fuel pump not working...help!!!

[gill41083]

i have an 87 ranger 2wd with a 2.9, the fuel pump relay is not turning on, i have 12 volts at the yellow,red,and tan wires on the relay, if i jump the tan wire to ground it the pump runs constant but the truck will not start up like this, if i spray starting fluid in the intake it will fire up but dies when the starting fluid is burned out, i have been searching on here all day trying to trouble shoot this!!! Any one have any ideas what might be wrong?? Im thinking its the computer but wanted to get a second opinion before i go to the wrecking yard

 

[gill41083]

I did a little more investigating and i dont think the fuel pump up front on the frame rail is turning on, how could i test it? both pumps are new. thanks in advance for any little bit of help any one can give

 

[baddis]

ground the wire like you have already done. then check for power at the pump on the frame rail. i had to do this on my 88 and run new wires from the relay to the pumps

 

[gill41083]

so i have decided the front pump is bad, but would that make my relay not turn on?

 

[baddis]

iirc the relay runs both pumps. there are two wires and if i remember right they are tan coming out of the same connecter of the relay. did you have power at the frame rail pump?

 

[gill41083]

yes i have power at the frame rail pump when i ground the tan wire, the main problem im trying to figure out now is why the tan wire doesnt switch from 12 volts positive to a ground to turn on the relay. from what i have gathered from other post the tan wire is supposed to change polarity, right?

and thanks for the help so far.

 

[baddis]

i am not sure on that . i will check mine tomorrow if i have time unless someone else posts a reply quicker

 

[kena]

When you ground the Tan wire, you are manually energizing the fuel pump relay. The computer should be providing that ground through pin 22.

 

[gill41083]

ok thanks, i will check it when i get the new front pump. where is pin 22? i have a book to look at the wiring diagram, and how could i test to make sure it is working the way it should?

 

[baddis]

the plug is numbered on the computer