help troubleshootinf pickup, 91 f150 6cyl

[dirtyoldman]

Speed density injection systems need an RPM input butt I can't remember where they get it.

[dirtyoldman]

I don't think the pump is your problem, but it would be helpful if you could check fuel pressure. I think the port is on the back of the fuel rail, looks like a tire valve.

[Tig]

How old is the fuel?

[LD1]

Not sure on the 91's, but the 89's had THREE fuel pumps. One in each tank and ONE on the frame rail under the drivers side floorboard. So thats worth a look there.

As to the pump switching off, When just cycling the key, yes I think it switches off after a few seconds. Now I dont know if that is on a timer or a pressure switch, but i think it is a timer cause even if you cycle real fast it always seems to run the exact same amount. But I dont know for sure.

[kc5dlo]

How old is the fuel?

1+ on that

[Dana Warner]

Any possibility of a vacuum leak on a hose that an animal may have chewed?

[SPIKER]

Hey Guys:

Pulled the truck inside (raining for 4 or 5 days straight now) but had forgotten the fuel pressure tester kit in trunk of womans car so no go on the testing today.

The gas is older but should be fine. cleaned & re-gapped the plugs all seemed good (except one I broke getting it out.)

I had pulled & repaired the wiper switch prior to moving it to where it was parked when it failed to start. One of the things I'm going to look at is to be sure I didn't knock something loose under dash or behind switch as it sets right above fuse panel.

took about 5 tries of re-firing it to get it to move enough to go into barn.

The 1990 was 1st with in-tank HP pumps not the older low pressure in-tank pumps and external high pressure pump.

I am worried there could be a chew mark or wire somewhere as the spot I parked it was higher grass...

tomorrow I'll be stopping out to hopefully dry truck to work on it.

Mark

[deerefan]

Hey Guys:

Pulled the truck inside (raining for 4 or 5 days straight now) but had forgotten the fuel pressure tester kit in trunk of womans car so no go on the testing today.

The gas is older but should be fine. cleaned & re-gapped the plugs all seemed good (except one I broke getting it out.)

I had pulled & repaired the wiper switch prior to moving it to where it was parked when it failed to start. One of the things I'm going to look at is to be sure I didn't knock something loose under dash or behind switch as it sets right above fuse panel.

took about 5 tries of re-firing it to get it to move enough to go into barn.

The 1990 was 1st with in-tank HP pumps not the older low pressure in-tank pumps and external high pressure pump.

I am worried there could be a chew mark or wire somewhere as the spot I parked it was higher grass...

tomorrow I'll be stopping out to hopefully dry truck to work on it.

Mark

Check your throttle body for excessive carbon buildup. Also, if your truck has one, check the throttle position sensor. Any codes?

[SPIKER]

Deerfan: the check engine light is on now, it showed up on the last time it was running on way home. My code reader is messed up so not sure what is up with it (or the ECM) I'm waiting for SANDY to get out of the way so I can get back working on it. I'll hook up y analog meter and try testing it that way to see what code it has up.

throttle body was clean, had intake ducting off when I cleaned plugs

Mark

[SPIKER]

Hey Guys: did a bit of work on it today,
Fuel Pressure is perfect with a NEW Pressure Regulator (was probably fine prior but did not put OLD one back On)

Pressure held for a good time like it should. Ran pumps independently of each other and both were same/good pressure. One of the pumps sounds a bit worse than the other but functioning.

I pulled ECM (Power systems modal) and confirmed pumps did not run and check eng light went of. Tried to jumper test the modal for codes but it will not respond to testing procedure and would not test with the FORD specific OBD1 tester I have. The Engine will RUN if a shot of ether is used to start the engine. it however has little or no power. I'm now thinking maybe the ECM may be bad? I THINK the fuel injectors fire in 2 sets 3 & 3 at same time so maybe only 1/2 of them are firing???

Next testing will be on the Injectors to see if any of them are ON/OFF the right way or not... Anyone know best/easiest way to test them?

How about the fuel Pumps no one answered if they are supposed to only start and stop when Pressure is UP.? As they run NOW they stay running when the KEY is on and STAY ON as long as the KEY is on...

thanks
Mark