Idling issues
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Idling issues
1986 F150 5.0 EFI. Truck was running ok, started surging then stalling and has a miss at idle higher rpm ok. This was happening intermittently and then tank pump quit. Replaced tank and rail pump now it runs again with original problem. Used a can of ether looking for vacuum leaks, nothing. Replace cap rotor wires and plugs. Blocked egr.
Any ideas??
Any ideas??
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From: Virginia
You need to clean the throttle body butterflies and the IAC (idle air control) valve. Take the IAC off and clean it with brake cleaner or something like that. You will find a bunch of oily soot in these components usually. Once you clean it up, drive it for a couple of days, the computer needs to relearn when changes are made.
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You need to clean the throttle body butterflies and the IAC (idle air control) valve. Take the IAC off and clean it with brake cleaner or something like that. You will find a bunch of oily soot in these components usually. Once you clean it up, drive it for a couple of days, the computer needs to relearn when changes are made.
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Pulled it off, everything was clean. Fuel pumps do not turn off, changed PCM relay and fuel relay, stopped surging still has miss. Hear some kind of clicking coming from back of engine, sounds like a really loud relay not a lifter or mechanical noise.
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From: Virginia
Find sparkplug wire #7 and #8. They will be the two at the rear driver's side. Move #7 wire as far away as you can from #8. It looks better and is natural to run them side by side since they are beside each other in the engine, but the firing order has them in sequence one after the other, and they can have a tendency to cross-fire and cause a miss. I think there is a TSB out on this. That might be what the noise is, the spark jumping from one wire to the other. Try it and see if it helps the miss.
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From: Angier, NC
I would say if the wires are cross firing and you can hear it they are bad in my book.
Another test is take a spray water bottle and at night spray the wires and see if you get a light show.
If so replace the wires with a well known brand.
Dave ----
Another test is take a spray water bottle and at night spray the wires and see if you get a light show.
If so replace the wires with a well known brand.
Dave ----
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Find sparkplug wire #7 and #8. They will be the two at the rear driver's side. Move #7 wire as far away as you can from #8. It looks better and is natural to run them side by side since they are beside each other in the engine, but the firing order has them in sequence one after the other, and they can have a tendency to cross-fire and cause a miss. I think there is a TSB out on this. That might be what the noise is, the spark jumping from one wire to the other. Try it and see if it helps the miss.
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FTE Legend
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From: Angier, NC
What if you turn the key a little bit motor to off or ACC what happens to the pumps?
I am thinking the IGN switch down on the top side of the steering column might be out of adjustment.
IIRC you set key to off, loosen the 2 screws holding the switch and use a wire pin to center the switch and then tighten the 2 screws.
If you pull the relay and they shut down if you plug the relay back in what happens?
Dave ----
I am thinking the IGN switch down on the top side of the steering column might be out of adjustment.
IIRC you set key to off, loosen the 2 screws holding the switch and use a wire pin to center the switch and then tighten the 2 screws.
If you pull the relay and they shut down if you plug the relay back in what happens?
Dave ----
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What if you turn the key a little bit motor to off or ACC what happens to the pumps?
I am thinking the IGN switch down on the top side of the steering column might be out of adjustment.
IIRC you set key to off, loosen the 2 screws holding the switch and use a wire pin to center the switch and then tighten the 2 screws.
If you pull the relay and they shut down if you plug the relay back in what happens?
Dave ----
I am thinking the IGN switch down on the top side of the steering column might be out of adjustment.
IIRC you set key to off, loosen the 2 screws holding the switch and use a wire pin to center the switch and then tighten the 2 screws.
If you pull the relay and they shut down if you plug the relay back in what happens?
Dave ----
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