M42 Full Rebuild now won't start

[bmwman91]

I forget, did you replace the coil packs? They can do weird stuff like not fire if they are failing, depending on if they are hot yet.

Otherwise, it sounds like the carbon track on the AFM is going bad. Can you borrow a known good one and try it?

[theTBLACK]

Anyone still subbed to this thread?

The car runs and idles great, but starts to sputter around 2.5 rpm.

If you let it warm up for 20 minutes, it revs just fine all the way up.

Any thoughts?

Thanks guys!

[Cephas]

Quick update - After taking off the exhaust, the car did in fact run. We didn't rev the motor very high as we couldn't hear the valve train. Anyway, we had a new cat welded in at the exhaust shop.

On the way back from the exhaust shop with the exhaust back on - we encountered an issue that we were experiencing before the rebuild.

When I first got the car it would run, and idle fine. But upon giving it gas and accelerating up around 3rpm, it would lose power and die.

This same problem is now occurring - i'm thinking that the exhaust may be clogged somewhere other than the CAT now as the whole system is aftermarket -

I'm going to take off the exhaust tomorrow and see if that solves the problem.

I'll get a video tomorrow and share it here!

Looking forward to the video.

Also for others chasing down similar issues: my 89i track car will not prime the pump with the key in the "On" position. Only during cranking. Also, for what it's worth, it will not prime the fuel pump even if I jump it.

Good luck with your car!

[theTBLACK]

Quick update - After taking off the exhaust, the car did in fact run. We didn't rev the motor very high as we couldn't hear the valve train. Anyway, we had a new cat welded in at the exhaust shop.

On the way back from the exhaust shop with the exhaust back on - we encountered an issue that we were experiencing before the rebuild.

When I first got the car it would run, and idle fine. But upon giving it gas and accelerating up around 3rpm, it would lose power and die.

This same problem is now occurring - i'm thinking that the exhaust may be clogged somewhere other than the CAT now as the whole system is aftermarket -

I'm going to take off the exhaust tomorrow and see if that solves the problem.

I'll get a video tomorrow and share it here!

[Dj Buttchug]

holy ballssssessss

[jpod999]

Damn, that's backpressure for you! I wasn't far off in my kink in the line suggestion a few pages back, I just had the wrong system!

[Gkwan]

I think you owe us a video of it actually running!

Congrats on getting it running!

[bmwman91]

Lol

Holy hell, that was unexpected!

[theTBLACK]

IT RUNS!

The exhaust was clogged and it needs a new catalytic converter. The engine couldn't breathe.

[bmwman91]

Weird. Maybe the old ones had some bad fuel in them or something and got varnished shut when they were sitting. It sounds like you should have a working vehicle soon!

[theTBLACK]

Last night I installed 4 rebuilt injectors.

Hooked up the rail - covered the injectors with ziploc bags.

When cranking, all of them were firing fuel. So the old injectors somehow all went bad at once - or something weird is going on.

Either way, i'm dropped it off at a trusted shop and i'm let them figure it out.

I've dumped many hours and too much money into this 4 cylinder motor, hopefully they can figure it out relatively quickly.

I'll keep you posted!

[theTBLACK]

remember that motronic will not always prime the fuel pump when you key on...

Yeah mine never does. I replaced the relay with a new one for good measure and I'm installing the remanufactured injectors.

Tuesday I'm taking it to a professional - I've given up.

[Dj Buttchug]

remember that motronic will not always prime the fuel pump when you key on...

[theTBLACK]

I'll give that try.

If any of you guys read this this morning, the fuel pump is not kicking on as it should when you turn the car on.

I'm almost 99% sure that when you turn it right before cranking, the fuel pump primes. Mine isn't doing that and I don't know why.

I'll try hooking up the injectors and seeing if I feel anything - because at this point, I'm not sure what else to do in order to get them to fire.

If you have any other suggestions for today, let me know as I'll be at it all day today.

I'm going to check the fuel pressure at the feed line where it comes up from under the car and make sure I have good pressure there.

[jpod999]

Yes, the fuel pump seems to be working properly in his car.

From one of the OPs post on the previous page though it sounds like the fuel pump doesn't kick on when turning the key. In my car, when you would turn the key to Ignition I always heard the pump kick on before turning all the way to Start.

This post:

Okay. I'll try that next.

Can you speak at all to the issue of the fuel pump not coming on when I turn the key to the run position?