car died on freeway, now wont start

[Reeves]

Hey guys it seems I need some help once again. I was on my way up to LA when my car just died on me. The car had been randomly'surging' or 'bucking' in the past when I was low on fuel, but operated perfectly when I filled up the tank. It was such a rare problem though that I decided to forget about it until it started to get worse, but it never did, and if anything the symptoms seemed to get better. Well before the car died it started to surge slightly, but not nearly as bad as it had in the past, as if someone was playing with the gas, and then ran perfectly for another 30 minutes until it just completely died out of nowhere, on a nearly full tank of gas..

Now I'm not entirely convinced that the symptoms I described are related to fuel, but that would be my first guess. When my friend tried to test for spark on the highway he said he didn't see any, so at this point I'm thinking it could be anything. In a little bit ill be doing some more thorough testing and try to fix the problem, but I was hoping to get some opinions or advice before I get started.

Everything I said above aside, what could cause my car to just die like that? I have power and the car cranks great. I've never had to diagnose anything like this before but so far I'm thinking it could be one of the following:

Fuel pump
Crank position senor
Coil Fuel
pressure regulator

I have a 85 325 parts car in my garage so I have a bit to work with.. What parts from it can be used on my 87' 325is? I believe the fuel pumps are the same, but what about the CPS, coil, and fuel pressure regultor? And also if you guys have any tips on how to diagnose what my problem is I would appreciate it. Thanks

[freeride53]

fuel pump.

[jlevie]

The first step in diagnosis is to determine if there is spark when cranking over the engine. No spark at the coil wire could be:

No power to the coil or bad coil
No power to the DME (main relay, fusible link) or a bad DME ground
Bad CPS
Bad DME

Spark at the coil wire but not at the plugs could be a bad distributor cap/rotor or a broken timing belt.

If spark is present at all of the plugs, the fuel system is the next likely candidate. The pressure & delivery tests in the Bently will tell you where any problems are.

[Reeves]

Well I tested to see if the fuel pumps were pumping fuel by disconnecting the hose after the fuel filter. When I cranked no fuel came out. So I took the pumps out of my 325 parts car and installed them and I still have no fuel coming out of the hose. I can hear the main pump over the fuel filter working but can't hear anything from the pump inside the tank..

I'm gonna check the relay but I don't know which relay it is and my hanes manual doesn't say.. anyone have a fuse/relay diagram? I really need a bently..

[Dj Buttchug]

If you need a fuel pump hit me up. I have a new pump for sale. 30 bucks

[LJ851]

I think you are on the right track. fuel problems are usually smoother than ignition problems and your description sounds pretty smooth. Buy a bently ,you wont regret it.

[e30rapidic]

my vote goes for the main relay.

[einstein57]

If you need a fuel pump hit me up. I have a new pump for sale. 30 bucks

If it is in fact new I'll take it.

[Reeves]

Could the main relay be the culprit if all the warning lights come on when the key is turned to ignition, and if the car cranks?

[jlevie]

Could the main relay be the culprit if all the warning lights come on when the key is turned to ignition, and if the car cranks?

Yes. The main relay has nothing to do with the lights or starter. It only provides power to the DME.

[Reeves]

How do I know which relay to use? My main doesn't indicate what what volts and amps it is like all my other relays..

[norcalE30]

im having the same problem with slightly different symptoms... mine died on the freeway, but it lurched violently a few times then started slowly losing power. hitting the gas only made it die more... im guessing fuel pump as well, any more ideas?

[jlevie]

That sounds like it could be the fuel system. The fuel system tests in the Bentley will tell for sure.

[Reeves]

Well I finally got around to working on it again and am now a bit more confused as to what is wrong..

Basically both main pumps I have worked (my spare, and the one that was in the car when it died) and both of the feeder pumps seemed NOT to be working wen I connected them directly to the battery. So I should still be getting fuel, but the problem doesn't seem to be with the pumps anymore but instead the power to the pumps.

About a week ago before a big rainstorm hit I tested the relay by bypassing it completely and jumping terminals 87 and 30, and I could hear the pump working. The car still did not start however, and I believe it was due to not having the correct main relay installed as I used the 4 prong relay out of my parts car instead of the 5 prong that is in the car I'm trying to fix on accident, which I didn't discover until I started working on it today. Well when I went out today and jumped terminals 87 and 30 again, I did NOT hear the pumps working despite confirming that they do indeed work when directly connected to the battery.

So I can't seem to get power to the pumps despite bypassing the relay.. what could be the problem? Could it be the fuse? I Checked them but they all seemed to look fine, but I'm not quite sure which fuse is for the fuel pump, and not even my crappy Hanes manual tells me..

I'm running out of ideas here and really need some help. Thanks guys.

[RagtopE30]

The main relay has 5 prongs. You can bypass the main relay for a short time in order to diagnose the problem. If the main relay isnt sending power to the fuel pump relay it will not matter if you jump the fuel pump relay or not. Try jumping the main relay by jumping 87a and 87b to 30. You should be able to start your car. If it starts you need a new main relay. The main relay should be next to the fuel pump relay, IIRC it is the only one of the three with 5 prongs.