SC wont start sometimes

ebodycab

Registered User
My 89SC doesn't start sometimes when its hot...have to crank it 2-3 times then it starts...it does this once in a blue moon..usually starts right away when hot or cold..what could be the problem???
 
What does it sound like when it's cranking. Like it's trying to start, or like it's totally dead?

The cam sensor failure can cause an intermittant start behavior and the engine will not act like it's trying to start. See this thread for an explination of that possibility:
Inconsistant Starting

You should try and pull codes as well.
 
when its acting up,engine just cranks over,does not want to start at all,then after 2-3 times starts..where is the cam sensor? thanks...
 
The sensor is mounted where you might expect a distributor, down on the front of the engine front cover, just to the rear of the top left of the water pump. It's a black round object.

Make sure that when you try to get it started that after each try you turn the ignition key off, then back on to try again. This is what randomizes the EEC's attempt for starting. The CAM sensor is used for fuel injector timing mostly, but for starting it tells the DIS system when cylinder 1 is at top dead center as well. After that most spark info comes from the crankshaft sensor.

Since it seems to be heat related, I'd start diagnosis by simply disconnecting connections under the engine compartment checking for corrosion, cleaning them up, and then reconnecting. I'd also suggest picking up some thermal heat sink compound from a store that sells it (computer stores, radio shack) and pull the DIS module up, clean off the bottom of it and it's mount, and then put fresh heat sink compound below it before tightening it down.

The DIS can also play a role in a hot engine no start condition as it's a part that generates a lot of heat itself. It uses the bracket it's mounted to as a big heat sink, and if the compound under neath it is gone, it may not be getting rid of enough heat.

One other think on the CAM sensor. If that's the problem, your engine will start after a just a few cycles of on/start/off, on/start/off. This because the DIS guesses. If it takes more than just a few retries to get it to start, it's not likely the CAM sensor and could be something else. Watch your upshift light(assuming an automatic) when cranking. If you see your upshift light on during cranking, that's a sign of no Crank Position Sensor, and that will prevent engine start completely.
 
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