1992 735i stalling intermittently - solved

[choirsilva]

My daughter's 1992 735i has been stalling intermittently. It usually starts right back up but, sometimes has to sit for up to 5 minutes before restarting. Other than the stalling, it runs great. When it stops running, it is accompanied by the fuel gauge swinging from its correct reading to Empty, sometimes jumping back and forth between empty and the accurate gauge reading. There are no stored codes using the stomp test.

Thanks in advance for any pointers as to what to look at.

Christopher

[shogun]

Check the fusible link A, maybe it has a crack and sometimes works and sometimes not. It is located close to the battery and hidden in plastic wrap, pics are on my website, here the link https://www.bimmerforums.com/forum/s...2-fusible-link
Fusible Link A can go intermittent and kill power to the the DME box. You can conveniently check this at your D100 Diagnostic Connector, pin 14. The voltage should be 12V at all times. If it is low when cranking, then Fusible A is your problem.

[TheStigg]

Does it sputter as it stops or does it cut out abruptly? I would start by measuring the reference sensor impedance. Even if it passes, remove the sensor and do a visual inspection of the face. It should have a slight bump in the middle. If it has a groove worn in it, replace it:

cps.jpg

If it sputters as it dies, then look at the fuel pump and fuel pump relay. Odd that it doesn't throw a code. Have you cleared all the codes? Sometimes they will store a code even though the check engine light doesn't come on. Perhaps clearing the code will allow it to store it the next time it dies(?). Other culprits could be the DME relay or the coil or even the rotor. Also check the ground strap on the back of the head to the firewall for corrosion.

A former member on the Roadfly forum had issues with his stalling when the fuel pump intake screen would clog up from debris and the engine would stall. The debris would drop off via gravity when it died and it would start again and run fine until it subsequently caked up.

I had an e28 m20 that would die frequently. I never could pin it down to anything specific. I replaced just about everything fuel/spark related. I opened the case to the DME and spread the pc boards apart and did a visual inspection with a magnifying glass to check all the solder joints, all was intact. I even put a heat gun on the DME boards while it was running to see if I could force it to stall when hitting on a weak component, didn't phase it.

Another thing to check is the ignition switch on the backside of the steering column, opposite the key. Honda uses a similar switch which can precipitate a stall. Honda eventually issued a formal recall for it. I don't know that BMW ever indicated it as a problem.

[TheStigg]

Check the fusible link A, maybe it has a crack and sometimes works and sometimes not. It is located close to the battery and hidden in plastic wrap, pics are on my website, here the link https://www.bimmerforums.com/forum/s...2-fusible-link
Fusible Link A can go intermittent and kill power to the the DME box. You can conveniently check this at your D100 Diagnostic Connector, pin 14. The voltage should be 12V at all times. If it is low when cranking, then Fusible A is your problem.

Good point Erich, I didn't think of that. Highly likely.

[choirsilva]

Does it sputter as it stops or does it cut out abruptly? I would start by measuring the reference sensor impedance. Even if it passes, remove the sensor and do a visual inspection of the face. It should have a slight bump in the middle. If it has a groove worn in it, replace it:

cps.jpg

If it sputters as it dies, then look at the fuel pump and fuel pump relay. Odd that it doesn't throw a code. Have you cleared all the codes? Sometimes they will store a code even though the check engine light doesn't come on. Perhaps clearing the code will allow it to store it the next time it dies(?). Other culprits could be the DME relay or the coil or even the rotor. Also check the ground strap on the back of the head to the firewall for corrosion.

A former member on the Roadfly forum had issues with his stalling when the fuel pump intake screen would clog up from debris and the engine would stall. The debris would drop off via gravity when it died and it would start again and run fine until it subsequently caked up.

I had an e28 m20 that would die frequently. I never could pin it down to anything specific. I replaced just about everything fuel/spark related. I opened the case to the DME and spread the pc boards apart and did a visual inspection with a magnifying glass to check all the solder joints, all was intact. I even put a heat gun on the DME boards while it was running to see if I could force it to stall when hitting on a weak component, didn't phase it.

Another thing to check is the ignition switch on the backside of the steering column, opposite the key. Honda uses a similar switch which can precipitate a stall. Honda eventually issued a formal recall for it. I don't know that BMW ever indicated it as a problem.

I'll start with checking the link A as suggested when my daughter gets home from work in a couple of hours. I don't think it could be a clogged pump strainer as the fuel gauge drops when the car dies so, if it is fuel starvation, the pump and level sending unit are loosing power at the same time. I hope to find that the fuse link has a crack in it as it would be an easy fix. I really appreciate all of the responses as her E32 is very different than the old cars I am used to working on.

Christopher

- - - Updated - - -

It doesn't sputter, it just quits running.

[shogun]

The fuel gauge should not drop when the fuel pump dies, the level sensor is a different thing. Are any other things erratic then like speedo, lights flickering? Then check the fusible links, there are 2 of them. http://www.bimmerboard.com/forums/posts/377728/
The fuel sender and fuel pump also check once more, if the pump is clipped in correct and not floating inside the tank, there are 2 clips which hold the pump in position, when it slips out, it might cause the starvation, here a pic of the clips on a 750 http://bmwe32.masscom.net/sean750/fu...t/Fuelpump.htm

Also a good point by TheStigg to check the crankshaft position sensor, 540 +/- 10% Ohm between pin 1 and 2 http://www.e32-schrauber.de/bmw/s-kw-sensor.htm

[choirsilva]

The fuel gauge should not drop when the fuel pump dies, the level sensor is a different thing. Are any other things erratic then like speedo, lights flickering? Then check the fusible links, there are 2 of them. http://www.bimmerboard.com/forums/posts/377728/
The fuel sender and fuel pump also check once more, if the pump is clipped in correct and not floating inside the tank, there are 2 clips which hold the pump in position, when it slips out, it might cause the starvation, here a pic of the clips on a 750 http://bmwe32.masscom.net/sean750/fu...t/Fuelpump.htm

Also a good point by TheStigg to check the crankshaft position sensor, 540 +/- 10% Ohm between pin 1 and 2 http://www.e32-schrauber.de/bmw/s-kw-sensor.htm

Thanks for the suggestions, I'll start with inspecting the fusable link and then move to a look inside the tank to see if the pump is secured. The lights don't flicker or speedometer falter, just the fuel gauge and cut out of running. Will move to the crank sensor if fusable link and pump mounting seem okay.

[choirsilva]

Checked fusable links A and B with visual inspection and ohm meter, both checked out good, opened the top of the tank and the pump is secure in its clips. Will check the crank sensor when I get home today. After last night's checks, drove the car for an hour and it cut out twice in the first 10 minutes and then ran great for the rest of the hour. Both times it cut out, the engine just suddenly quit running without any sputtering and the fuel gauge went completely to empty.

[SergeBMW]

Checked fusable links A and B with visual inspection and ohm meter, both checked out good, opened the top of the tank and the pump is secure in its clips. Will check the crank sensor when I get home today. After last night's checks, drove the car for an hour and it cut out twice in the first 10 minutes and then ran great for the rest of the hour. Both times it cut out, the engine just suddenly quit running without any sputtering and the fuel gauge went completely to empty.

This sounds like the CPS for sure, easy to reach the connector that sits on the side of the injector rail. There are 2 connectors FWD of the intake, its the one on the firewall side.
Third picture in the link: http://www.bimmerboard.com/forums/posts/411477

The reading between pins should be 540ohms +/- 10%. This is from the Bentley manual. Please correct me if I am wrong.

[choirsilva]

Well, replaced the crank position sensor, checked connections at the starter, checked ground from engine to chassis. Took car for a drive and it still stalled twice and momentarily shut off for split second and then went back to running several times. Unplugging the fuel pump relay it will start to stumble after several seconds and return to good running without effect to the fuel gauge. Unplugging the main (white) relay, the car instantly shuts off but, the fuel gauge remains on and at the proper level. I'm at a loss...... Did stomp test again and it still comes up with 1444 (no codes).

Christopher

[SergeBMW]

Does the entire car turn off including electronics? Or do the gauge lights remain light on?
Cutting the fuel should not change the fuel level indicator at all.

Question. How much fuel is in the car now? And during this entire time of troubleshooting, have you refilled the tank? Could be possible that you have a hole in the pickup line from the pump to the fuel tank cover which may be sucking air when the fuel sloshes around when its half filled or less. This was an issue I had in my 750 with cracked fuel lines inside the fuel sender assembly.

[choirsilva]

The entire car doesn't turn off, just the engine running and fuel gauge, this last drive, I did see the temp gauge quit as well. The lights all remain on. The car currently has 3/4 a tank of premium but, the problem has happened with anywhere from 1/4 to a full tank. I really don't think it is stalling due to fuel starvation as there isn't even the slightest sputter, it just instantly shuts down.

Christopher

Does the entire car turn off including electronics? Or do the gauge lights remain light on?
Cutting the fuel should not change the fuel level indicator at all.

Question. How much fuel is in the car now? And during this entire time of troubleshooting, have you refilled the tank? Could be possible that you have a hole in the pickup line from the pump to the fuel tank cover which may be sucking air when the fuel sloshes around when its half filled or less. This was an issue I had in my 750 with cracked fuel lines inside the fuel sender assembly.

[choirsilva]

Problem turned out to be the ignition switch. $133 at the dealer, 25 minutes to install. Drove for 90 minutes without any problems. Thank you all for the help and advice as I tracked this down.

Christopher Silva, Fairview Oregon

[SergeBMW]

Wow... we all overdiagnosed it hahaha

Glad you got it working!

[TheStigg]

"Wow... we all overdiagnosed it hahaha"

Stiggy got it!

. . .

Another thing to check is the ignition switch on the backside of the steering column, opposite the key. Honda uses a similar switch which can precipitate a stall. Honda eventually issued a formal recall for it. I don't know that BMW ever indicated it as a problem.

[SergeBMW]

"Wow... we all overdiagnosed it hahaha"

Stiggy got it!

Dam! We need a score board Nice work!

[Spd.Saloon]

Hi shogun,
I'm looking to buy a 1994 740i and when I took it for a test drive, it stalled just like choirsilva's one. I don't think the stalling issue is due to the switch though as the idiot light was off when the key was in run position and the car not started. It probably stalled because it ran out of battery and the alternator wasn't charging it. My concern is that, during the ride, the check engine and abs lights started flickering for a few seconds and then went off. You talked about a similar symptom. could you develop about this? what does it mean? can it lead to future problems? the lights flickered only once for a few seconds for a 10 minutes ride.

[Cactuar]

Spd.Saloon did you go test drive the awful blingy 1994 740i for sale at Kenny U-Pull in Brossard?

[Spd.Saloon]

Yes it's that one, I'm looking to get as much info as possible about the issues it got before buying it to get an idea of wath as to be done to make it run great again. And don't worry, if I buy it, first thing I will do is get rid of the chrome fenders and door handles lol.

For the problems I found on the car:
Driver's side seat and mirror commands are inverted, it's probably the seat memory module;
Battery light doesn't light up when the key is in on position and the car isn't running, I hope the bulb is just burnt and that changing it will fix the stalling issue. I really think that the car stalled only because it was out of battery because it restarted right away when boosting it. I know it can be more than just the bulb but from what I've read, I would start by changing the light and see if it works;
As I said in my previous post, the check engine and ABS lights flickered for a few seconds during the test drive, I really dont know what that means, could it only be a bad contact in the instrument cluster circuit?;
It's also missing the radio, as it is related to the anti-theft system, is it a big job to put back an original one in it?;
The last thing is the whole ventilation system not working, the previous owner probably did something to the wirring as the ventilation control pannel hasn't been put back in correctly.

I hope you can help me evaluate how much work has to be done for it to work properly. I would mainly want it to run great and be reliable, the seats and fans not working don't bother me for now.