Fuel pump / wiring woes

[Travis_WA]

Alright. So to continue my thread from a couple weeks ago:
http://www.bimmernut.com/forum/showthread.php?t=39671

I decided to test the connection in the trunk and found the positive had continuity to ground, which concerned me. But being a noob with a DMM and the car still running fine, I left it alone thinking perhaps it was truly the filter or something else.

And of course, my car is now sitting in the parking lot at work because it wouldn't start again. This time the stereo made a static noise a bit before the car died, I played with the connection in the trunk, tried to start it again, and the fuse presumably popped at this time because it stopped firing at all. I'm thinking maybe the stereo noise had something to do with a wire grounding out? Does that make sense?

Fuel pump fuse is now blowing every time.

Looks like the connection from the wiring harness to the fuel pump was replaced at some point - the original wiring is taped up to the new connector - and I'm thinking if it was shorting out this would be the first place to check.... So tomorrow I'm going to take that apart and see if its the cause. Otherwise I have no ideas and really hate to pay for a 2nd tow to either the mechanic who failed to fix it the first time, or a new one I don't know at all.

Tired of this.

On the brighter side, I did find a replacement sun visor today at the wrecking yard.

[Dave M]

Hey, congrats on that sun visor :D

I'm interested in this new connector at he pump. do you have pics? And when you say, "it stopped firing at all', do you mean the starter quit working or the pump quit working? Obviously, theres a big difference.

Other than that, my only advice is to find a used fuel pump (from a reputable source) and see if that does it. Unless someone here can troubleshoot a potential electrical gremlin on the www, it migh be worth it to swap out the pump.

Like i said, I had similar issues (not quite as bad) and after finding a used pump from a board member, its been smooth sailing. Knock on wood.

Dave

[shogun]

I wonder how long a used fuel pump can be stored. Last weekend I tested 2 fuel pumps from a parts car E32 750. We disassembled the complete car and the fuel pumps were just stored in a shelf still assembled in the brackets and attached to the lid of the fuel tank (but outside the tank) for about 1 year.
Just out of curiosity I tested them. Both pumps clicked, but did not move, they were stuck.
I had the same on some other 750 we have in our warehouse, pumps were stuck.

Then I checked the package of a new Bosch fuel pump I have here on stock. This pump is in a sealed plastic bag, and it looks like inside there is a lot of oil or something which keeps the pump greased.
How to properly store a used fuel pump?
In any case I would be very careful to buy a used pump, if that has been stored a long time, it is also stuck. Some pumps in our warehouse 750 we could manage to get them running again after trying again and again to start them with a battery and the pump was connected to 2 PET bottles to run it with fuel in circulation (no dry run). We also whacked then on a wood piece and they became lose again and the also worked fine.

[Dave M]

I wonder how long a used fuel pump can be stored. Last weekend I tested 2 fuel pumps from a parts car E32 750. We disassembled the complete car and the fuel pumps were just stored in a shelf still assembled in the brackets and attached to the lid of the fuel tank (but outside the tank) for about 1 year.
Just out of curiosity I tested them. Both pumps clicked, but did not move, they were stuck.
I had the same on some other 750 we have in our warehouse, pumps were stuck.

Then I checked the package of a new Bosch fuel pump I have here on stock. This pump is in a sealed plastic bag, and it looks like inside there is a lot of oil or something which keeps the pump greased.
How to properly store a used fuel pump?
In any case I would be very careful to buy a used pump, if that has been stored a long time, it is also stuck. Some pumps in our warehouse 750 we could manage to get them running again after trying again and again to start them with a battery and the pump was connected to 2 PET bottles to run it with fuel in circulation (no dry run). We also whacked then on a wood piece and they became lose again and the also worked fine.

So, one should always buy a piece of wood with every used fuel pump ;)

Good to keep in mind when thinking of anything used that has sat for a while. The pump I bought was from Jon K and hadn't sat for very long at all.

Dave

[Ross]

I wonder how long a used fuel pump can be stored. Last weekend I tested 2 fuel pumps from a parts car E32 750. We disassembled the complete car and the fuel pumps were just stored in a shelf still assembled in the brackets and attached to the lid of the fuel tank (but outside the tank) for about 1 year.
Just out of curiosity I tested them. Both pumps clicked, but did not move, they were stuck.
I had the same on some other 750 we have in our warehouse, pumps were stuck.

Then I checked the package of a new Bosch fuel pump I have here on stock. This pump is in a sealed plastic bag, and it looks like inside there is a lot of oil or something which keeps the pump greased.
How to properly store a used fuel pump?
In any case I would be very careful to buy a used pump, if that has been stored a long time, it is also stuck. Some pumps in our warehouse 750 we could manage to get them running again after trying again and again to start them with a battery and the pump was connected to 2 PET bottles to run it with fuel in circulation (no dry run). We also whacked then on a wood piece and they became lose again and the also worked fine.
"We also whacked then on a wood piece and they became lose again and the also worked fine."
Crude but effective. Just like the window motors

[Travis_WA]

Hey, congrats on that sun visor :D

I'm interested in this new connector at he pump. do you have pics? And when you say, "it stopped firing at all', do you mean the starter quit working or the pump quit working? Obviously, theres a big difference.


Thanks.

By stopped firing I mean I think the pump quit because the fuse blew. Previously it would start and run for a second or two before dying (the car, that is. couldn't tell if the pump was actually going or not from the drivers seat). After I jiggled the connection a bit it stopped doing that and just cranked without firing. I'll take some pics in a couple hours when I go over there after class.

[Dave M]

Thanks.

By stopped firing I mean I think the pump quit because the fuse blew. Previously it would start and run for a second or two before dying (the car, that is. couldn't tell if the pump was actually going or not from the drivers seat). After I jiggled the connection a bit it stopped doing that and just cranked without firing. I'll take some pics in a couple hours when I go over there after class.

Still a bit confused. When you say "it stopped doing that", do you mean the pump statred working or the starter starter working. Unsure whether its isolated to the pump or electrical gremlins are buggering your entire ingition/car. Again, if your pump is intermitently working, you may be in need of another.

One other thing to try (and I've done this) is rig your DMM with long extension wires so they reach from the cabin to the pump power supply wire in the trunk. Now you can watch it while you're attempting to start. Ooooh, ahhhh, what fun :D Ya never know...........

Dave

Dave

[Travis_WA]

Still a bit confused. When you say "it stopped doing that", do you mean the pump statred working or the starter starter working. Unsure whether its isolated to the pump or electrical gremlins are buggering your entire ingition/car. Again, if your pump is intermitently working, you may be in need of another.

One other thing to try (and I've done this) is rig your DMM with long extension wires so they reach from the cabin to the pump power supply wire in the trunk. Now you can watch it while you're attempting to start. Ooooh, ahhhh, what fun :D Ya never know...........

Dave

Dave

The starter never failed, its just that the car would start and run for a second or two. After the wire jiggling, it would do nothing except crank.

Going over to look at it now, good idea with the extension wires... I tried making a jumper for the fuel pump relay as per the bentley but haven't had much luck with that one.

[Travis_WA]

Appears the fuel pump is bad. Wiring looks fine at the connection and I can see no other reason its blowing a 15A fuse. Tow truck is on the way again. -_-

[Travis_WA]

Final update on this (hopefully):
New fuel pump, car running fine again, even seems to have a little more power.