I recently bought an F-350, 351, 5-Speed, single fuel tank. I bought it not running, took it home and have narrowed it down to no fuel. It has spark and will run on starting fluid. There is voltage on the wire to the fuel gage sender in the tank, but there is no voltage to the pump itself. The fuel pump relay has voltage. What is between the relay and the pump itself that I could check? What else can I check?

Thanks for any help, Keith

 

the ecm grounds the relay to make it put voltage to the pump if im not mistaken. BUT on that model i think there is 2 pumps. a low pressure feeder pump in the tank and the high pressure one on the frame rail.

 

Thanks wolfsmurf, there is a low pressure pump in the tank and a high pressure on the frame rail. Neither have power. How do I check the ECM ground or does that mean I need to replace the ECM?

Thanks, Keith

 

Ground pin #6 of the EEC self-test plug with the key on and see if the pumps run.



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check the ground wires at the core support/neg battery terminal also

 

Thanks a lot guys, but...

subford, I thinki I grounded the #6 pin correctly, but that didn't work. Can you describe exactly how I should ground it to make sure I did it correctly?

deeznut822, what exactly is the core support?

Thanks guys, haven't had much time to look at it, but if you can give me some more leads, I will have a look at it this evening.

Thanks again, Keith

 

You can short it to pin #2 or the any good ground (Neg post of battery or engine block).
You must also have the key on so the EEC Power relay is on (picked/made).

He was talking about the radiator core support on newer trucks.
On your 88 it would be the small black wire with a green stripe hooked to the NEG (-) post of the battery. This is the ground wire for the EEC Power relay and the EEC Computer.

Also check the Inertia switch, push down on the button on top. Location is in the bottom diagram.





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Thanks so much for helping me with this guys. I finally got the #6 pin grounded correctly and the pumps do indeed come on. What does this tell me? I'm excited to fix it, but don't know what to do now.

I checked the inertia switch straight away and the button was down, I always wondered in the back of my mind if that switch itself was bad internally..

Thanks again, Keith

 

Sounds like you may need a computer.
But make sure the small black wire with a green stripe has a good ground coming off the NEG (-) post of the battery.
Also check for power with the key on at pins 1, 37 & 57 of the computer as well as a ground at pins 40 & 60.
If that is all good then you need a EEC computer.

 

Well, I feel a bit stupid, but am happy to report that the truck is up and running.

When I bought it, it had been sitting for two years and didn't have a battery in it. I put a used battery in it and connected the two battery cables. I never even saw the smaller wire that was referred to by subford. I looked around and it was actually a double wire hanging down in the engine bay with bare ends that wasn't attached to anything. I connected it with the negative post of the battery (which it was cut to length for ;-) ) and the truck started right up.

Thanks for all your help guys. A few more very minor things to sort so may have more questions, at least now I know where to turn.

Thanks again, Keith