erratic no start not drivable

[FFR2000]

2000 3.0 6 speed 2wd. Will start and run over 20 min, Shut down and start, shut down again and no start. Not a cranking problem. Fuel 60lb and spark. Idle sometimes race to over 2000 in between shifts. Thinking of shot-gunning an IAC valve to it . I NEED HELP.

 

[franklin2]

You need to put a scanner on it. Even if the check engine light is not on, I would get something hooked up to it.

 

[FFR2000]

No codes when scanner is hooked up.

 

[franklin2]

I would not think the IAC would cause a no start. Possible start and then stall, but not a no start.

Next time it stalls and will not start, keep a can of ether with you. Shoot some down in the engine and see if it tries to run. You need to narrow this down to a fuel or spark problem. I know you have been doing some testing, but the engine is not running for some reason. If it has fuel and spark it should run, you are missing something. Spraying starting fluid down in the engine will also bypass the injectors. Even though you have fuel pressure they might not be firing.

 

[FFR2000]

Started right up and ran fine this morning. Let it run for 10 min then I turned it off. Then did a restart several times until a no start. Has fuel pres. and spark. Opened air filter gave a shot ether down the intake tube while cranking. No Start. Can the IAC valve be closed so much it wont let in enough air even with ether in the inlet tube?

 

[2011Supercab]

First guess would be a failing crankshaft position sensor, they don't always set a code.

 

[franklin2]

No start with ether means a spark problem. Crankshaft sensor would be a no spark and most likely no fuel either because the computer probably uses that to verify the engine is turning and when to fire the injectors. Surprising it does not give a code sometimes.

 

[nickname23]

Does the IAC valve have play? It shouldn't be easy to move at all nor should it be moved manually.
My bad IAC will rattle and move easily by barely touching it with your finger. You can try cleaning it but eventually will need a new one.

Also check the Crankshaft Position Sensor wiring there could be a frayed wire. Or it could be a bad sensor because of contamination.

A bad IAC can definitely cause a no-start situation if it's not opening properly, if that happens you could start the engine by pressing the pedal but the computer won't be able to do the same because the IAC is going out.

If it has trouble starting try tapping the IAC with a rubber deadblow gently, if that's part of the problem and it's not completely broken it will eventually free the valve after a few knocks keeping the engine running.