Engine fails when warm

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Jan 3, 2004 | 09:36 PM

Altonjh

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Engine fails when warm

This is my first post. My 1992 F-150 with 302, automatic transmission, starts and drives great for about 5 miles. Then, it suddenly acts like a fellow that has been socked in the stomach. There is nothing gradual about this; it happens suddenly, leaving me with almost no power at all. After the truck is shut down for a while, it will restart and run great again. I have partially rodded out the catalytic converter, changed the fuel filter, ignition module, plugs, oxygen senser, throttle position senser, ignition coil, distributor coil, fuel pressure regulator, MAP senser. I pulled the codes, but nothing helped me there. It does smoke when it bogs down and smells peculiar. It appears something is failing when brought up to a higher temperature. Also, when this truck breaks down on the road, I can unplug the MAP senser (the new one) and it will run up to 45 mph just to get me home. I do not think the new MAP is bad, because the old MAP senser did the same way.

Does this truck have a crankshaft position sensor. I cannot seem to see one one it?

If anyone has any ideas, I would sure welcome them.

Jan 4, 2004 | 11:10 AM

circledirt

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Joined: Aug 2003

Posts: 122

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From: kansas

Just a guess. Does your truck have a egr feedback sensor, or a position senser on top of the egr valve? I've seen either one of these short internally, and pull the 5 volt reference coming out of the ecm to nothing, therfore screwing up all the other sensor readings. No crank sensor, its all in the hall effect sensor inside dist.

Jan 4, 2004 | 01:11 PM

Altonjh

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I will find out if it does. Thanks for the idea.

Jan 5, 2004 | 10:50 AM

bdonalds

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Joined: Jan 2001

Posts: 110

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From: Central Illinois

When it smokes, what color is it? Can you describe the peculiar smell?

Does the check engine light come on when it happens?

Jan 5, 2004 | 12:44 PM

rainbowATF

Senior User

Joined: Oct 2003

Posts: 480

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From: Elyria, Ohio

No hot run

Don't know if this will help. I had similar problem with pass car (not Ford); however car would not run when hot; but I discovered that if I unplug the MAF I could get the car to run and accelerate. Apparently unplugging it threw the computer into default value run mode and would compensate for my real problem. I eventually traced my problem to low fuel pressure of 10 psi and had to drop tank and replace elec pump to bring up to 40-45. In mean time I replaced MAF, TPS, Injectors, wires, plugs etc, etc with no improvement, alot work and money.

Jan 5, 2004 | 12:49 PM

stepman

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Joined: Dec 2002

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From: peoria, az

I think the smell would probably be like sulfer. Usually a bad O2 sensor but, I too would check the fuel pressure.

Jan 5, 2004 | 04:40 PM

Altonjh

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I changed the egr position sensor today and drove the truck about 18 miles with no problems. I will go further tomorrow and let you know. The most recent trip last week took me about 3 miles before it failed. But, it was only 50 degrees outside today.

When it had failed before, the smoke appeared to be very black; I am sure it was raw gasoline. If you let it keep running, it would gas-burn the spark-plugs. As far as odor, it burned the nose like sulphur and gasoline. Whenever the engine would fail, I have tried switching to another fuel tank, so I ruled out a weak pump unless this truck has a common pump somewhere. I have changed the filter located amidships on the chassis.

I really appreciate all of the help and l will let you know how the truck does.