fuel pump, engine won't start 7/1994, 525it, M50TU

[werminghausen]

The engine doesn't start.
Story My wife was driving and all seemed normal. Then she was parking and then after 2 hours the car did start but the engine was starving and died..didn't start again.
The starter is strong but the engine won't start. I pulled the car home and it is sitting in my driveway.
History: I have replaced the starter one week ago. I took off the air intake and I had the battery out.

Today I was starting with some analysis:
1) I was measuring the fuel pressure before the fuel rail. I installed a pressure gauge and turned key to position 2. result: 0.2PSI, no pressure. If there is no fuel the engine can't start.

2) I was opening the access panel to the fuel pump (wow was it rusty under neath!) and pulled the 5 prong connector.
I measured if there is 12V at Socket/Pin 4 (-, ground) and 5 (for +) with key in position 2: NO VOLTAGE!
I checked Fuse 23 and it was GOOD.
I was trying to find the Fuelpump Relay in order to jumper the Relay to see if I can get voltage at the fuel pump socket at least.
I pulled an orange relay (not sure at all if this was the fuelpump relay) next to a white relay... and I jumped Socket/Pin 30 and 87 (of the icecube relay) but with no result. I still got no voltage at the fuel pump connector.
My guess is that it was the wrong relay?
How can I identify the fuel pump relay?

3) Then I was applying power directly from the battery to the pump (Ground to Pin 4 and Battery + to Pin 5) and NOTHING! If these are the correct pins to run the pump - then my pump is dead!

Questions:
a) Why do I have no voltage at the fuel pump socket with key in position 2 and relays in original position.
b)Is there a timing issue that the pump does just produce a small pressure, the 0.2PSI and the shuts off unless the engine is running?
c) It is not quite logical to me that 2 electrical problems occur at exactly the same time:the pump is dying and at the same time another electrical component as part of the power delivery to the pump. What do you think?
d) could there be any connection with the previous air intake R/R and starter exchange or battery exchange? did I damage some wires?
But..why did the car run without any trouble for a week?


Can you guys help me out to solve the problem?
Martin

[Dave M]

I was trying to find the Fuelpump Relay in order to jumper the Relay to see if I can get voltage at the fuel pump socket at least.
I pulled an orange relay (not sure at all if this was the fuelpump relay) next to a white relay... and I jumped Socket/Pin 30 and 87 (of the icecube relay) but with no result. I still got no voltage at the fuel pump connector.

My guess is that it was the wrong relay?
How can I identify the fuel pump relay?

3) Then I was applying power directly from the battery to the pump (Ground to Pin 4 and Battery + to Pin 5) and NOTHING! If these are the correct pins to run the pump - then my pump is dead!

Questions:
a) Why do I have no voltage at the fuel pump socket with key in position 2 and relays in original position.
b)Is there a timing issue that the pump does just produce a small pressure, the 0.2PSI and the shuts off unless the engine is running?
c) It is not quite logical to me that 2 electrical problems occur at exactly the same time:the pump is dying and at the same time another electrical component as part of the power delivery to the pump. What do you think?
d) could there be any connection with the previous air intake R/R and starter exchange or battery exchange? did I damage some wires?
But..why did the car run without any trouble for a week?


Can you guys help me out to solve the problem?
Martin

I have a good old post about this problem, but the search function doesn't work for me and Google isn't helping either. So back to square one:

First, the relay is easy to find. See below. I assume pins 30 and 87 are the ones I have jumped with my homejob switch.
http://img.photobucket.com/albums/v11/dave_macisaac/Bimmer/Fuel%20Pump/DSC00502.jpg

Regarding applying power directly to the pump, by "fuel pump socket" are you referring to the electrical connector in the trunk as shown below??

http://img.photobucket.com/albums/v11/dave_macisaac/Bimmer/Fuel%20Pump/DSC00516.jpg

If you've properly identified the power source wires (double check Bentley for details-I don't have mine handy to verify your pins) and directly applied 12V, then you pump is pooched.

Questions:

a) Disregarding applying 12V direct to pump, this is a classic bad fuse or relay. Regarless of your pumps health, you should still have 12V at the connecter. Sounds like you've checked the fuse, so lets rule out the relay (which the above photo should help do).

b) Not sure I entirely understand the question, but IF properly jumped (again, see first photo), the pump will run all day or untill the battery dies (ask me how I know). When jumped, its more than loud enough to hear with the engine off.

c) I think you're dead on, it does sound fishy, which is why I would verify everything you've done so far. Then, if you're lucky, you only replace one, preferrably the cheap relay!!

d) Highly doubtfull.

Good luck and keep us posted.

Dave M

[werminghausen]

I have a good old post about this problem, but the search function doesn't work for me and Google isn't helping either. So back to square one:

First, the relay is easy to find. See below. I assume pins 30 and 87 are the ones I have jumped with my homejob switch.
http://img.photobucket.com/albums/v11/dave_macisaac/Bimmer/Fuel%20Pump/DSC00502.jpg

Regarding applying power directly to the pump, by "fuel pump socket" are you referring to the electrical connector in the trunk as shown below??

http://img.photobucket.com/albums/v11/dave_macisaac/Bimmer/Fuel%20Pump/DSC00516.jpg

If you've properly identified the power source wires (double check Bentley for details-I don't have mine handy to verify your pins) and directly applied 12V, then you pump is pooched.

Questions:

a) Disregarding applying 12V direct to pump, this is a classic bad fuse or relay. Regarless of your pumps health, you should still have 12V at the connecter. Sounds like you've checked the fuse, so lets rule out the relay (which the above photo should help do).

b) Not sure I entirely understand the question, but IF properly jumped (again, see first photo), the pump will run all day or untill the battery dies (ask me how I know). When jumped, its more than loud enough to hear with the engine off.

c) I think you're dead on, it does sound fishy, which is why I would verify everything you've done so far. Then, if you're lucky, you only replace one, preferrably the cheap relay!!

d) Highly doubtfull.

Good luck and keep us posted.

Dave M

Dave, Thanks
I have just 2 relays in my junction box, one is white (oriented toward the engine) and another is orange or the color of your O2 relay (toward the fender). Which one is the fuel relay and which one the DME ?
As mentioned I pulled the orange one and did exactly what you did , jumped 30 and 87 with a 15A fuse in between- and key in position 2: NOTHING
I used the Bentley information about the Socket/Pins at the top of the fuelpump in the the back. If I applied 12 V to the pins I described: PUMP IS DEAD

Again, I ruled out the fuse (I tested it numerous times)
I don't know which one of my 2 relays is the fuel relay. The socket of the orange relay I tested had no continuity to fuse 23 and therefore I believe this is not the fuel relay.
Can someone help me identify the 2 relays I have?
Your top of the fuel tank looks as rusty as mine: I painted it yesterday

[shogun]

check here in the wiring diagrams by production year, all relais and fuses and their locations are shown
http://shark.armchair.mb.ca/~dave/BMW/e34/

[werminghausen]

check here in the wiring diagrams by production year, all relais and fuses and their locations are shown
http://shark.armchair.mb.ca/~dave/BMW/e34/

I guess for my 7/94 I'll go with the 95 diagrams?
I still want to identify: which of the 2 relays is the Fuelpump and which the DME relay? Any idea?

[werminghausen]

I have again measured voltage at the socket to the fuelpump (which is off right now). There is NO voltage at any time when key is turned into position 2. I measured between socket 4 (ground) and 5 (+).
The I measured resistance between Pin 4 and 5 (of the pump side) and there were 5KOhm. What does this tell?
I also pulled both relays. The orange one is definetely the pump relay (4 prong) and the white one is the DME relay (5 prong). I have ordered both relays new in order to eliminate this potential problem.
Martin

[alex 1993 525i auto]

Another way to check without removing the relay is to check voltage at the fuel pump connector while you're cranking the engine (need a helper obviously). If no voltage when cranking (with all relays and fuses installed), then the problem is between the key and the fuel pump.
If voltage on the connector, then it is the pump or the fuel level sender. In my case it was the fuel level sender which was worn, not the pump, neither the relay. When the fuel level sender is worn, the pump doesn't receive the power and doesn't run.

(the fuel level sender is the place where the connector plugs in and tells how much fuel remains in the fuel tank, but the pump is under the sender, connected to it, so if the sender doesn't work the pump can't work)
Unless I'm wrong...

[werminghausen]

Another way to check without removing the relay is to check voltage at the fuel pump connector while you're cranking the engine (need a helper obviously). If no voltage when cranking (with all relays and fuses installed), then the problem is between the key and the fuel pump.
If voltage on the connector, then it is the pump or the fuel level sender. In my case it was the fuel level sender which was worn, not the pump, neither the relay. When the fuel level sender is worn, the pump doesn't receive the power and doesn't run.

(the fuel level sender is the place where the connector plugs in and tells how much fuel remains in the fuel tank, but the pump is under the sender, connected to it, so if the sender doesn't work the pump can't work)
Unless I'm wrong...

Thanks
Do you have another electrical
diagram?
According the electrical diagram Shogun sent for the '95 there should be power at the pump all the times with key in pos.2 when socket 30 and 87 are bridged at the fuel relay (with fuel relay removed) but this is not the case.... (if I measure at socket 4 and 5 at the pump)

[genphreak]

NonNonononononon

No power at relay or pump unless the engine is cranking. Standard safety feature on most modern EFI cars, to stop fuel pump in the event the engine stops cranking- reducing the risk of fire after accidents, etc.

Only test when cranking. If still no power, upstream one must check the Crank Position Sensor as this tells the ECU when the engine is cranking.

[werminghausen]

NonNonononononon

No power at relay or pump unless the engine is cranking. Standard safety feature on most modern EFI cars, to stop fuel pump in the event the engine stops cranking- reducing the risk of fire after accidents, etc.

Only test when cranking. If still no power, upstream one must check the Crank Position Sensor as this tells the ECU when the engine is cranking.

Thanks for the info. Someone mentioned before that the pump is priming for a short period of time when key is in psoition 2 and then pump (DME) turns it off if engine is not cranking.
I didn't get any signal for 'priming' at the pump connector though.
In theory I can jump the pump relay by connecting Pin 30(always hot) and Pin 87 at the socket? Then there must be power at the pump connector?

Test o f the pump itself without removing it: If I apply power directly at the pump connector, pin 4 (minus) and Pin 5 (plus) then the pump should run- correct?
If not the pump is dead. Am I correct? Martin

[alex 1993 525i auto]

I suggest again an easy test to try, i.e. to check if you read power on your pump connector at pins 4 and 5 (I guess as you say, I don't remember), when someone crank the engine, then you'll see if everything's fine between the connector and the computer and above.

If you see voltage when cranking, and as you say the pump spins when plugged directly to the battery, it is most probably the fuel level sender (fls).

You can test that too with your multimeter and look at the resistance between 2 of contacts on the connector of the fls, you can find the typical resistance expected online I guess, or in the Bentley. Those two test can be done without removing the fuel pump.

Anyway if the pump or fls are worned out, you'll have to remove it, but it's not a big deal. I think if you don't crank the engine to test voltage even with the jumper, you cannot know that the pump is dead neither the fls. I think you're juper is to prevent the engine from starting (prevent the spark plug to do their job), for safety.

Hope this help,
Alex

[werminghausen]

Thanks for the tip cranking the engine.
So far I have not tested if there is power on the pump socket when cranking. So there is a chance....but in the electrical diagram Shogun gave me...in the 95' diagram ...it shows that 30 is always hot when key in pos.2.
Then in theory if I jump 30 and 87 (like Dave said and shower in pics..with a switch and 16A fuse) then there must be power at the pump.
But I'll definitely test the same under cranking condition. I think that cranking gives the DME relay input (signal from crankshaft) and then gives signal to the Pump relay closing the circuit.

For your information. I applied power to the pump directly (4 minus and 5 plus pole) and it is definetely NOT moving. I ordered a new pump from Treperformance and I ordered both relays in order to make sure that there is no culprit.

I'll do more electrical testing tonight and report back

Do I need to empty the fuel tank for changing the pump?



I suggest again an easy test to try, i.e. to check if you read power on your pump connector at pins 4 and 5 (I guess as you say, I don't remember), when someone crank the engine, then you'll see if everything's fine between the connector and the computer and above.

If you see voltage when cranking, and as you say the pump spins when plugged directly to the battery, it is most probably the fuel level sender (fls).

You can test that too with your multimeter and look at the resistance between 2 of contacts on the connector of the fls, you can find the typical resistance expected online I guess, or in the Bentley. Those two test can be done without removing the fuel pump.

Anyway if the pump or fls are worned out, you'll have to remove it, but it's not a big deal. I think if you don't crank the engine to test voltage even with the jumper, you cannot know that the pump is dead neither the fls. I think you're juper is to prevent the engine from starting (prevent the spark plug to do their job), for safety.

Hope this help,
Alex

[Tiger]

You can measure the voltage at the relay point... either you get it or you don't get it. The circuit that goes to the fuel pump... check both side of the relay ports for any sign of voltage... you use chassis ground as ground and stick red probe into either plugs.

[werminghausen]

You can measure the voltage at the relay point... either you get it or you don't get it. The circuit that goes to the fuel pump... check both side of the relay ports for any sign of voltage... you use chassis ground as ground and stick red probe into either plugs.

I have measured again today with Shogun's electrical diagrams.

1) I find 12V+ at Pin /Socket 30 of Fuelpump Relay - GOOD.
2) NO continuity from Socket/Pin 87 of the Pump relay to Fuse #23- This is frustrating!
3) Continuity from Fuse 23 to Socket of pump in the back.
4) Pump is not moving if I apply power directly

Result: I have 2 problems
1) Pump is dead
2) Wire X8007 (1.5 GN/VI Green/Violett) is broken or disconnected - this is frustrating and I can't understand how these 2 problems can show up at one point in time?

Does anyone have a clue how the 2 problems are related?
Well, I have changed the starter 10 days ago and I might have damaged the wire X8007?
I see a connector in the diagram...it is connector X20 at contact 13? Can someone tell where I find this connector?
Maybe I have the chance to find the problem at connector X20 or at least I just need to replace one part of the cable..




I have ordered a new pump from Treperformance- seems to be straight forward to change?
Treperfromance is relatively cheap and I heard good things- has someone done this job?

Wire X 8007 replacement: Can someone tell me how to replace this wire from 87 to Fuse 23?
Can I tap into the wire right at the relay and the fuse? what do you think? Has anyone done such job before?

[werminghausen]

No continuity between Pump relay 87 and fuse 23
Wire X 8007 replacement: Can someone tell me how to replace this wire from 87 to Fuse 23?
Can I tap into the wire right at the relay and the fuse? what do you think? Has anyone done such job before?[/QUOTE]

In the digram I saw that the Green/Violet wire from Pin 87 of the relay to fuse 23 has a Connector X20 in between relay and fuse. I found the Connector: It is the big round 25 Pin connector next to fuse box and watervalves. It is position 13 there. The cable from Pin 13 to Fuse is good- has continuity. But the cable from Relay pin 87 to connector X20 is dead- no continuity.
So I narrowed down the problem: If I jump the part from relay to X20 and apply battery + at Pin 87 at relay I have power at the pump!
So the cable from Pin 87 to X20 connector is broken somewhere
Does anyone know what the Dot in the wire line (wire line from Relay to Fuse) in the wire diagram (diagram 1210.13-02)means. Next to this dot there is X8007. I thought in the beginning that X8007 is the cable itself but I am sure it means something else. In other diagrams the dot means that another cable is joining. Maybe this is a hint to find the culprit... Please help

[tim eh?]

Check page 1210.11-04, it splits to the e-box fan. Usually you can cross reference those #s in sections 7000 but not all are listed.

[werminghausen]

case is solved. It is my fault.
After ripping out all cables between relay box and X20 connector. I found that the relay that I thought is the pump relay wasn't the pump relay but maybe the Oxygen sensor relay- has also 4 pins while the DME relay has 5. There was a third relay hiding in the back (blue color) and I didn't see it before.....Oh my god.
Electrical is so not my thing.

So I was mistaken and the pump relay (the blue one in the back) seems to be good and I have power at the pump socket as soon as the crankshaft is cranking ...well engine doesn't start. With key in Position 2 there is NO priming at all- no power at the socket.

I am waiting for the new pump from Treperformance and then with the new pump the engine should run
Martin

[genphreak]

Sorry for the late reply. To test the pump please jumper the relay and confirm the pump is making noise by listening near the tank.

If so, it's your ecu (or more likely, inputs to it).

Beware immobilization systems, I've just found my problem is the dealer fitted alarm (hasn't ever worked AFAIK), it is disabling the spark.

[werminghausen]

The question: when is there power at the pump? There are actually 3 different opinions and I wanted to make sure my car is doing the right thing.

1) Some say there is ALWAYS power at the pump when key is in position 2
2) Others say that the pump is 'priming' or running for a short time in key position 2, then turns off if engine is not starting. Then of course the pump is running with engine cranking.
3) In my case the pump has power only when I am cranking the engine.

So what are the experts saying?
Martin

[werminghausen]

I did install the Treperformance pump.
It didn't quite fit. I had to cut out the bottom of the plastic housing where the pump itself is embedded. The stainer is not quite as low as for the original pump. Maybe the intake is 1/2" higher. Do you think this is a problem? I mean do I need to be careful that I am running out of fuel much earlier?

The car started and acted normal.

Thanks for all your help.
Martin

[citti2004]

I am having a very similar issue which I posted about. The difference on mine, I think, is that I don't seem to get any volts at the pump whith the key on or off. So i decided to bring it to a mechanic to check and fix it..


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