1993 f 150 5.8l fuel delivery problem
07-27-2016, 04:02 PM
#1
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1993 f 150 5.8l fuel delivery problem
Good afternoon all.. Looking for help on 93 f 150 xlt long bed xtra cab with 5.8l.
Can get truck to fire over with starter fluid. Cannot hear front or rear pumps run. Have replaced pumps with known good ones, still no pump.
Voltage across supply/return pins seems to be around 10.5 to 11v.
Could it be a grounding problem or possible ecm?
Tank switch works properly, cut off ok also.
Strange thing is we got truck to start initially with starter fluid.. stayed running.
Slammed hood, engine cut off and would still crank, but no run. will fire over with starter fluid, but never starts. Pumps never kick on that I can tell. seem to all ohm out good.
Have looked for bad connections, replaced fuses and relays, looked for all obvious issues, but this one has me stumped..
Any ideas or assistance diagrams etc would be greatly appreciated.
Thanks and have a great day..
Can get truck to fire over with starter fluid. Cannot hear front or rear pumps run. Have replaced pumps with known good ones, still no pump.
Voltage across supply/return pins seems to be around 10.5 to 11v.
Could it be a grounding problem or possible ecm?
Tank switch works properly, cut off ok also.
Strange thing is we got truck to start initially with starter fluid.. stayed running.
Slammed hood, engine cut off and would still crank, but no run. will fire over with starter fluid, but never starts. Pumps never kick on that I can tell. seem to all ohm out good.
Have looked for bad connections, replaced fuses and relays, looked for all obvious issues, but this one has me stumped..
Any ideas or assistance diagrams etc would be greatly appreciated.
Thanks and have a great day..
07-27-2016, 06:01 PM
#3
Power to the relay is controlled by the PCM. There's the prime -2 second signal - and the run signal. They both go through the relay. The run signal will not happen if the engine is not running (or at least turning, not sure which).
After the relay, the other things in the circuit are the dash switch (dual tanks) and the inertia switch (passenger kick panel) and then the pump.
Use a test light to ensure that power is getting to, and then through, each one of those.
Every time you turn the key off and then back to on, you should hear the pump prime.
May be worth putting a fuel pressure gauge on it if you do hear them.
If you can't hear them, there's a power issue or the pumps are no good.
Another place that occasionally causes the no power issue is the underside of the power distribution box where the wires come up to connect to the relay.
A test light should go a long way in narrowing things down.
After the relay, the other things in the circuit are the dash switch (dual tanks) and the inertia switch (passenger kick panel) and then the pump.
Use a test light to ensure that power is getting to, and then through, each one of those.
Every time you turn the key off and then back to on, you should hear the pump prime.
May be worth putting a fuel pressure gauge on it if you do hear them.
If you can't hear them, there's a power issue or the pumps are no good.
Another place that occasionally causes the no power issue is the underside of the power distribution box where the wires come up to connect to the relay.
A test light should go a long way in narrowing things down.
