hey guys. I have a problem. My 740 turbo wagon is quitting on me.
Sometimes i can drive the car prefectly fine for miles and miles. (made a 600 mile trip on friday, a 200 mile trip on saturday. Ran great.) Then on Sunday it would run and then quit after a few miles. I would wait to about 15 minutes and it would start and then go another few miles and die. This happened a few times and then one time it just never stopped. Drove 200 miles back that night. It ran great on tuesday on and off around town with no problem all day. Then today i left for greensboro nc, about 250 miles. Made it there no problem, even stopped to fill up and it was and started perfectly. Then after a few stops there i got on the road and it started quitting again. WHAT to do? Im thinking electrical. how can i get home?

Please help. i got work tommorrow

 

OK. There are a few things it could be. My first guess is your fuel pump relay. It is located where your fuse panel is behind the ash tray. It is in the second row, far left if I recall. Should be white w/ 6 prongs. If your car is 89 or older you have LH2.2 Jetronic. If a 90+ it will be LH2.4 Jetronic. If you have access to a soldering gun, you could probably open it up and re-solder a visible cracked solder joint. More likely, find a nearby j/y and get 2 or 3. Here's what t looks like

Second most likely is the ignition module located on the drivers inner fender near the grill and in front of the strut tower. On n/a cars it is hidden behind the air box but on your turbo, it's pretty much in the open. Looks like this...might try to pull one of these too.

 

I had a '87 740 GLE and my 1st guess was the fuel pump. The relay sounds like a better guess. I actually ran across one of those relays in my bag of tricks about a month ago and I have not had the car for about 4 years. :-) Hope things work out for you.

 

Is the problem on lowish tanks of fuel (like 1/3 tank or less). If so, could be in tank (lift) pump failing.
Also pull the AMM out of the air filter box and check for build up of foam on the mesh.
I don't like relay or module for this, they both tend to fail permanently when they go.

Regards, Andrew.

 

In my professional experience, I've never had a lift pump cause a no run situation in and of itself. Combined w/ a failed/failing main pump then sure. This guy is trying to get home Andrew. Fuel relays are known to fail intermiitently as are, to a lesser degree, ignition modules. As for a build up of foam on the downstream screen of the AMM sufficient to cause the engine to stop running? Suppose it's possible...I mean 500 miles from home I can't see ohming an in-tank pump. Of course, the simple test is to pull the hose from the tank and turn the key on...if gasoline flies everywhere it's a safe bet the lift pump is running. Not recommended from a safety point of view...but rather effective.

 

My experience with main fuel pumps (not in tank ones) is this. When they fail, they can be instantly revived with a strong jet of cool water. The only practical way to achieve this while on the open road is to carry a child's super soaker water pistol (and lots of spare water). You pump it up, aim at the pump (which is under the left seat in a cage), soak it for a good 30 secs or more then presto!! it starts!! Also if the pump has airflow when you travel at more than 60km/h it should get you afew miles. This method got me going at least fifteen times last week until my pump arrved from Groton. This method is not recommended if you are doing a lot of inner highway work as it would be unwise to break down on a freeway in the centre lane and try to pull over. On a similarly equipped Audi 5E I owned 12 years ago i used the headlight washer motor to spray cold water from a camping water holder on the fuel pump via a hole drilled under the rear seat (heck I was unemployed, delivering pizzas and desperate) Of course the pump will eventually die regardless of how cool it gets as the bearing siezes and the internals fry with the extra heat and load of not spinning freely. The other suggestions of fuel relay are worth looking into if cooling the pump down has no effect.

 

Just one question...are you using a metric super soaker or an SAE model?

 

Hmmm lets see now it says: Wing Chung Toy Company, Made In China. There is no mention of whether the jetsream comes out of it in a metric or SAE spray pattern. This one only got me afew miles down the road so perhaps it's an out of date Whitworth.

 

when i was a kid i had a 77 280z that would do that, it was the fuel pump.
maybe i can help someone here help you since i dont know the specifics of the 740 and it has been a while since i had my 760 turbo.
there should be a way to make the FP run. they usually run for a few seconds when you turn the key to on. or, perhaps you can pull the connector on the AFM and jumper the 2 pins on there to make the FP run. i dont know if these AFM's have the contacts that keep the FP off if there is no air flow into the motor. the older AFM's with the flappers had them.
try wiggling the engine wiring harness. perhaps you will get lucky and find a wire that is grounding out. for that matter make sure you have good grounds, engine to chasis and battery. run your hands all over the harness, check connectors, make sure they are plugged all the way in.
i know this is strange, but have you been running the AC? my 960, and my moms did this, when the AC comp would cycle, it would momentarily cut off the car, also did it on a jeep i had. i had to pull the plug on my low pressure switch on a trip and jumper the comp on to keep it from doing it, but it never kept the car from running.
could also be the computer. maybe a bad solder joint. i have repaired several BMW computers, one may have been a solder joint, not that you can fix this on the road without putting in a new computer.
does your car have a crank position sensor? they can be intermittant.
any vacuum hoses that could keep it from running?
good luck

 

Sofob, did you ever make it home? You never mentioned if the car had battery power when it died - did it?

My 850 died two seperate times on me. Konked out doing 70 down the highway at night - freaky. The engine sputtered and the dash lit up. The starter would crank it over, but it woud never catch. Turns out it was it was the fuel pump... and $750 for parts & labor. I don't think this is your problem 'cause when the pump goes, it's gone!

The other time I was driving in evening rush hour - with snow coming down, no less - and the whole thing just died. No engine, no lights, nothing. REAL freaky. Turns out that I had just bought a new battery a few days before and the grease monkey lost the bolt that secures the clamp to the + post, so the clamp was actualy wiggling around the post, sometime making contact sometimes losing contact. Just had to grab a 50-cent hose clamp and that did the trick.

Keep us posted . . .by posting . . .