I need someones help.

My '89 F150 300 2wd w/dual gas tanks has a fuel pump relay
that continues to run well after I shut off the engine. I
have replaced it several times but the problem keeps coming
back.Since I have 2 gas tanks, do I have 2 relays? What fixes
this problem.
Thanks

Phil

 

I'm looking at an 88 manual so maybe it's the same for an
89. There is only one fuel pump relay. The diagram shows
four wires going to the relay. The primary of the relay
are a red wire which is 12 volts supplied by the EEC. The
EEC energizes the relay by grounding a TLG colored wire
(Tan/Light green?)? or tan light gray?) This closes the
relay secondary contacts, yellow wire which is 12 volts
from the ignition switch. With the relay closed 12 volts
from the pink/black wire now provides the 12 volts to the
main fuel pump and the pump in the tank.

When you first turn the ignition on (don't start the
engine. The fuel pump should stay on for about 1 second
then go off. Does your's do that? It's all controlled
by the EEC.

According to the manual, the EEC module senses engine
speed and shuts off the fuel pump by opening the ground
circuit to the fuel pump relay when the engine stops
or is below 120 rpm. When you shut the engine off
if the fuel pump is still running unplug the
fuel pump relay. The fuel pump should stop. If it does,
I'd say the computer is bad.

 

I have an 88 E-150 with the 4.9L. The previous owner of my van must have had a problem with this relay circuit. Someone has by passed the relay circuit and hard wired 12V to the pump when the key is on. There seems to be now problem with this circuit jumper.