Fuel Pump

When Driving or just sometimes trying to start the engine, there is a loss of power to the fuel pump relay coil.

What would cause a situation where the Engine Control Unit
(Computer) to not send the signal to the relay?

Sometimes the engine will start shortly after going dead, more often than not it wont. I have manually thrown the coil switch to start the engine and currently, the engine is starting normally.

Just do not want to have it shut down again while driving.
Is there a sensor that could be causing this?

We have already determined that the computer is not sending a pulse to the relay. We are thinking that it is a weak or worn Crankshaft Position Sensor.

Ok so let's say I was stupid and fried my pcm. Then why would my truck run off an external fuel source after I tried all the other stuff.

Not sensor because spark would not be present. What we did was removed the relay and used a jumper wire from the 15 amp fuse used by the fuel pump and jumped it to the relay. In that way, only when the ignition is on will the fuel pump work. Crappy way of doing things, but better than having the car shut down as you drive down the freeway with no steering, etc. The problem was sporadic and I just didn't trust it anymore. Probably was the computer..?

Car doesn't start on first attemp. Engine is turning over, but it won't start. I turn the key to off and retry. It starts on second attemp. Is the fuel pump relay going out and needs replacing?
Thanks
Kevin

Sometimes it will not start and other times it starts right up and runs perfectly. Whenever it doesn't start, it cranks over like crazy, however it reads no fuel pressure at the rail. When it does start, it reads plenty of fuel pressure. The battery and connections have been cleaned thoroughly, the fuel filter and fuel pump both have been replaced. Also, the fuel pump relay has been replaced.

Could this be an electrical issue? Anyone have an idea of what it could be? I have heard that it could be the actual fuse box itself, but I'm not sure if that would fix it or not. I have inspected the circuit board inside of the fuse box and it does not seem to be burned anywhere, but I'm not sure.

Can someone please help?

Thanks in advance!

Also, by the way, I have checked and it is not giving any codes either.

And, this might be just coincidence, but it seems that when it does this that if I bang on the fuse box with the bottom of my fist 2-3 times; then it will start. I'm not sure if that has anything to do with it or not.

Thanks for the answer. Actually, it was the PCM relay that was replaced as I am told that the fuel pump relay is built into the circuit board of the fuse box. I have noticed that the PCM relay seems to get pretty hot. Do I need to pull the PCM relay back out and apply dielectric grease on the prongs of that one? Is that the one you're talking about or should I apply it to all of them?

Ok. So, those are the classic symptoms of the fuel pump relay failing or starting to fail? Then it is not sending power to the fuel pump sometimes and sometimes it does? Then, that would explain why when it is just cranking and not starting, that I read no fuel pressure at all on the rail. Do the dealer mechanics replace the relays? I live in rural Northeast Georgia and am not sure of a mechanic to check with about this.