Won't Start

LoneStarSC

Registered User
I have sifted through the forums, and I have found many similar problems, but none exactly. I just bought a 1990 SC with 54K. It started and ran perfectly. I ran it up to operating temp on a test drive, then I went to restart it about 15min later and it would only crank. I bought the car anyway, based on it's immaculate condition and good price. I figured that it would be a simple electrical problem, perhaps a Crank Sensor? What do you think?
 
There are a lot of things it could be. Does the upshift light stay on while cranking? If it does, that would be a sign of a bad crank sensor. Try unplugging the cam sensor and see if it will start like that. You can try a fuel pressure test too. Those are just a few things you can try. You may also want to check the heatsink for the DIS. If it's dried up, that could cause cranking problems too.

edit: also check ground wires. if you have a scanner, you can do a KOEO test.
 
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Cam sensor

I have read many posts that say "disconnect the cam sensor" to eliminate it as a problem. Why/how does this work? Would the car start with the cam sensor disconnected?
 
The EEC-IV has a failure mode with the cam sensor that will allow the car to start with it disabled. If the Crank Sensor is out, the engine can not start.

If you disconnect the cam sensor, you need to do a process of key on, crank, key off. Key on, crank, key off. You should run this cycle 5 times. During each of these times the EEC will "guess" at which cylinder it should fuel and try to start. If it never starts, then the problem isn't primarily the Cam sensor. (The cam sensor could be a secondary failure, but by not starting with it disconnected, you know that it isn't the main reason why the engine won't start)

Most no-start conditions really should be approached for the first thing of verifying fuel pressure. Make sure your fuel pump is working.

Once you verify fuel pressure, then check all the wiring connections. To the DIS, to the Crank Sensor, to the Cam Sensor, to the Coil Pack.

Below is a link to the DIS no start pinpoint tests from my former 89 tbird. Should be the same as the 90.
http://mnharms.com/tutorials/disnostart/

Make sure you check for any stored codes as well.
 
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Thanks,

That flowchart is awesome. I won't get a chance to work with the car for another week, but that should help.
 
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