Trouble shooting a ghost

dwess32

Registered User
I'm trouble shooting a ghost. I found a killer deal on a '90 sc manual, the only problem is it wasn't running when i bought it. The previous owner said the car started to run poorly and the condition got worse as time went on till he parked it 5 years ago. There is a fairly new engine in the front and someone did a good butcher job of the ABS controller wires, patched in an external relay... That's another problem for later.

I've already replaced cam sensor, crank sensor and DIS module. Dropped the fuel tank and emptied. New fuel filter. Just finished replacing the fuel pressure regulator and upgraded fuel rail hoses. Everything is back together and the engine cranks and only cranks. Every so often I get slight hint of spark and nothing.

I have a code scanner hooked up and the test mode on, KOEO. Then turn the key to on position. I hear the fan cycle on and off and some relay clicks in the back. Next I crank it and it slowly starts. It keeps a rough idle for 3-5 sec and dies. codes I've seen pop up are 6,10,11,90

My question is: Could this be a bad ECM? Is there any way of testing the ECM? Any thoughts of troubleshooting elsewhere?
 
Good morning


I am little bit confused? Does the car start after doing the Key On Engine Off (KOEO) test? In addition to what KMT listed if the engine started but died out I would first suspect fuel pressure and or contamination because the car "sat" for 5 years. One "quick" method you could try to identify a fuel related issue is to use starting fluid. I once troubleshoot a 1990 super coupe manual transmission that sat for 7 years. I changed sensors, harmonic balancer, plugs, wires, among other things. I also drained the tank and added fuel system cleaner with new gas. Engine would not start. Did a fuel pressure test. Failed at 10 psi. Before dropping the tank for a fuel pump I decided to take a sample of fuel at the fuel injector manifold and found "cloudy'" fuel sediment. Drained and again added new fuel and fuel system cleaner. No sediments. Changed filter (again). Flushed injector manifold. Changed Injectors. Engine stated. Have you checked the spark plugs and wires? Check basic timing? Check the harmonic balancer condition? Did you reseal the supercharger "hat" to intercooler connectors? Check valve train (collapse lifter(s)). Any indications of a blown head gasket? If the fan cycled during the KOEO test, the fuel pump primes and you recorded CODE 11 (system pass) the ECM most likely is not the cause of the problem.


Good Luck.
 
The car only starts during KOEO. I changed the crank sensor and noticed the cover was missing, even cleaned the vanes. Harmonic balancer is fine. Plugs and wires are still new. Resealed intercooler tubes. Has new oil. No signs of headgasket failure, no oil or coolant on plugs, no oil in coolant. Dried out the fuel tank, added new fuel and Lusac oil. New fuel filter. Reconditioned fuel rail, blue rubber hoses instead of nylon.

Didn't change the injectors. When it starts in test mode then stops I smell raw fuel, doesn't have cat's either. Come to think of it, I don't notice a fuel smell when in normal operation and I just crank away. So maybe it's a fuel thing. Need to put a gauge on it.

Also aftermarket exhaust, No EGR connection. EGR plated off and EGR transducer still connected.

If it's not fuel related I'll start the DIS troubleshooting and hope the wiring harness isn't crap.
 
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