OBD-I s52, has spark and fuel, but won't start

[e30m20TurbO7]

Did anyone figure this out I’m stumped at on a car at the moment and about to Pull a trigger and give up on life

[samiam3356]

Any luck on this?

[rneedham1979]

It has to be something telling it not to fire, IE the DME is recieveing a bad signal, cam or crank sensor, bad ground, not enough voltage or a pinched, crushed wire. If your only getting 10v in the fuse box, you probably have a voltage issue at the DME, they should all read atleast 12v.

[JGood]

Correct



Incorrect afaik. I diagnose you connecting the harness up wrong. Having just done the same as you, they are the same plug.

If you are 227% sure they are different plugs (a possibility over the years etc), what crank position wheel are you using? the S52 one or an M/S50 one? you need to use the latter with OBD1 wiring, as the guide pin is in a different place and may even have different amounts of teeth.

I saw it with my own eyes. The two plugs that route to the crank and cam position sensor plugs are different. One is male and one is female. I also verified this on the old harness.

He's using the same crank wheel that he used when he pulled the engine out of the other e30. None of that changed. I'm not familair with the OBD-I swap, but whoever converted it, did it properly, as the car ran great in the other e30.

No, they are not. One is female and the other male. Knock sensors are both the same.

Edit: You said in the first post you tried a different FPR. Are you running the OEM FPR on the rail or aftermarket? I think it will have to do with the wiring on the harness. Will be interesting to see the final verdict.

Nope, stock FRP. The reason we swapped it is because it looked like the old one was damaged, it has a small dent in the casing. So I swapped another OBD-I 3.5 bar FPR and fuel rail on.

[samiam3356]

No, they are not. One is female and the other male. Knock sensors are both the same.

Edit: You said in the first post you tried a different FPR. Are you running the OEM FPR on the rail or aftermarket? I think it will have to do with the wiring on the harness. Will be interesting to see the final verdict.

[ethrty]

Are your CPS and and Cam sensor mixed up?

It's easy to mix those two up, they are the exact same plug.

Correct

They aren't the same. One is female, one is male. If you mix them up, you'll be connecting the cam and crank sensor to each other and the engine harness to itself.

Incorrect afaik. I diagnose you connecting the harness up wrong. Having just done the same as you, they are the same plug.

If you are 227% sure they are different plugs (a possibility over the years etc), what crank position wheel are you using? the S52 one or an M/S50 one? you need to use the latter with OBD1 wiring, as the guide pin is in a different place and may even have different amounts of teeth.

[M-technik-3]

Man so much for the easy swap over...one for one huh? Same thing happened with me on my E36 328is swapped out a M52 for an S52 and turned out the engine on that had a blown headgasket as well. Sucked ____.

[JGood]

Checked your harness wasnt kinked ,checked continuity from connectors to dme main connector pins,could be defective harness ( anything can happen).not wired right(nothing against zionsville) .

That's what I was thinking, and will probably be the long and tedious process right after the compression test.

Thanks!

[VEGETA7]

Checked your harness wasnt kinked ,checked continuity from connectors to dme main connector pins,could be defective harness ( anything can happen).not wired right(nothing against zionsville) .

[JGood]

Fuel filter, pump?

Could have worked before and somehow take a shit at the same time, I guess. Seems like everyone is throwing darts I just wanted to throw some to.

There is fuel coming out of the return line. That means it's getting pressure, and enough of it too.

[samiam3356]

Fuel filter, pump?

Could have worked before and somehow take a shit at the same time, I guess. Seems like everyone is throwing darts I just wanted to throw some to.

[JGood]

Swapped relays, no go. As stated multiple times, fuel lines are hooked up correctly, and I swapped them and tried it anyway, still no go.

We're going to do a compression test next.

[jahnaboi]

Mixed fuel lines (spark plugs still get wet that way) or mixed up relays/bad relays. Its one of those two.

[JGood]

You guys are over thinking, the engine ran before and was untouched. My engine had the same exact symptoms, back firing and all and it was the main relay.
Not sure if it was mentioned, fuel feed line connected to the front of the rail right.

Yes, feed to the front. Tried it the other way just for the hell of it.

With the return line unhooked, I'm getting fuel spraying out while cranking. That means the rail is pressurizing and the regulator is letting the excess out, so it's functioning.

I am very interested in the main relay though. I will try that ASAP.

[Danny]

I think G&T may be onto something