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Jan 29, 2010 | 08:10 PM

radicalmechanical

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Suggestions? I'm stumped.

I have an 95 F150 with 4.9L EFI motor. About 2 months ago the truck started to buck and run poorly. We traced this down to bad fuel injectors. The truck ran beautifully for the last two months... then the other day the truck just shut off while idling... like it ran out of gas. Try to start it again and cranks but no start. Then I wait until the engine is cold again and the truck starts right up and runs perfectly until something heats up and shuts the truck off. When the truck is acting up I first checked fuel pressure ( this stuff is tell tail fuel pump issues).. I have tons of fuel pressure. I then checked for spark... bright blue spark... Then I checked for injector pulse... ding ding ding.. no injector pulse... Now I now there are lots of things that could tell the computer to shut off spark and injection pulse.. .but just no injection pulse.. very weird.
Things I've replaced within the last two months ... Engine Control Module, MAP sensor, Engine temperature sensor, fuel injectors, plug wires, plugs, coil, cap, rotor, battery, alternator... and a boat load of other unrelated brake and suspension parts.
If anyone has any clue what is telling the injectors not to fire when the motor achieves running temperature - please let me know.
Thanks.
Dan

Jan 29, 2010 | 09:29 PM

Conanski

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From: Ottawa, Ontario

That sounds like a classis TFI module failure, if you replace it be sure to get the same color replacement becuause they're different internally.

Jan 29, 2010 | 09:41 PM

ri_truck_guy

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From: Suffolk, VA USA

When you install the new TFI make sure you use dialetric grease. Heat failure is the big cause of TFI modules checking out, and that seems to match your symptoms.

Jan 29, 2010 | 10:32 PM

radicalmechanical

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Quote:

Originally Posted by Conanski

That sounds like a classis TFI module failure, if you replace it be sure to get the same color replacement becuause they're different internally.

I already replaced that, but I will look at the old one and make sure it was the same color. I didn't grease it up though. It is mounted on the fender within a heat sink. I was calling it the Ignition control module.
Thanks

Jan 30, 2010 | 02:09 AM

radicalmechanical

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Quote:

Originally Posted by ri_truck_guy

When you install the new TFI make sure you use dialetric grease. Heat failure is the big cause of TFI modules checking out, and that seems to match your symptoms.

I think on later models like mine these TFI or ICM's are relocated on the fender with a heat sink.. away from the distributer and thus the heat. I already changed this unit, but maybe I got a bad one from Napa.. I guess I'll get a new one tomorrow and see if that is it.
Thanks

Jan 30, 2010 | 07:44 AM

ri_truck_guy

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From: Suffolk, VA USA

Yeah....I had thought about that and had looked up both the ignition module and distributor for a 95 before I answered. Both showed as the distributor mounted unit. Looking back at it now I find about 2 of the 17 listed are fender mounts.....

Jan 30, 2010 | 10:54 AM

F150xlt

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From: Baltimore

It appears you've replaced everything but the distributor itself.
Inside the distributor is the Stator. When that fails you'll get no spark or
spark at the wrong time.

To replace the stator requires you press off the distributor driven gear and shaft.
If you don't have the proper tools purchasing a rebuilt distributor is easier.

Stator = $20.00
Rebuilt distributor = $60.00

The white paste you smear on the heat sink that the Ignition Control Module
bolts to is called heat sink compound or silicone thermal paste.