Michigander

We have tried many various ideas to get this engine to fire.
The plugs have been replaced and the old ones did smell like gas.
The fuel pump does turn on when you put the key to accessories.
The fuel filter is fine.
I believe the fuel pressure was at 39 or somewhere around there.
Gas is getting to the motor and there is a spark but no fire.
We think it might be a sensor in the fueling department but not sure.
Anybody have prior experience or have any ideas to what the problem could be?

blackoutoffroad2wd

They make a pressure gauge that you plug into we're u spark plugs go to check pressure at the plugs. If there's not enough pressure they won't fire right. Maybe it'll work never hurts to check.

Michigander

Can you rent those out at AutoZone or something?

udderbrudder

I think he's referring to a compression tester. To do this accurately you need to remove all the spark plugs.
I'd verify spark and injector pulses first. You also need to verify fuel pressure. You can check for inj pulses with a NOID light. Unplug an injector and connect the light where the injector was connected. Crank the engine-light should flash. To check for spark : unplug an ign wire and connect a spark tester to it. You should see and hear the spark jumping agross the tester gap. If all is ok with fuel pressure, spark, inj pulses-then I'd check compression.

Mr.Bones

Would not be a bad idea to check Cam sensor and Crank sensor. If they are not reading each other it will not start.

udderbrudder

They don't read each other.

Mr.Bones

Hummm, i may be wrong on this. I had a 4.2 that had a problem like this. Went to the shop and they told me my Crank sensor was out, and if the crank and Cam sensor are not reading each other it will not fire.

udderbrudder

The two sensors do not read each other. If you have no crank pos. sensor signal you will not get injector pulses and no spark. With no cam sensor the engine will fire but will not control timing properly resulting in loss of power, poor fuel economy, and a Service Engine Soon light. Sensors produce a digital square wave signal and send it to the PCM. Nothing more, nothing less!

Good old Bill

I'll add to this confusion, I was under the opinion the crankshaft position sensor was for ignition and the camshaft position sensor was for fuel delivery. I agree, they don't read each other, they do their thing for the computor to perform its own thing.

Mr.Bones

Well good, this was about 9 years ago. I hope your issue is a simple fix and works out just fine in the end. Good luck with it, and once again i learn something new everyday. Thanks.