88rxn/a

Here's the issue:
The truck just stopped one day. It turns over but will not start. We jumped the fuel pump relay (relay 30 to 87) and got the pump to work. Once we jumped the pump we tried to fire the engine (turned the key to start) with no luck, it still just turns.
We checked all the fuses and relays related to the fuel pump and PCM. We found the power point fuse was blown and replaced it wit no luck. All relays were swapped from another running car under the hood (fuel pump relay and PCM relay). We also swapped out the other PCM relay under the dash with no luck.
As a last resort we checked one of the coils for 12 volts on the plug and it had none(turned the key to start). I do not know how to check anything else or the PCM to see if its bad? I am not sure what comes between the fuel pump relay and battery so i may diagnose. Could i have missed a fuse that keeps the PCM or fuel pump from working correctly that's not labeled PCM or fuel pump?

ANY help is appreciated!

*EDIT*
i forgot to mention, the PCM,cluster (relay 2) under the dash was warm to the touch? we swapped it out for another with no different results. and the inertia switch is good.

Frank_Ford

The fuel pump will come on for about 3 seconds when you turn on the key to pressurize the system. Thereafter, the fuel pump works with the engine turning over. If you are getting fuel to the fuel rail, it is not your fuel pump. I have been known to test this by having a buddy turn over the engine after I have removed a cap on the fuel rail and I watch for fuel to gush out. I always do this outside because I don't want to take a chance of burning down my garage. I also have a fire extinguisher standing by. I don't recommend doing this because it is dangerous but it is a fast way to determine if the fuel pump is working.

If not the fuel pump, check the crank sensor and the cam sensor. The crank sensor is most common problem. If the PCM does not receive a signal from the crank or cam sensor, it does not know where or when to send a spark to the plugs. As a result, it sends no spark at all. First check to see if you are getting spark when the engine is turned over. If no spark, check the crank sensor by taking out the 4 bolts to the A/C compressor and moving it to the side. Then take out 1 bolt to remove the crank sensor. Sometimes you can clean the sensor and connection and it will work again. A new sensor costs about $25. With the right tools you can test the sensor. The cam sensor is on the opposite side of the engine in the front by the cam shaft and is easy to remove and change.

Jbrew

Exactly, same as Frank suggests, - Crank or Cam, - usually the crank sensor, but I've seen the cam sensor do the same dang thing.

88rxn/a

thanks you two! the only way i can get power to the fuel pump is to "hot wire" the fuel relay for the fuel pump. even then, if i crank the motor with the fuel pump hot wired i cannot get it to fire.
we will check the crank sensor.
also, i remember seeing the check engine light while trying to start it. if i remember correctly i seen a thread stating this is an easy way to determine if the CPU is working or not.
once we get a chance to replace the crank sensor. i will report back.

88rxn/a

so we tried the crank sensor today and still no luck (installed a new one).
any other suggestions?
thanks

w0lvez

Did you check the Fuel pump Inertia Switch located at the passenger side kick panel? Can you smell fuel coming out from the tail pipe? If you always keep the fuel level low it will overheat the fuel pump.

88rxn/a

Yes, verified by using a light tester on both sides of it. Also, when I jumped the fuel pump under the hood it worked fine.

Carcrazygts2

The PCM controls the ground for the fuel pump. See if anyone you know that works in a auto shop has a high end scanner. Otherwise you may need to take it to the dealer. There is a code that is triggered when there is memory fault in the pcm. That code is p0600. If that code is cuurent or in history there is a issue with the pcm and it will cause a vehicle to just die.

w0lvez

Check the voltage on the Fuel Injector connector while cranking the engine.

88rxn/a

thanks, ill ask around but i don't think i know anyone with a high end scanner. i have a cheaper one i can get at work but that's about it.
i will check the injector for voltage wOlvez,
thanks!