Crank no fire

[UglyDuck]

Just completed engine overhaul. Engine cranks but doesn’t fire. Has fuel pressure. New crank sensor. New Ignition coil. Old cam sensor (waiting for new one). Cam position timing correctly to engine.

Can a bad cam sensor cause no spark?

 

[Jerry Bransford]

See if the tachometer is rising up any at all while the engine is being cranked. If the tach needle stays put at the bottom while the engine is being cranked it's likely a bad crankshaft position sensor.

 

[UglyDuck]

See if the tachometer is rising up any at all while the engine is being cranked. If the tach needle stays put at the bottom while the engine is being cranked it's likely a bad crankshaft position sensor.

No movement on the tach at all. Not even when the key is turned on initially. Nothing while cranking either. Brand new crank position sensor installed last night.

 

[JPHikr]

Spray Starter fluid in intake if it fires you have a fuel problem, if not an ignition problem.

 

[UglyDuck]

It’s ignition. No spark

 

[JKP]

Since the coil rail Jeeps are waste spark systems, both cyls at TDC are fired every time even though only 1 is on the power stroke. Firing is based on the crank sensor.

The cam sensor is used to fire the fuel injectors sequentially.

I know on the 05 and 06 it will run with a bad cam sensor as the PCM defaults to a batch firing of the injectors, but it will be a long crank to start.

I seem to recall that some of the older ones will not run with a bad cam sensor, but I don't know if it's from lack of spark or lack of fuel injector pulsing.

 

[UglyDuck]

Since the coil rail Jeeps are waste spark systems, both cyls at TDC are fired every time even though only 1 is on the power stroke. Firing is based on the crank sensor.

The cam sensor is used to fire the fuel injectors sequentially.

I know on the 05 and 06 it will run with a bad cam sensor as the PCM defaults to a batch firing of the injectors, but it will be a long crank to start.

I seem to recall that some of the older ones will not run with a bad cam sensor, but I don't know if it's from lack of spark or lack of fuel injector pulsing.

I’m highly suspicious of the cam sensor. Might run out an buy a parts store one even though I have one on order that supposed to arrive tomorrow

 

[UglyDuck]

Problem found to be the crank sensor wiring circuit on the harness. Used the factory diagnostic troubleshooting guide that’s posted in the resource sticky thread to run down the issue.