E32 750iL questions to electronic gurus (long)

[Whit]

Shogun, did your friend figure out if he had a bad fuel pump or bad connections or something else?

[shogun]

Got the following email:

Erich & Mike,

The car is running!!!! It is amazing what happens when you get a working
part. Thanks for the help that you and Mike have provided.

This is what i posted on Roadfly this morning:

The problem has been solved it was a fuel pump. The new fuel pump that I
purchased was defective which caused the fuse to blow. This did not occur to
me as a possibility at first so I assumed it was a short somewhere else.

In the future I suggest the following in troubleshooting a rough running
engine with no power and hard shifting. Bear in mind this is what I found
would have helped me resolve this problem more quickly:

1. Check and see if the EML light turns on during start up - No EML suggests
Limp mode;
2. If you are not in Limp Mode check the exhaust pipes between the engine
and CATS - helps identify if both banks are running;
3. If one side is hot and the other is cold than I considered the problem to
be fuel or spark related. Check the fuel supply by following the procedure
to check if fuel is making it to the engine as detailed in Johan & Sean's
webpage at:
http://bmwe32.masscom.net/sean750/fu...Regulators.htm

If no fuel at the engine check the fuel pumps as detailed at:
http://bmwe32.masscom.net/sean750/fu...t/Fuelpump.htm
Note: When I tested my voltage I did not get reading that were similar to
what people suggested I should get;
5. A good way to check the pump is to apply 12V directly to them. Keep in
mind that these are immersed in the gas tank and that the petrol is what
cools them so when testing do not allow the pump to run for long periods of
time. Also, because it is a pump expect a shot of petrol to come out of the
pump, use caution in where this petrol will fly;
6. If there was fuel at the engine as described above, I would consider
spark as the next check;
7. I was able to check the spark by using an inductive timing gun and
attaching the connector to the individual plug wires at the distributor. I
loosened the tubing to the MAF to provide better access;

At this point I had no electrical problem so I will not proceed any further
along this vein. Bentley's does detail a series of tests for the coil and
other electrical components.

I understand that there maybe better or easier ways to accomplish what I
have detailed above,but if this can help one person I'll be happy. Thanks to
all who assisted on this adventure!

Real

[Whit]

Great! He should have swapped that used pump with the known working one a long time ago! That blowing fuse was a good indicator of the bad pump, too. Oh well. Live and learn, eh?

[hgjacobsen]

Have you tried pulling the vacuum lines off of the fuel pressure regulaters? If the diaghram is busted gas will be present where there normally will be vacuum. If there is gas,(my opinion), you would not build up enough pressure to activate the injectors, you'll be running rich due to gas being sucked into the intake and therefore you'll be smelling gas out the exhaust.
Fuel pressure regulaters should run about $115.-140.00.

I'm running into a silmilar problem and recently replaced the fuel pressure regulater,fuel pump and a MAF sensor (not to mention new cats and O2's). I've been told by a lot of old school Bimmer mechanics that it may be an intake gasket leak. Sucking air, causing it to have a rough idle, run rich, etc.
The codes I was pulling were not consistent. I think if it has to do with fuel there will be hardley any codes ( my reasoning is that there are no sensors that tell the computer if there is enough fuel pressure either at the fuel pump or at the regulater). Also nothing to tell the computer if you have a physical problem such as a leaking gasket.
I'm open to suggestions, hopefully I've given you some help.
Henry

[shogun]

Henry,
the car runs again. It was a defective fuel pump. The first replacement pump (used) was also defective. I have tested the car and it was still running on 6 cylinders, no big difference in idle compared to 12 cylinders running. Amazing.
Only when I drove the car one could feel the difference.
I have now made a test: removed the plug/connector at running engine from one MAF, idle just dropped for a second and then the car runs as if nothing happened. Only when you drive the car you feel that not 300 HP are there, but still can be driven.

[shogun]

cat info for Japan spec. BMW owners

Japan was one of the few markets that required temp sensor on the back of the cats to warn you when the cats are overheating... this isn't a bmw only thing, i'm pretty sure its all cars in the japan market, I've seen a number of gray market toyotas and nissans with the same temp sensor on them. I suspect if you look at japans equivalent to the epa pollution rules for cars you'll see that theres a requirement for cat temp sensors as a safety device. A badly overheating cat will glow cherry red and ignite any paper or grass etc that its parked over.


As someone from Canada asked me this question again as he imported an E32 750iL from Japan and has the cat warning, here is a pic of the special relay for 870 degree Celsius which is located under rear seat driver side
ImageShack® - Online Photo and Video Hosting
Just pull it out and the problem is solved. But you could try to repair it. If you want a used one, you probably won't find these in N.A., I should have some used on stock.
Another solution:
the cable white/purple/yellow goes from this module to another plug on pin 20 to the CCM. If you cut off this cable and connect it to ground, that has the same effect.

Then download these Japanese spec wiring diagrams
https://skydrive.live.com/?cid=c83d0...21955&authkey=

[shogun]

Update info:
p/n 1382095 made by DEGUSSA, Germany. New p/n 61311382095 Thermo switchgear, no longer available new, I found one new at a German shop:
61311382095 Thermo Schaltgeraet 196,10 EUR = US$ 270

Partnumber 61 31 1 382 095
Delivery discontinued by the factory
Production Oct '87 - Feb '94

[shogun]

This 750 is still running, recently someone contacted me as he found this thread thru the VIN search, it is now in Canada