From the beginning, went to start truck one day and it it would'nt start just turn over and over. Replaced catalytic converter and muffler, o2 sensors,cam shaft sensor ,coil ect.... I replaced the fuel pump last weekend , it started up drove about 2 miles then died and would'nt start back up. Some days it would start drive a few miles act like it was out of gas then die then after it sat for awhile it would start back up and rinse repeat. Anyone have any advise or had a truck do this? I would greatly appreciate any help. Also my oil pressure reading dropped to 0.

 

Is teh CEL on? If not get a scanner and scan for stored codes... What year and what engine?

 

Crank sensor.

 

1997 5.9 cel was not on

 

crank sensor is a good guess.

but the main question is - do you have a fuel problem or a spark/timing problem.
check fuel pressure at the rail, should be 49 psi, +/- 5
also - if it cranks on starting fluid of a SAFE splash of gas, then it points to spark.

be aware the ASD system shuts down fuel pump and coil if there's no signal from crank position sensor that the engine is running. but - fuel pump should come on for about 5 seconds at ignition on to prime/pressurize the fuel system.

spark should stay on longer, but i'm not sure how long. check it with an old plug in the spark plug boot.

 

the coil is no good. its getting hot and not firing once it cools down it fires. normally the crank sensor and cam sensors will just quit out. and will always throw a code. the coil will never throw a code and will act like your running out of gas. also the ASD which everone dreads it normally just the relay that goes bad. its there to shut the car down in case os and accident thats all. im going to bet its the coil!

 

Definitely test for spark at the coil. I would agree that it's the Crank sensor. Since my motor swap, I've learned a lot about the 5.9. If you're not getting spark, check that its getting 12v with the key in the run position. You can test the coil by doing a resistance check. Check between the output and the input sides, should be around 12k ohm (I think). If its good, definitely check the crank sensor. You can use an oscilloscope to check that its sending signal while you go to crank it, or just go out and buy a new one, they run about $50 to $100 depending on if its an auto or manual.

 

It was the crankshaft sensor I replaced not the camshaft ,sorry bout that. The sensor on the back of the motor hard to get to .

 

cam position sensor (aka secondary pickup coil) which lives under the distributor cap can also mess with timing, spark, and fuel sync.

its also hard to reach.

 

could the comp have gone bad?