m20: spark and fuel no start

[rede30]

On a 90 325i vert. Original motor seized do to a broken oil pan. I sold the motor to my friend who owned the car and he had a shop put it in. My friend was going to sell the vert as soon as it was running again because he didn't want a vert for college. It worked out that I traded him a sedan for his vert after most of the work was done on the motor swap. The shop that did it couldn't get it to fire right away but didn't put too much time into diagnosis.

The car won't fire. It sometimes rumbles a bit for a sec or two but nothing past that. I have spark to every cylinder. Fuel to every cylinder. I have gone over all the work and it looks good. CPS good, DME good, all intake lines are good, if I have an intake leak it is small and would still let the car fire. To me it seems like my timing is off by a tick but I just checked and it is dead on. I did a t-blet on the motor before I sold it to my friend so I thought it was possible the timing would not be on but it is. I want my timing to be off because this is the only thing that is logical to me but I can't think of a single place for error for lining up the marks, sprocket and pulley can't really go on wrong.

So If I have spark and fuel, what could be causing my motor to not fire? DME is for sure good.

[rede30]

grounds are good. relays are good. FPR holds pressure in the rail. injectors get power for sure and I think they ground because all the plugs had fuel when pulled. The harness is all plugged in correctly as far as I can tell, I know their routes well.

[jlevie]

If you have spark on all cylinders, correct rail fuel pressure (proved by a gauge) when cranking, cam timing correct, and injector firing (proved by a noid light) a failure to start will then most likely be incorrect spark plug wires, intake leaks, a bad AFM, or a bad DME.

[stamar]

it can be cylinder leaking. head gasket.

no compression.

[Myster-E]

Try swapping the CPS connector with the impulse sensor connector located on the driver's side near the front of the intake.

[rede30]

Try swapping the CPS connector with the impulse sensor connector located on the driver's side near the front of the intake.

This is the first thing I checked since after my first motor swap I had these switched. Wish it was it.

I went over compression today and had 135-150. Not great but it was a cold motor with a cheap gauge so give or take. Good enough to run.

I know I need to get a fuel gauge on the inlet and outlet of the fuel system but I have not had a chance to get a new gauge since running my old one over. I did take the fuel rail from a running parts car I had and tossed it on but nothing changed.

The car will come to life some times but only for a sec or two. If I pull the FP relay it will usually fire until fuel goes away. kind of makes me think I have too much fuel but what could cause this? FPR, but again, even thought I don't have a gauge on it came directly from a running car. I checked to see if my fuel return was plugged but I could blow the gas easily through the line and into the tank.

What could cause too much fuel? If this is my case. If I don't burn gas that goes into the chamber I get a lot of gas in my oil don't I? I never really thought if this. Or does gas not pass the rings?

[5Toes]

lol... are you out of gas by chance? If you think there is too much fuel, clmap the line to the rail half way with vise grips, worked for me when my fpr was broken

Happened to me..

[Gregs///M]

Yes, the FPR can be bad and if your getting too much fuel your spark plugs would be all wet. A bad AFM can cause a no start condition. Also be sure your TPS is adjusted correctly so it will trigger the ECU and ICV that its should run at idle speed. Check your ignition coil resistance and input voltage unless you know 100% you have spark.