fuel pump dont stop priming

[otto87]

my problem all stated when fuel pum would randomly shut of while driving found problem to be bad connections when i fixed those i accidentally unplugged computer ground wire so fuel pump wouldnt come on at all i replaced the fuel pump relay but it didnt help when i found the loose ground i hooked it up but now fuel pump dosnt shut off after 3-5 secslike its supposed to one of the connectors to the fuel pump broke so as a temd fix i used a smaller gage wire to connect my hot to fuel pump could that be the problem truck cranks and idles rough and rich but wont get over 35 in any gear need help pls

 

[Andy D]

put the old relay back in and see what happens. Just because a relay fits into the socket doesnt mean it is the right one.

 

[adsm08]

Get the original relay in, recheck it, and then if it is still not running right double check all your wiring repairs.

 

[otto87]

fuel pump not shutting off when primed

i put the old relay back in and same thing rechecked all my wire connections and when i drove it it idles rich and sounds like its got a cam but it dosnt im stumpped

 

[RonD]

The fuel pump relay supplies power to the pump when it is Grounded, that's how the PCM(computer) operates it, to turn on the fuel pump the PCM grounds the relay causing it to close which sends power to the pump.

The relay has 2 separate 12volt INs, one for powering the fuel pump(30 amp fuse) and one from key being on(general power wires).

If you remove the relay you can test this on the socket for the relay.

There are two other connections, one is to pass power to the inertia switch and then to the pump.
The other is the Ground operated the PCM, so this should only be a ground when PCM turns on the pump, 1 or 2 seconds then no ground
Test this using either of the 12volts with a test light, if it is a ground all the time then either the PCM is the problem or that PCM wire is shorted to ground, so relay and pump is on all the time.
Wiggle the wires around and inspect the wires where they pass thru the firewall.

Since you are having all these wiring issues was there some kind of damage to the wiring, heat, accident, ....??


What engine do you have?

 

[otto87]

just been used

im not really sure fiancees dad bought it in 89 its been to alaska and back twice and it used to sit on rde share lots alot when he was an over the road truck driver. to me though i think i need to have the whole tuck rewired but i want to do an engine swap for the 2.9 it has now to either a 289 or 302.taking advice on that too. but thats future stuff right now i need it to get back and frth to work so i need to figure problem out soon. does the pcm ground go to frame.

 

[shane96ranger]

Did you figure out if the trigger (from the PCM) is constant? That would be the first thing I checked.