ok hears the deal my 2001 5.4 f250 was acting strange drove to store fine come out wont start just cranks...
no fuel pressure at rail . checked fuses all good.
pulled relay all seem good
ok no power to pump no power at inerta (sp) switch my question is where will the power to that swintch on pass side come from
are there more fuel pump relays. tried to power pump at pump with battery and no luck.
before i spend 175 on pump i have to figuer why no power or am i over thinking this?
thanks

 

Welcome to the site..

If you have no power at the inertia, try running a test lead there and see if the pump will run. Make sure the switch is closed. It should if there isn't any power there. The pump feed comes from the fuel relay. Could be that the relay is bad and we can look there next, and the fuel pump power distribution throughout in case something was missed. But since you want/need to prove the pump out, run a test lead to the inertia first. With the lead installed, check the connector at the tank and see if you pick up the voltage there as well..

 

i tried power at pump didnt work . am i missing a relay under the dash.i need to figure why no power from fuse to inerta switch?

 

Are you certain you were on the correct circuit at the pump harness?

I could see the pump not running due to no power input, but no power to the inertia AND the pump failed.. Highly unlikely. If there's no power 'through' the inertia, adding it at the fuel module harness connector should spin the pump. Could possibly be a failing pump, but then you should still see voltage through the inertia and at the pump harness connector.

The power to the pump runs directly off the closed inertia.. PCM is in charge of the grounding at the fuel pump relay for pump run time. If you pull the fuel pump relay, you should have 2 of the connector terminals there that carry a voltage. 1 will be 'hot all the time' and the other 'switched' on with the key cycled ON. If the fuses are good both these should be active. The other terminals (2) at the relay connector will be ouput to the inertia, and the ground/PCM control of the relay.

Since you have no power at the inertia, it points towards the relay, circuits/wire, or 'possibly' the PCM.. But,, adding voltage or 'bridging' the fuel relay connector (to the inertia side of the relay connector and 'hot all the time' input), or adding voltage just at inertia will have the same affect. Same with adding voltage at the fuel module connector,, should start the truck unless the pump quit... Adding power at those points will take the PCM out of the diagnostics.. More so if everything else proves out..

 

i guess my question is where is the fuel pump relay located? under the dash?
i suck at electrical issues but i can get this in time..

 

ok well here is the latest its been in side warm shop . i was messing with the pcmm and it started but did not restart. so its pcm or wire bad

 

...or meb'be a loose or poorly coonected plug?

 

ok i got it the relay under the dash was bad put new relay in shes a runner