Stumble and stall

[johngreenedc]

1992 (9-91 build) 525i, m50, 165000m, manual trans, With in the last few weeks my wife reported a problem (one time) withthe car stalling in the middle of driving around 50 mph, like she was running out of gas. The car was low on gas so I didn't pay much attention until it stumbled and nearly stalled on my way to the office. I knew I was nearly out of gas (the range was showing ---- [under 9 miles]) but I should have had a 3 mile or so margin to the gas station. Intead I stalled a half mile or so away. Coasted to the curb and was able to start the car, get to the station and gas up. Got to the office with a couple of stumbles when it felt like the car ws running outof gas but no stalls. After work car starts fine, then 10 minutes of so later stalls and would not start again. Engine cranks strongly but does not sound like it is gettng any gas. Finally 5-10 minutes later the engines fires up and I get home.

After reading the forums I changed the fuel filter as a first step. After the car started with no problems and run fine to the office (about 9 miles). After work started fine but I turned it off to go back inside. Second tme the car started and rn for 30 seconds then stalled. I had to wait for anouther 5-10 minutes before it started and kept running. Made it home with no stalls but several stumbles (at various speeds from 35-55 mph).

Any ideas about what is wrong? What is my next step?

When I changed the fuel filter I also had to install a new fuel hose and when running to check for leaks at the fuel pump (none) i listened carefull and heard no hissing or whine from the pump. In fact very difficult to hear anything from the pump. Is that good ? or bad?

thanks for any help.

John

[Dave M]

Welcome John,

As you likely know, things like this can be difficult to pin down quickly. It certainly sounds fuel related, so I'll throw out a few things you might want to start with.

1)Test your fuel pressure. Its an excuse to buy a cheap, useful tool ;) If its normal, leave the gauge connected for a while in the trunk (ensure everything is nice and tight and check it often). If it has a stumbling fit or its hard to start, you’re ready to hop out and get a reading. I did this a while back to diagnose something similar and it worked.
2) Try a new fuel pump relay. Cheap and easy to do, a pic of its location in the 'black box' on the pass. side under the hood is below.
3) Check the connectors (wiring) at the fuel pump. See this old thread (http://www.bimmer.info/forum/showthread.php?t=30111)

4) New fuel pressure regulator ??


http://img.photobucket.com/albums/v11/dave_macisaac/Bimmer/Fuel%20Pump/DSC00502.jpg

Dave M

[johngreenedc]

Thanks for the reply Dave M. I went to the second suggestion and replaced the fuel pump relay. Drove the car yesterday with no problems. Several 8-10 mile trips, went to redline, started off in second, etc. Stopped car for intervals of 1-5 minutes, 20-30 minutes, and 1-2 hours. Car starts immediately with no hesitation, and the idle is rock solid at 700 rpm after it warms up. Hopefully, I can stop worrying.

Also, the new fuel pump relay has five pins instead of four because the new ones are multiple use. The fifth pin goes into a "no contact" slot in the middle fuel pump relay postion (thanks for the photo).

Thanks again.
John