OBD1 M52, Start->stall still/again *Now with video*

[Roysneon]

Had this problem constantly or a while, then it stopped as per this thread:

http://www.r3vlimited.com/board/showthread.php?t=315597

Still doing it. Been driving it daily for the last week, it has happened 3 times since.

Once it started right up after doing this a couple times

Once I let it crank long while holding the throttle part open and after about 5 sec. it took off and ran great

Now it will not do any of the above.

To recap the problem, it starts when cranked, then sputters and dies immediately. Holding the throttle when it starts just prolongs the sputtering, it makes sort of a 'clug clug clug' noise as it does.

If I hold it cranked it turns over as if it's not even trying to start for a second, then there will be a sputter and it turns quicker for a while, but still doesn't start right.

I've checked spark and it's all good there. The only thing I can think is to pinch off the return line a bit to see if that makes a difference, try the fuel pump relay and then finally the pump itself.

I just dropped over $1000 on tires and suspension parts, I really just want to enjoy driving this thing now :hitler:

[Roysneon]

Just went out to it, did what was described above, then while cranking with throttle open it took off, revved up and ran great while I was revving it. Let it settle down to idle, idled quite well for about 5 seconds then stalled quickly and will not restart.

[meanEG]

you do know how much oil is in it right? your fuel pump didn't stay on and fill the crankcase with gas right? I seen you had oil coming out of the dipstick. maybe drain and fill to verify. did you put a fuel pressure gauge on the car to verify that you are not losing fuel pressure? are your fuel lines backwards? the return is the line under manifold on the rear of the fuel rail. regulator is known good? that's what I can think of off the top of my head.

[Roysneon]

Oil level is good, I changed the oil a few days ago. Haven't tried the pressure loss test yet. Fuel lines are definitely on correctly. Regulator is suspect, as is pump and CPS.

[meanEG]

you can back probe the CPS and verify voltage going into the DME to see if it is cutting out. you need to get a fuel pressure gauge. harbor freight sells a cheap one or you can go to autozone and rent one for free.

[Roysneon]

Went out with a booster pack after work. Thing started and died once, I held the throttle half open and cranked it for a couple seconds and it started and revved right up. I think the worst part is that it's intermittent. I'm going to grab a pressure gauge. I don't even remember, is there a schrader valve on the 24v motors?

[justin_l_]

I think obd2 rail does and obd1 doesn't.

[Roysneon]

Well fuck

[Roysneon]

Went outside and played around a bit with it just now. The car starts and runs off of starter fluid, so it's got spark, it's just a fuel delivery issue. Does the CPS run the fuel pump? I jumped the relay and the pump ran the whole time with no change so I don't think it has anything to do with the relay, so I'd say it's the fuel pressure regulator.

If it was the CPS I couldn't see it getting enough fuel to run for a second at all. I know it's the most common thing, but I don't think it is the crank sensor based on that.

[justin_l_]

Injectors firing? Maybe injector harness issue?

[meanEG]

the cps is good. it will not activate the fuel pump relay if it were bad. get a gauge and t it into the feed line of the rail. take the fuel line of and crank it to verify that you are right about the fuel lines not being switched around. if you think the regualtor is bad, pinch the return line off completely with vise grips. do this while its running as well if see if the pressure rises (it should). if it doesnt rise than the pump is not puttingout enough volume. have you checked the fuel filter? bypass it if you are not sure of condition. i suggest running a single in tank pump

[Roysneon]

Did some more diagnosis before work today. The results are:

I definately have the fuel lines on correctly, put the front hose going to the front of the rail into a beer bottle and it half filled it with a few seconds of cranking.

After a small fire (great way to wake yourself up in the morning) I've verified the injectors are firing.

I pinched off the return line as much as I could without removing the wiring cover from the firewall and it didn't change anything.

I took the rear seat out and pulled up the carpet, got the turtle cover off and took the level sender out. I can hear the pump operate as I crank, but it seems to sound different between when the engine is cranking and just before/after it does. As if when the injectors are firing it's bogging down or something. I'm going to see if I can find a known good pump and try it before dropping the money on a new one. And probably pick up a filter while I'm at it.

Thanks for dropping knowledge on me, guys. I'd say I have it narrowed down to the fuel pump or regulator, but if it was the regulator, wouldn't the pinched hose have more of a difference? I think the pump may just be intermittently "weak".

[328ijunkie]

Sounds like a pump. We troubleshooted an idle issue on a car and it was a weak pump after all

[Roysneon]

For the price, I'm looking to find a Walbro 255 to retrofit in. I know I don't need it, but it's going to be about half the price if I can find one in town.

[mpowerful]

I got an e36 pump out of the junkyard. Told em it was a window washer pump. 3 bucks. Hahaha.