Hello group. I am a new member here with a problem regarding no juice going into the fuel pumps on my F-250 5.8 4x4. I was hoping someone could assist me in figuring out what could be wrong.

There is no electrical power reaching either of the two internal fuel pumps which are in the gas tank.

We replaced the fuel pump relay, and the 20 amp fuse.

The inertia switch was not tripped and is in the normal operating position.

When we parked this truck one year ago, it ran good. It still turns over good but it will not start. I replaced the distributor and rotor. I also used a spark plug tester and it is getting a spark when we crank it over.

We bought a fuel pump but did not want to install it until we fixed the electrical problem. Today, I took off the utility bed and whenever we find the fuel pump problem, we'll take off both tanks, clean them, install pumps and fuel filter, and end up putting on a regular truck bed.

Also, there is no power to the inertia switch.

We don't know much about electronics on vehicles so any ideas to our problems would be greatly appreciated. All I know is that the engine light remains on.

Thanks.

 

welcome to FTE.
what year truck?
not sure on the newer ones, but on the pre 89 trucks the fuel pomp relay gets it's power from the eec relay.
these older trucks were problems with the relay contacts corroding and loosing power to the relay.

i had one that the only way to make it run was to rewire the fuel pump circuit.
that was 3 years ago and it is still purring like a swiss army knife.

 

Thxs Tom. I have a '95. Still puzzled by this whole thing.

 

More than once it turned out to be a bad relay socket. Check power is getting to the Fuel Pump relay.

Here is a diagram from oldfuelinjection.com

 

Agree with above post . As stated the truck sat for a year . the contacts could be corroded . I would also ck for rodent damage . The little buggers have a habit of chewing on wires . I have seen lots of issues because of rodent damage . Just a thought !

 

Note that on these trucks there is only power to the fuel pumps for one second when you turn on the key. If you are just turning on the the key and then checking for power there will be none.

I dough that you have a problem with the relays on a 1995 but if you want to check. See if the horn works and then see if the marker lamps work and if they do just swap the horn relay and the marker relay with the PCM Power relay and the Fuel Pump relay.

To check the fuel pump circuit ground pin #6 of the EEC Self-Test plug and turn on the key. This will bypass the PCM computer. Use a test light that will put a load on the circuit and not a meter that will not. A meter will show power when it is not there.




The photo below is checking for a complete ground through the PCM Computer while testing the fuel pumps:


The location of the relays:


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I took for granted that he knew power was only for a brief time at key on . ASSUME .! Well , hope the above post helps !