Car won't start; suspect fuel problem

[Al Gray]

Help! My 1992 525i had an overheating problem. Thermostat changed solved it. Today it would not start. Engine turns over and cranks like a mother but it won't even sputter. I suspect a fuel pump problem or possilby a relay or a fuse. The car was running fine yesterday. It now has 218,000 miles and I know I have never replaced the fuel pump. How should I diagnose this problem and if it is the pump is it a big deal to change? Any help would be appreciated.

Al Gray (Age 62 and still kickin' ass)

[632 Regal]

Check voltage at the pump first. If no voltage will need to track voltage from the fuse box back.

If good then you should hook a gauge to the end of the fuel rail and check pressure.

The pump is in the tank accessible through a panel on the trunk floor. Sounds easy enough to me.

[Ross]

Check for spark too. A squirt of carb cleaner in the intake will tell you if it's a fueling problem, unless the plugs are wet.
Most common sudden death in the fuel system would be the relay, in the ignition probably the crank position sensor.

[Al Gray]

Check voltage at the pump first. If no voltage will need to track voltage from the fuse box back.

If good then you should hook a gauge to the end of the fuel rail and check pressure.

The pump is in the tank accessible through a panel on the trunk floor. Sounds easy enough to me.

I have a Craftsman Digital Multi-meter. I assume I would need to place the leads from the multi-meter on both sides where the wiring connects to the pump. I also assume that I would need the ignition key in the on position. If no voltage they I need to see if I fuse is blown or the relay is bad.

Regarding checking pressure to the end of the fuel rail; what type of gauge do you recommend and which end of the fuel rail?

Al Gray

[Al Gray]

Check for spark too. A squirt of carb cleaner in the intake will tell you if it's a fueling problem, unless the plugs are wet.
Most common sudden death in the fuel system would be the relay, in the ignition probably the crank position sensor.

Spraying carb cleaner in the intake (specifically do you mean where the intake box is that holds the air filter); would that be like spraying ether in the intake, starting fluid. For the ignition; where is the crank sensor located and what should I look for to indicate if it is bad.

Al Gray

[Ross]

Look for a vacuum port or hose connection that is easy to disconnect, spray in there. You're just trying to give the engine something to burn should it have spark.
The crank sensor is mounted on the front of the engine at the perimeter of a toothed wheel attatched to the crank. According to Bentley the resistance should be 1280 ohms +- 10% and air gap should be 1.0mm+-.3 Sometimes a sharp rap on a dead one will bring it back, temporarily.

[Al Gray]

Look for a vacuum port or hose connection that is easy to disconnect, spray in there. You're just trying to give the engine something to burn should it have spark.
The crank sensor is mounted on the front of the engine at the perimeter of a toothed wheel attatched to the crank. According to Bentley the resistance should be 1280 ohms +- 10% and air gap should be 1.0mm+-.3 Sometimes a sharp rap on a dead one will bring it back, temporarily.

I sprayed some starter fluid (ether) into the intake (large hose conection after the air filter box that connects to the intake). The card made an attempt to start and ran very briefly. Therefore it is not a spark/ignition probelm. I located the computer box on the passengers side firewall and located the fuel pump relay which is a 4 prong one located as the middle relay of 3 relays and swapped it with another relay which is 4 prong. I attempted to start the car. The car turns over but does not start or catch. I have read that usually the fuel pump relay is the culprit when the car instantly gets no fuel. There was no indication of fuel pump failure (sputtering, hesitating, etc.). This litterally happened over night where the car was running perfectly to the next day where it would not start (car turning over but not catching or trying to start) at all. Seems to me that maybe I should still replace the fuel pump relay and try it ($17 ) before I spend $200 plus on a new fuel pump. By the way the car has 218,000 miles on it and to my knowledge the fuel pump has never been replaced. Any thoughts would be appreciated.

Al Gray

[Rus]

Jump the relay with a piece of heavy wire. To do this, look at the relay. It'll have a diagram on the side. Using the diagram determine which contacts are closed when the relay is energized. Next install a jumper into the contacts in the relay socket (ie, instead of the relay). This should energize the pump and you should hear it run inside the tank. Run over to the driver's seat and crank the car. If it starts, the issue is definitely with the relay. If the car still fails to start, the issue is either upstream of the relay or the pump is dead. Good luck :)

[Al Gray]

Jump the relay with a piece of heavy wire. To do this, look at the relay. It'll have a diagram on the side. Using the diagram determine which contacts are closed when the relay is energized. Next install a jumper into the contacts in the relay socket (ie, instead of the relay). This should energize the pump and you should hear it run inside the tank. Run over to the driver's seat and crank the car. If it starts, the issue is definitely with the relay. If the car still fails to start, the issue is either upstream of the relay or the pump is dead. Good luck :)

What would be upstream of the relay other than the fuse #23. I checked that and it is fine. I will try to jumpstart the relay but my suspicion at this point is the fuel pump since it is original as far as I know. Your thoughts?

Al Gray

[Jeff N.]

Jump the relay. I'll wager that's your problem. Relays are known to fail.

[Ross]

Jumping the relay and then checking for power and good ground to the pump will narrow it down.
Was the pump noisy previously?

[zuzuk212]

What would be upstream of the relay other than the fuse #23. I checked that and it is fine. I will try to jumpstart the relay but my suspicion at this point is the fuel pump since it is original as far as I know. Your thoughts?
Al Gray

Jump where pins 30 and 87 of relay would connect. I'm going through the same thing ... at least it died in the garage with 240k miles on it. When I jumped it, had voltage but did not hear a thing from the pump when I tested it.
Getting a pump from BMA for $186 ... quoted at first 199 =P Patrick BMW quoted me $161!! Which is fantastic and unbelievable ... till I found out that they didn't have it in stock and would take 3 days =( so much for that deal.

I'm not looking forward to removing the rusted nuts.
Ken

[ScottyWM]

Al, not to sound like a wise-ass, but at our age we tend to forget stuff. Are you sure you have enough gas in it? Is it parked level? My daughter called me one day all frantic that her car wouldn't start and she was late for work. Turned out she had parked nose-down on an incline with just a couple gallons of gas in it. The fuel pump was suckin' air. I stuck a couple more gallons of fuel in it and it fired right up.

[Al Gray]

Al, not to sound like a wise-ass, but at our age we tend to forget stuff. Are you sure you have enough gas in it? Is it parked level? My daughter called me one day all frantic that her car wouldn't start and she was late for work. Turned out she had parked nose-down on an incline with just a couple gallons of gas in it. The fuel pump was suckin' air. I stuck a couple more gallons of fuel in it and it fired right up.

That was one of the first things I did because the gauges are funky when you first start the car. My son has been known to run it right down to E. Thanks for the thought.

[whiskychaser]

Al, not to sound like a wise-ass, but at our age we tend to forget stuff. Are you sure you have enough gas in it? Is it parked level? My daughter called me one day all frantic that her car wouldn't start and she was late for work. Turned out she had parked nose-down on an incline with just a couple gallons of gas in it. The fuel pump was suckin' air. I stuck a couple more gallons of fuel in it and it fired right up.
I think this should be stickied under 'wont start' problems:D Parked one night with the front end on a speed bump. Fuel gauge showed 1/4 and low fuel light wasnt on. I guessed what the problem was and pushed it off the bump. Fired up after a couple of turns.

[Al Gray]

Jump the relay. I'll wager that's your problem. Relays are known to fail.

I just bought a fuel pump relay and tried to start the car. The results were the same. You can't hear the pump running and the car won't start. I guess that leaves the fuel pump. Any other thoughts?

Al Gray

[Al Gray]

I think this should be stickied under 'wont start' problems:D Parked one night with the front end on a speed bump. Fuel gauge showed 1/4 and low fuel light wasnt on. I guessed what the problem was and pushed it off the bump. Fired up after a couple of turns.

Just to be on the safe side I will add a couple more gallons of gas. I did that with no results. Yes, the car is parked in my driveway with the front end higher than the back end. Seems to me that all the gas should be in the tank. But a few gallons of gas is cheaper than a new fuel pump. I questioned my son today about the car just before we couldn't start it (which happened in the driveway overnight) and he said the car did stop on him but he was able to restart it. Was that the initial death toll of the fuel pump? Maybe so.

Al Gray

[Ross]

Have you checked for power at the pump and ground? A poor ground has left me sitting the side of the road once.

[Al Gray]

Have you checked for power at the pump and ground? A poor ground has left me sitting the side of the road once.

Not being an electrical whiz be more specific. I have a multi-meter. Exactly how would I check the pump and ground.

[zuzuk212]

Yep! It was the fuel pump! Connected the old one after pulling it out ... it ran ... no way was I putting it back in though. I had a slight hunting idle and occasional hesitation before ... not any more with the new pump. It lives again!:D

I can recomend a product from CRC, freeze off ... worked great for the rusted nuts ... smells great too ... a lot better than gas fumes:p

Ken

[Mordan]

buying a new pump is not a bad investment anyways if you plan keeping the car

[Al Gray]

buying a new pump is not a bad investment anyways if you plan keeping the car

I just installed a brand new Bosch electric fuel pump from BMA. I know the old pump was the original with 220,000 miles because it still had those rotten factory hose clamps which are a PIA to get off. We try to start the car and I cannot hear any noise or whining from the new pump while we are cranking the engine. I had the same problem with the old pump. I replaced the pump relay. The fuse is good. The electrical connection to the pump looked good. I am frustrated. What else could becausing a brand new pump not to work. I would love some ideas and things to check.

Al Gray

[Al Gray]

I just installed a brand new Bosch electric fuel pump from BMA. I know the old pump was the original with 220,000 miles because it still had those rotten factory hose clamps which are a PIA to get off. We try to start the car and I cannot hear any noise or whining from the new pump while we are cranking the engine. I had the same problem with the old pump. I replaced the pump relay. The fuse is good. The electrical connection to the pump looked good. I am frustrated. What else could becausing a brand new pump not to work. I would love some ideas and things to check.

Al Gray



When I replaced the pump the new Bosch pump had spade type clips and an adapter. The old wires had a coneector with a whole in it that was held on with a nut. You could tell one wire lead was slightly lareger. The new connecors I couldn't really tell which was which. I then read the Bosch installation instructions and apparently the polarity does make a difference. At this point I guess I need to take the pump out again and switch the position of the two connectors. Any thoughts?

[Ross]

Have you confirmed power getting to the pump? And ground? All I notice is your mention that the connections looked good.
Polarity will make a difference.

[whiskychaser]

Have you confirmed power getting to the pump? And ground? All I notice is your mention that the connections looked good.
Polarity will make a difference.
x1
Can you confirm you have a good ground and 12V supply at the pump? No insult intended - its easy to confuse readings on a DMM. With an analog you just watch if the needle swings right or pegs hard left:D

[Al Gray]

x1
Can you confirm you have a good ground and 12V supply at the pump? No insult intended - its easy to confuse readings on a DMM. With an analog you just watch if the needle swings right or pegs hard left:D

Frustrated and pissed after installing a new fuel pump to no avail I took the car to my trusted independent mechanic. The crank sensor was the problem. $108 plus labor got the car started and it is now running. I don't feel bad about replacing the fuel pump because it was original and would evnetually fail. There is a couple remaining problems however. Seems we have a power steering fluid leak. The resevoir is located up on driver's side fender well. Right below it is a hose from the radiator which has been weakened because of the power steering fluid dripping on it. My mechanic should solve that problem hopefully. I try to do as many repairs as I can but sometimes I just get stymied.

To make matters worse I found out I had a fractured navicular bone in my left foot. I don't even know how that happened because I can't recall an event that would cause that trauma. I needed to have surgery and I now have a screw in my left foot that will stay their permanently (they even countersunk the screw so that the head is just below the bone surface). I will have a Frankenstein-like boot with a lot of velcro instead of a cast and crutches of course for the next 6 weeks so my mobility is limited.

Thanks again to all that tried to help me with this project. You guys are the best!

Best regards,

Al Gray

[Ross]

I sprayed some starter fluid (ether) into the intake (large hose conection after the air filter box that connects to the intake). The card made an attempt to start and ran very briefly. Therefore it is not a spark/ignition probelm. I located the computer box on the passengers side firewall and located the fuel pump relay which is a 4 prong one located as the middle relay of 3 relays and swapped it with another relay which is 4 prong. I attempted to start the car. The car turns over but does not start or catch. I have read that usually the fuel pump relay is the culprit when the car instantly gets no fuel. There was no indication of fuel pump failure (sputtering, hesitating, etc.). This litterally happened over night where the car was running perfectly to the next day where it would not start (car turning over but not catching or trying to start) at all. Seems to me that maybe I should still replace the fuel pump relay and try it ($17 ) before I spend $200 plus on a new fuel pump. By the way the car has 218,000 miles on it and to my knowledge the fuel pump has never been replaced. Any thoughts would be appreciated.

Al Gray

"The card made an attempt to start and ran very briefly. "
The red herring. Damn CPS
Glad it's sorted. Had you kicked the car?