My 1990 Ford F-150 stumbles, wants to die when the weather is very hot

Tiny
3DUCKS
  • 1990 FORD F-150
  • 165,000 MILES

I have a 1990 Ford F150, 300 cu in 6 cylinder engine with 5-speed tranny. Recently (and after I have been driving it for awhile). And when the weather is at or above 100 degrees. The pickup has started stumbling, bucking, and refusing to take fuel and accelerate. This only occurs when the weather is extremely HOT though, never when the weather is cool. When this incident occurs, the engine slows until I can barely tell it is running, and slowly comes to a stop. The pickup ACTS like is running out of fuel; but it isn't. The "Check Engine" light always comes on at this time. However, if I floor-board the gas pedal the pickup immediately takes off "like a scalded cat" for the short time I am floor-boarding the throttle. This incident continues until I stop and shut the engine off. When I stop, turn off the engine and let the pickup sit for 5 minutes or so, it starts up and runs like new once more?

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Tuesday, September 27th, 2011 AT 6:44 PM

5 Replies

Tiny
ASEMASTER6371
  • EXPERT
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Sounds like a fuel pressure issue. It sounds like a vapor lock condition when it is hot and fuel is actually boiling. You need to have the pressure checked to verify.

Roy

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Tuesday, September 27th, 2011 AT 6:57 PM
Tiny
3DUCKS
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Thanks for the reply. I will do as you say.

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Tuesday, September 27th, 2011 AT 7:49 PM
Tiny
ASEMASTER6371
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Good luck

Roy

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Tuesday, September 27th, 2011 AT 8:11 PM
Tiny
MILTON PLYMALE
  • MEMBER

Bite in the rear end. 1987 F150- a work in progress. Just turned over to 133K. Before body work, I thought I had it done. Run 180 miles, turned it off, and it would not start. When the engine is warm, it will not start. Asked an elder- hot-spot on the coil? He suggested vapor lock. I hadn't heard of that since the '70's ! Could be.

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Saturday, July 22nd, 2017 AT 9:46 AM
Tiny
2CARPROS KEN
  • ADMIN
  • 11,708 POSTS

Great addition to this thread! Please feel free to help out whenever you are on the site :)

Cheers, Ken

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Monday, July 24th, 2017 AT 11:45 AM

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