Start when cold, won’t when warmed up!

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Jan 12, 2021 | 11:17 AM

Jordan Perry

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Start when cold, won’t when warmed up!

I have a 94 f150 that will fire right up when cold, but won’t when warm. Anyone ever have this issue? I haven’t looked at it much but just looking for some advice on where I should start. I do know the fuel pump is kicking in, I can hear it.

Jan 12, 2021 | 12:42 PM

jas88

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From: Greater Austin, Texas

See if it will start on starting fluid - that will tell you whether your problem is fuel or spark.

Jan 21, 2021 | 04:40 PM

midwestbird

Mountain Pass

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From: MO

Quote:

Originally Posted by Jordan Perry

I have. How is it behaving when you try to start it warm? Slow crank? My 4.9L would fire up cold, but when warm it would slow crank and barely start. Turned out to be bad ground wiring. I added stock ground wire that was missing, and added a few aftermarket straps too for good measure.

Jan 21, 2021 | 08:33 PM

seschenburg

Tuned

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I recently read that if you have injectors that leak when hot this can happen. Do you smell fuel when it won't start?

Jan 22, 2021 | 12:27 AM

TexasGuy001

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I had this issue on my previous 95 F150 5.0 years ago. It turned out to be bad injectors leaking on shutdown and flooding the engine. It would eventually start and then chug and puff black smoke. Try holding the pedal to the floor when cranking and see it it starts. That should be clear flood mode and shouldn't let additional fuel in. I know this applies to most EFI vehicles but never found out for certain if it applies to these trucks.

Jan 22, 2021 | 05:10 AM

Caleb H

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From: Pennsylvania

It depends on the noises it makes. If it seems like a fuel issue, definitely check into the advice that's already been given. If it is clunking or not even turning over, check the starter. I had personal experience with this. It sounds weird, but a starter that is cold may spin fine and start your truck, but after driving around, the heat from the engine can warm it up. If you make a quick stop somewhere and shut it off and go to start it again, the warm starter won't be as happy spinning and the truck won't start. I got stranded a few times in my truck until I realized what was going on and changed the starter, haven't had an issue since. Well, at least that issue, hah!

Jan 22, 2021 | 06:42 AM

wahvtec

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My 1993 did the same to me. It was the engine coolant temp sensor. Basically always said the engine was dead cold sending too much fuel when warm. It would start if pedal held wide open after a bit of cranking. Would not start at all with throttle closed. Its not the sensor associates with the gauge, just for the pcm.