, do you how I can narrow down the problem?

Drove my car the next day to work. it worked fine. On the way home from work it stalled on me a few times. Like I said, the problem is sporadic. Anyway, thanks to the last post with the diagram of the CPS, showing what it looks like and where it is located, I was able to replace the CPS. I am familiar with realoem.com, but was not able to find that diagram. I had a used CPS lying around from a harness I bought off a salvage car. Now, it is running much better and is not stalling. The old CPS was in really bad shape. There were about three breaks in the rubber wire coating. It looked like the wire had been partially pulled away from the sensor. Plus, the plug that connects to the harness was partially melted. I will keep this post open for a few days to make sure that resolved the problems before I close it. Thanks again for all the help!

[attack eagle]

Fusible links replaced?

[Ross]

Electrical I say. Have good look at the fusible links.

[bissellh]

Fusible links replaced?

I have been driving my car for the last week with no cutting out or stalling engine problems. The crank position sensor (CPS) was indeed the problem. My engine sounds and performs better. It is a little early to tell, but I think it is using less gas than before I switched out the sensor. Thanks for all of your help. This thread can be closed/archived. I do not know if I do that or if someone else does.

[bissellh]

I have been driving my car for the last week with no cutting out or stalling engine problems. The crank position sensor (CPS) was indeed the problem. My engine sounds and performs better. It is a little early to tell, but I think it is using less gas than before I switched out the sensor. Thanks for all of your help. This thread can be closed/archived. I do not know if I do that or if someone else does.

My car is very frustrating. My car started cutting out and will not start at all now. The check engine light will not illuminate for a stomp test. I do not have gas going to the engine. I tested power at all the appropriate posts on the motronic and fuel pump relays for power - OK. I tested the relays themselves - OK. I jumped the fuel pump relay socket and got power at fuse 23 and at my conector to the fuel pump. I tested the fuel pump independently and it works, but it will not start while installed in my car. Do I need more than power to the fuel pump to make it run. Does anyone know why it does not run the fuel pump? Does anyone know what would cause the stomp test not to work anymore?

[genphreak]

My car is very frustrating. My car started cutting out and will not start at all now. The check engine light will not illuminate for a stomp test. I do not have gas going to the engine. I tested power at all the appropriate posts on the motronic and fuel pump relays for power - OK. I tested the relays themselves - OK. I jumped the fuel pump relay socket and got power at fuse 23 and at my conector to the fuel pump. I tested the fuel pump independently and it works, but it will not start while installed in my car. Do I need more than power to the fuel pump to make it run. Does anyone know why it does not run the fuel pump? Does anyone know what would cause the stomp test not to work anymore?M50 = tons of potential places for air leaks, you have to religously get to all hoses and connections that link into the intake manifold (hrd to see them and get to them)... the o-rings on the connectors, the pipes and the connector locks, are major areas for analysis. I'd done them all until I relaised the FPR line was a bit hardened... causing no end of sporadic troubles.

Have you ever heard it backfire inside the intake? (a sure sign on an M50 of intake leaks)

[bissellh]

M50 = tons of potential places for air leaks, you have to religously get to all hoses and connections that link into the intake manifold (hrd to see them and get to them)... the o-rings on the connectors, the pipes and the connector locks, are major areas for analysis. I'd done them all until I relaised the FPR line was a bit hardened... causing no end of sporadic troubles.

Have you ever heard it backfire inside the intake? (a sure sign on an M50 of intake leaks)

I went through the whole vacumm thing late last year. No backfire because no fuel.

I can not get my check engine light to illuminate for the stomp test to read codes and I have no gas pressure despite testing all the points for power after jumping the fuel pump relay socket.

Any ideas?

How can I retest the installed fuel pump? Does anyone know which of the 5 or so pins to suplly power to and which of the pins to supply ground to to run the fuel pump? I could run the pump by jumping power directly to it and them see if it will start?

[Dave M]

How can I retest the installed fuel pump? Does anyone know which of the 5 or so pins to suplly power to and which of the pins to supply ground to to run the fuel pump? I could run the pump by jumping power directly to it and them see if it will start?

Which end are you referring to? At the fuel pump end, Bentley manual clearly defines the wires.

I've been through this in the past, but I can't find the thread.

I'd say the brown wire is power if I had to...

Dave

[bissellh]

Which end are you referring to? At the fuel pump end, Bentley manual clearly defines the wires.

I've been through this in the past, but I can't find the thread.

I'd say the brown wire is power if I had to...

Dave

I want to jumper power to the fuel pump directly to the plug into the fuel pump itself. In my 1992 BMW 525i E34 M50 the fuel pump is next to the spare in the trunk just below the trunk floor surface inside the gas tank. There are actually six pins coming out of the plug into the fuel pump. Some are probably for fuel level signals. I am trying to figure out which one is for positive 12V and which one is for ground to make the fuel pump go. I do not want to experiment with combinations of the pins so as not to damage anything.

[Bellicose Right Winger]

I'm not sure exactly where you are with your testing, but here are my thoughts.

Spark is the key. If you still have a spark then crank position sensor/DME/main relay are working fine. FP relay won't energize if these three aren't working.

Do you have the ETM for car?. It's can be downloaded from many places. http://pdftown.com/PDF-BMW-E34-1988-1995-Electronic-Troubleshooting-Manual.html

Forget about the codes and reinstall the jumper at fuel pump relay. There's a schematic diagram on relay, you should jump pins 30 and 87. If FP doesn't run check fuse and probe to chassis ground for 12 volts at fuel pump connector.

Paul Shovestul
BMW CCA 69606

http://www.bimmernut.com/forum/showthread.php?t=1834&page=2&highlight=shovestul+fuel+relay

[Dave M]

http://img.photobucket.com/albums/v11/dave_macisaac/Bimmer/Fuel%20Pump/DSC00514.jpg

If I recall correctly, power is the green/violet one in my drooring. When in doubt, jumper the relay and use your dmm to find the power (assuming its getting there).

If you've got power and you can't hear the pump running, time for a new pump.

Dave

[Monastie]

make sure you routed the cps wire correctly, it's a bit weird but it'll prevent it from getting cut by the coolant pump's belt.

I have a fuel pump if you end up needing one.

[bissellh]

make sure you routed the cps wire correctly, it's a bit weird but it'll prevent it from getting cut by the coolant pump's belt.

I have a fuel pump if you end up needing one.

I went out and checked for voltage to fuel pump. There is voltage, but only 3volts. I get three volts with the relay jumpered or with the relay installed and the ignition on. That is not enough to run the fuel pump. I jumpered the fuel pump off the battery to run it, but the car still would not start.

I have a spare ECU that I swapped out to see if it would make any difference. My car has a 402 and my spare is a 403. It did not make any difference.

I still can not get the stomp test to work. So, I tested the throttle positon sensor. The resistance across pin 1 and 3 of the sensor itself is good. However, there is not 5 volts at pin 1 of the connector, as my Chilton repair says there should be.

I also rechecked for spark, but forgot to pull the plug. I only pulled the coil. I do not think that should show any noticeable spark.

Anyway, I more concerned about the low voltage to my fuel pump and no voltage to the throttle position sensor.

Any ideas...

[bissellh]

What's your battery reading now?


My battery is now dead as my car has not run for over a week and I have been trying different things to start it. I have to jump the battery with my truck to try to start it. I measured the voltage on the post where I am jumping the battery as 12 volts, but did not measure anyplace else. Would anyone recommend another place to test for 12 volts while I have the car jumped?

[Morgenster]

What's your battery reading now?

[bissellh]

OK, 3V out of the power wire to the pump harness if a definite issue (and one I'm not qualified to help with). Are you absolutely certain you're testing the proper pin on the harness?

Now, when you say you jumped the pump with 12V, I'm assuming you got a good 12V to the power pin on the pump harness in the trunk AND maintained a good ground. Am I correct? What I haven't heard you say (type), is whether you heard the pump running when you provided a good 12V to it. If you didn't, then it goes without saying that the vehicle won't start AND, that the pump has quit working. Now, if you heard the pump running when you got 12V to it, but the car wouldn't start, then its back to looking for spark etc. I'm confused ;).


The engine will start even when the tps is disconnected.

You might want to try checking for spark with the plug attached.

Dave

Yes, the fuel pump was running when I jumped it to the positive post under the hood and grounded it. I could hear the fuel pump running and I could hear the fuel going through the fuel rail. I definitely had fuel. I will recheck for spark tonight, this time pulling the coil and plug, not just the coil.

[Dave M]

I went out and checked for voltage to fuel pump. There is voltage, but only 3volts. I get three volts with the relay jumpered or with the relay installed and the ignition on. That is not enough to run the fuel pump. I jumpered the fuel pump off the battery to run it, but the car still would not start.
I have a spare ECU that I swapped out to see if it would make any difference. My car has a 402 and my spare is a 403. It did not make any difference.

I still can not get the stomp test to work. So, I tested the throttle positon sensor. The resistance across pin 1 and 3 of the sensor itself is good. However, there is not 5 volts at pin 1 of the connector, as my Chilton repair says there should be.

I also rechecked for spark, but forgot to pull the plug. I only pulled the coil. I do not think that should show any noticeable spark.

Anyway, I more concerned about the low voltage to my fuel pump and no voltage to the throttle position sensor.

Any ideas...


OK, 3V out of the power wire to the pump harness if a definite issue (and one I'm not qualified to help with). Are you absolutely certain you're testing the proper pin on the harness?

Now, when you say you jumped the pump with 12V, I'm assuming you got a good 12V to the power pin on the pump harness in the trunk AND maintained a good ground. Am I correct? What I haven't heard you say (type), is whether you heard the pump running when you provided a good 12V to it. If you didn't, then it goes without saying that the vehicle won't start AND, that the pump has quit working. Now, if you heard the pump running when you got 12V to it, but the car wouldn't start, then its back to looking for spark etc. I'm confused ;).


The engine will start even when the tps is disconnected.

You might want to try checking for spark with the plug attached.

Dave

[Dave M]

Yes, the fuel pump was running when I jumped it to the positive post under the hood and grounded it. I could hear the fuel pump running and I could hear the fuel going through the fuel rail. I definitely had fuel. I will recheck for spark tonight, this time pulling the coil and plug, not just the coil.


From Bellicose's previous post:


Spark is the key. If you still have a spark then crank position sensor/DME/main relay are working fine. FP relay won't energize if these three aren't working.

If this is correct and you don't have spark, you may be on the right path.

Dave

[bissellh]

From Bellicose's previous post:



If this is correct and you don't have spark, you may be on the right path.

Dave

I tested for spark tonight and there is none. Swapping my 402 ECU with a spare 403 ECU I have had no effect.

I also tested post 30 on the fuel pump relay socket. The reason that there is only 3 volts coming out of the fuel pump relay is because there is only 3 volts going into it on post 30. This situation is not unique to the fuel pump relay. There was also only 3 volts going to the other 3 relays.

I have no voltage going to the throttle position sensor. There was 12 volts to the + post under the hood while jumping the car.

I am not sure what is causing this. It may be something defective with my wiring or something else.

I do have a voltage regulator and an inverter bolted to the posts of my battery. Perhaps one of them is malfunctionaing and causing low voltage. I do not know where the voltage to the relays comes from. I don't know if it comes direct from the battery or through some other circuitry.

Any ideas?

[genphreak]

No spark, no fuel pump feed (to speak of)... etc.

I hate to be the sayer of bad news, but... this screams DWA or EWS issues.

Work out (search the web) for the kind of EWS (1 or II) you have. If your battery has gone down/been disconnected, the ECU may not be in sync with the ECS unit, or the EWS may be activated (immobilising the car by not sending the ECU the 'good to go' code). In this case, nothing happens. The dealer can resync the EWS to the ECU on their Modic unit, and so can an Autologic. Carsoft 6.5 claims to do it but I don't know if it works on EWS II- probably does on EWS I. This often comes with the $100 Chinese scanners on available on the Bay.

But it may also be the DWA (Drive Away Protection) is triggered... that means a shogun reset- if that doesn't work- the dealer may be the only option other than replacing the EWS unit (or matching EWS and ECU if you have EWS II) from a breaker... It may be worth getting a dealer to put it on theirs (paid by the hour), and get them to tell you what is what. One scan will take them 10 mins tops. You can always go get a new ECU and EWS and get them to install it if it ends up being that bad (but it shouldn't)


The very best of luck... :) Nick

If you think this could be it, look for info on EWS and DWA over at e38.org and the links pages at bimmerboards.com

[Dave M]

Did you ever find / check the fusible link?

Just curious,

Dave

[Bellicose Right Winger]

3 volts at post 30 with 12 volts at battery....... Now you're on to something. If engine cranks ok then inverter isn't a problem. Post 30 is directly connected to battery according to page 0670.2.00 in the ETM. The fusable link doesn't come into play and I'm sure a '92 is too old for EWS or DWA. Inspect/check connections at battery and starter. You'll have to follow the wire from post 30 back toward the battery to find the problem. ETM shows (2) splices in wire between post 30 and battery.

You could run a FUSED jumper from + battery terminal to post 30, reinstall FP relay and see if car starts.

Edit: On second thought....if inverter is spliced into wire that feeds post 30 and that connection has failed, then it could be the problem. Check connections and/or remove inverter.


Paul Shovestul
BMW CCA 69606





I tested for spark tonight and there is none. Swapping my 402 ECU with a spare 403 ECU I have had no effect.

I also tested post 30 on the fuel pump relay socket. The reason that there is only 3 volts coming out of the fuel pump relay is because there is only 3 volts going into it on post 30. This situation is not unique to the fuel pump relay. There was also only 3 volts going to the other 3 relays.

I have no voltage going to the throttle position sensor. There was 12 volts to the + post under the hood while jumping the car.

I am not sure what is causing this. It may be something defective with my wiring or something else.

I do have a voltage regulator and an inverter bolted to the posts of my battery. Perhaps one of them is malfunctionaing and causing low voltage. I do not know where the voltage to the relays comes from. I don't know if it comes direct from the battery or through some other circuitry.

Any ideas?

[bissellh]

3 volts at post 30 with 12 volts at battery....... Now you're on to something. If engine cranks ok then inverter isn't a problem. Post 30 is directly connected to battery according to page 0670.2.00 in the ETM. The fusable link doesn't come into play and I'm sure a '92 is too old for EWS or DWA. Inspect/check connections at battery and starter. You'll have to follow the wire from post 30 back toward the battery to find the problem. ETM shows (2) splices in wire between post 30 and battery.

You could run a FUSED jumper from + battery terminal to post 30, reinstall FP relay and see if car starts.

Edit: On second thought....if inverter is spliced into wire that feeds post 30 and that connection has failed, then it could be the problem. Check connections and/or remove inverter.


Paul Shovestul
BMW CCA 69606

For clarification, I have 12 volts at the positive jumper terminal under the hood. You see, my battery is now dead from trying to start the car and I am jumping the car via the jumper terminal under the hood with my truck battery. I did not check the votage at the battery under the back seat while I am jumping the car. I will do that tonight.

When you say a fused jumper, you mean a wire with a fuse on it? What rating fuse would you suggest I use to jump post 30 of my fuel pump?

[bissellh]

Did you ever find / check the fusible link?

Just curious,

Dave

I searched the threads briefly and did not come up with any information about the fusible link? Besides, I thought it was some lingo you guys were using to describe the damaged crank pulse sensor wire that I replaced a few weeks back, described at the begiining of this thread. What is it and where is it and how do I test it?

[Dave M]

Don't worry about the fusible link. Here is a fused 'jumper wire' with a switch. the fuse just sits in a $1 plastic bit you can get at an auto parts or electronis store. You don't necessarily need the switch, but it is handy for other things.

http://img.photobucket.com/albums/v11/dave_macisaac/Bimmer/Fuel%20Pump/DSC00505.jpg

Dave

[bissellh]

Don't worry about the fusible link. Here is a fused 'jumper wire' with a switch. the fuse just sits in a $1 plastic bit you can get at an auto parts or electronis store. You don't necessarily need the switch, but it is handy for other things.

http://img.photobucket.com/albums/v11/dave_macisaac/Bimmer/Fuel%20Pump/DSC00505.jpg

Dave

I went out to my car and jumped it with my truck again. This time I checked for 12 volts at the battery under the back seat and it was there. Apparently the inverter and voltage regulator were not adversely affecting the voltage across the battery. Just to be sure, I disconnected both the regulator and inverter and checked again. Again, 12 volts. However, there was still only 3 volts at the relay 30 post. I checked post 30 of all three relays and got only 3 volts. I noticed a black plastic terminal in line with the relays. It has two red wires that connect at this black plastic terminal block. I tightened the nuts that hold each red wire to the terminal block. I had to turn one nut about ten revolutions. That resolved my problem. After all of this, it appears that a loose wire connection was causing the problem.

My engine was replaced not too long ago. The mechanic must have forgotten to tighten those wires.

Thanks for checking the wiring diagram to let me know that there is almost a direct connection between the battery and the relays. Knowing that really narrowed down my search and enabled me to find this issue and resolve it.

[Dave M]

I went out to my car and jumped it with my truck again. This time I checked for 12 volts at the battery under the back seat and it was there. Apparently the inverter and voltage regulator were not adversely affecting the voltage across the battery. Just to be sure, I disconnected both the regulator and inverter and checked again. Again, 12 volts. However, there was still only 3 volts at the relay 30 post. I checked post 30 of all three relays and got only 3 volts. I noticed a black plastic terminal in line with the relays. It has two red wires that connect at this black plastic terminal block. I tightened the nuts that hold each red wire to the terminal block. I had to turn one nut about ten revolutions. That resolved my problem. After all of this, it appears that a loose wire connection was causing the problem.

My engine was replaced not too long ago. The mechanic must have forgotten to tighten those wires.

Thanks for checking the wiring diagram to let me know that there is almost a direct connection between the battery and the relays. Knowing that really narrowed down my search and enabled me to find this issue and resolve it.

Finally,

Congratulations!!!!!!!

Dave