Well today my truck started up just fine and I drove it for about thirty minutes and parked it so that I could get some lunch. When I came back out to start the truck it would not turn over at all. I just replaced the fuel filter about one month ago and I check it again today and it is not stopped up. I turned the key to the on position and stuck my head under the fuel tank and I could not hear the fuel pump at all. I checked the ASD and Fuel relay in accordance with the Haynes manual and both relays checked good along with the relay box. My next step is to see if I can pull the wiring harness off the top of the fuel pump and measure the voltage when the key is turned on. Does anyone know what voltage I should read at the plug and is there anything else that I can do because I would hate to R&R the fuel pump and not have it solve my problem. Any help is greatly appreciated and thanks in advance.

 

I just thought of something... Is the fuel pump in the fuel tank, or is that just the fuel sending unit?

 

If the truck you are talking about is the one in your sig. you have a mechanical lift pump on the side of the engine and all the tank is is the sending unit. There is a good possibility that the shut off sol. or relay has gone bad. Ths shut off sol. is on the drivers side attatched to the rear of the injection pump and is attatched to a lever that should lift up when you try to start the engine.

 

Ok I will check the lift pump out. Now when you turn the key on you should be able to hear the sending unit in the fuel tank hum right?

 

No! No electronic pump on yours at all! There is an old fashioned mechanical lift pump on the side of the block ( like mentioned earlier ). More than likely your fuel shut off solenoid has either dies or lost power. On the back of the injection pump, there is a large golden colored solenoid ( usually gold colored ) turn the key on and then get under the hood and lift up on the rod that comes thru the rubber boot on the bottom end of the solenoid. If it comes up and stays up....the truck should start. If not you need to check for power and ground at the solenoid and go from there.

 

Ok I will go check out the fuel Solenoid. Now in my truck when everything is working properly does fuel start flowing into the fuel filter as soon as you turn the truck on or does it start flowing when you crank the engine?

 

Mechanical pumps pump fuel as soon as you start cranking. However, I've never had a diesel with a mech. pump. All of the old Chevy 350's worked that way.

 

Lift pump runs off the cam. Cams not turning, neither is the lift pump.

You said the truck "will not turn over at all"

Do you mean if will not fire or will not turn over?

 

Ok so I checked the fuel filter and blew through it and it was fine. I pulled out the ASD relay and checked it with an Ohm meter and it checked good. Checked the fuel shutdown solenoid and it checked out good. I reseated fuse number nine, the connection on the fuel heater relay, and the fuel shut-off solenoid relay. I cracked the bleeder bolt on top of the fuel filter and then I primed it until clean diesel come out and closed the bleeder bolt. Tried cranking the engine again, put the throttle at wide open and finally turned over ran really rough for about five seconds and then ran fine all the way home. Turned the truck off and started it again three more times with no problems. Any ideas on what might have happened?

 

You picked up air somehow. Fuel filter could have loosened, Fuel heater element could be leaking, fuel lines etc.

 

Solenoid shut off because of an electrical problem? Seen that happen before too. Look for corroded wires at the pos battery terminal on the drivers side battery. That is where the hold in relay gets it's power I believe.