Strandeed... Think it's a fuel issue

[Bimmerman325i]

Hi all, my 89 325i just decided to strand me, not 30 minutes after I had just driven it. I drove it from work back to school to work on the SAE car(5 min drive), then went back out about 30 min later and the car won't start. It has plenty of power, is cranking over just fine, has oil, has spark, but still won't start. It has 3/4 full tank of gas.

When I started the motor it ran fine for a couple seconds, then the rpm dropped down to 500, and no matter how much gas I gave it it stayed at or below 500 until it quit. This took about 10 seconds at best. I've been trying to crank it but still no luck; I've waited for a few minutes in between in case I flooded it but still nothing. Occasionally it will try to start(sounds like it's burning vapors) but then keep cranking without turning over.

So: what do you guys think the problem is? Fuel filter or fuel pump? How easy/expensive is it to replace either, and where can I find either component. I've had the car for a month and have done nothing to it except a couple tanks of good premium(91) gas.

This all has happened in the last hour and a half. I've called AAA and they're on their way with a flatbed to take me & Katja(car) home. :curse::sad:

Thanks in advance!

[jlevie]

That does sound like a fuel system problem. You could try jumping the fuel pump relay and see if you hear it run, but otherwise you'll have to replace the filter and do a pressure check to see which may be at fault. But then the problem could just be a bad fuel pump relay.

[Bimmerman325i]

Where is the fuel pump relay? I don't have an OE/Bentley manual for my car(on order) and my fuse box doesn't say which goes to what.

Also, I plan on replacing the filter- how do I get rid of the air bubbles in the line after replacing it? Do I need to?

[Justin B]

FP relay is the middle relay of the three under the plastic cover directly to the left of the throttle body. About a foot or so forward of the fuse box. To jump the relay I think its pins 30 and 87, regardless its the pin closest to the fender and the forward most one. I just did this with my car a week ago.

Dont worry about the air. It'll either pump through or not be enough to matter. I just replaced my fuel pump, which emptied the line a little of fuel, and didn't need to prime it at all.

FWIW, my fuel pump didn't let my car start at all. Could be the relay is acting weird, or the fuel pump became intermittent. Open up the access port to the fuel pump under the seat and give it a good smack while trying to crank the car over. My old pump works just fine, and externally testing it is now pretty consistent on/off, but when I was testing it out of the car and it didn't start spinning with 12v, I just tapped it lightly on the ground and it would start whirring away. Maybe a wire is loose or something that makes it run only sometimes while on? Check the amp draw for the fuel pump too, see if its erratic or low. I think it's supposed to be pulling 1.6A. Plenty of things to check anyway...

[redhatpat]

FP relay is the middle relay of the three under the plastic cover directly to the left of the throttle body. About a foot or so forward of the fuse box. To jump the relay I think its pins 30 and 87, regardless its the pin closest to the fender and the forward most one. I just did this with my car a week ago.

I just did this too and I'm pretty sure its the pin closest to the fender, but then the pin opposite it, closest to the engine? Pin #s 30 and 87 sound right. Anyway, I couldn't hear the pump running, but I could definitely hear the fuel running into the fuel rail.

[wagonizzle]

My fuel pump died the exact same way. We got it home and pulled the rear seat and banged on the area with a rubber mallet and the car started and ran fine. Fuel pump. Cost is around $220 for a whole new assembly, and the filter is cheap. Replace the lines when you do the filter. Make sure to ask for fuel injection hose and get new clamps. Easy job. Good luck

[chivas]

fuel pump died on my other iX which was used as colladeral for a loan.

car drove drove drove and started to sputter and finally, death. quick change of the pump and it ran just fine.

[ZiMMie]

it could also be the ECU.

[Bimmerman325i]

Hey thanks all for the replies. I unplugged the fuel pressure regulator and cranked it: no fuel came out except for what was in the line. I then unplugged the line below it that runs directly into the fuel rail: no fuel came out while cranking.


I then removed the rear seat and uncovered both the fuel pump


and something else.


I verified that all electrical connections are working, and then cranked the motor: still nothing. I then cranked it while tapping the pump, and it fired right up.

I let it idle while I collected my tools and then turned it off to start it again. Another success. I repeated this a couple times, revving it to about 3k rpm to vary the load on the pump and fuel system. A few minutes later(on the fourth on-off cycle I think) the car fired up, ran fine, but then started idling funny and pretty low(650 or so rpm) and begun hesitating when I tapped the throttle. I had my dad look at the engine bay while I was working on it, and he said the red circled thing had been popping in and out a few mm when the car was hesitating. The blue circled thing has been buzzing loudly.... any problems with that and what is it?


I figured since it's not part of the fuel system as far as I know I wouldn't worry about it. I killed the motor and started it again to see if the hesitation/sputtering was repeatable, and it was.

The motor started fine, then began idling really really low(500 and below) and then quit. It would not start again until I lightly tapped the fuel pump again while cranking the motor, and then it started up just fine. The hesitation issue is something else; I'm pretty convinced it's not related to the fuel pump issue(am I wrong on that?)

I was talking with my dad after and he thinks it's either a dying pump or a fuel pressure regulator. His e28 535i had the same sputtering and dying symptoms and had to replace the FPR-- although he and I both agree that tapping the pump and having the car start is kinda weird and suggests the pump is on its way out the door.

Which do you guys think is the most likely culprit? FPR or fuel pump? How easy is it to replace the pump? Would I need to drop the tank or is it possible to replace from the opening under the rear seats? Finally, what is the circled thing in the picture and the other thing I uncovered under the seat? Thanks!

[chivas]

pump

[Justin B]

Certainly the pump, no fuel came out of the regulator overflow, and especially if you were able to tap it and it started again. BTW, the thing on the driver side of the fuel tank is the secondary fuel level sender. There's two in our cars.

[jlevie]

The blue circled object is the Idle Control Valve. A buzzing from it with the ignition on is normal. The aluminum part in the red circle is a hose adapter that was pressed into the manifold. Over time that connection will loosen and become an intake leak. I've had good success repairing that with JBWeld. Just be sure to throughly clean the adapter and bore with solvent to remove all oil before applying the epoxy. Mineral spirits followed by acetone does a good job.