No-start condition, need diagnostic help

[nharperc]

I have a no-start issue and I'm looking for a consult on diagnostic next steps.

The following items have been verified:

• IAC buzzes with key on
• Engine cranks but does not start
• Verified spark at coil
• Verified spark at multiple plugs
• Fuel pump runs when relay is jumped
• Fuel pump runs when engine is cranking
• Fuel makes it to the rail, through FPR and to return line
• Fuel pressure between pump and FPR is 45 psi
• Test light shows power to the injector harness

Concerns:

• After cranking I pulled 3 different spark plugs and all were dry. This indicates fuel isn't being sprayed into the cylinder. Possible causes include low fuel pressure or injectors not being pulsed.

Next on my list:

• Confirm injectors are being pulsed by using noid light
• Check resistance of CPS, looking for 500-600 ohms

Am I missing something obvious or does anyone have additional recommendations for diagnostics? Would you suspect the DME relay?

[tcheb]

If you're getting spark, the CPS is most likely not the issue. What year and model is your car? Some E30s have two fuel pumps. One inside the tank and one underneath.

I had a crank no start issue recently as well but it turned out to be a combination of two things that gave out at the same time: the Fuel pump main relay and the in tank fuel pump.

This guide helped me find the issue:

[nharperc]

tcheb, the chassis is a 90. Thanks for the e30zone chart, I ran through that again and it's really down to "Check for power at injectors." I have power to the injectors but I can't verify the ground pulse.

[ForcedFirebird]

Did you try ether? If you remove the 10mm hex screws from the fuel rail, you can lift it out of the manifold and observe if they are actually spraying. In fact, before pulling the rail, use a stethoscope (or long screwdriver handle to your ear, pointy end on injector) and listen if they are even energizing.

Without knowing the history, it's kind of a shoot in a dark. Cars that sit for extended period? How old is fuel, maintenance etc?

[nharperc]

ForcedFirebird, I'll try the screwdriver trick to see if I can tell if they're energizing.

My next thought was to pull the injector harness, pull the #1 plug, jump the fuel pump relay and run 12v to the #1 injector. If the injector is working I should hear/see/smell fuel coming from the #1 spark plug hole.

As for history, this is a new to me engine with an actual dyno history. It from a car that wrecked less than two years ago. When I refreshed the engine I pulled the injectors that came with it and replaced them with my own set, which came off my old engine 4 months ago.

[nharperc]

I picked up a noid light test kit from Amazon which allowed me to confirm the injectors were not pulsing while cranking the engine. This led me to connector C191 where the injector harness ties in to the engine harness.

Having reverified the injectors are getting 12v, this left the ground wires as culprits. Motronic has grounds for injectors 1, 3, 5 on one pin, and injectors 2, 4, 6 on another pin. I found diagrams showing these pin outs but none seemed to clearly show the orientation of the connector. A few minutes with the multimeter confirmed pins 6 and 7 on the injector harness are the pulse grounds. Those contacts were cleaned and I moved on to the engine harness.

The engine harness showed some signs of corrosion, and doing a continuity test to ECU pins 16 and 17 to ensure a good connection confirmed there was a problem. C191 on the engine harness side was cleaned to ensure good electric contact, and reinstalled.

With the wiring presumably in good working order again, I reinstalled the noid light and cranked the engine. Success, flashing noid light!

Finally, I reinstalled the intake boot and everything necessary to start the new engine for the first time.

TLDR: no start solved by removing corrosion from C191 pins so the injectors pulsed properly.