engine stalls when warmed up?
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New User
Joined: Aug 2009
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engine stalls when warmed up?
i have a 1990 f-150 4.9 inline six, and when it gets warmed up, the rpm's will drop to about 300-500 then shoot up to 2000 and then it just die's. it takes about 5-10 minutes for it start back up. could this be the gas cap or vapor lock? other wise it runs great, it also has about 200.000 miles on it.
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so is mine. i replaced a lot of things on it. i hooked it up to a computer and the first code it pulled, was the throttle position sensor. i also noticed the gasket that goes between the throttle body and the intake was totally destroyed. replaced the tps, the map sensor, the idle air control module, damn near all vacume lines amd it still does it. i noticed the other day that the vent hose on the filler neck was missing. they replaced that hose with a rubber hose that goes straight to the tank with no vent hose, and the gas cap is a non venting cap. i am pretty sure thats my problem. i drove it for a while with out the gas cap, and had no problems. but we'll see.
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well mine quit alltogether, now I'm not showing any fuel pressure and the truck has 3 pumps on it, so I can take that to two because I only use the front tank, I never looked into it but the guy I got it from said something was up with the rear tank, so what pump is not working? any ideals?
Lead Driver
Joined: Aug 2006
Posts: 5,670
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From: Sand Lake, MI
well mine quit alltogether, now I'm not showing any fuel pressure and the truck has 3 pumps on it, so I can take that to two because I only use the front tank, I never looked into it but the guy I got it from said something was up with the rear tank, so what pump is not working? any ideals?
Sounds like you where running, barely, on the low pressure pump in the tank but it died?
However its equally possible I guess you where running on the high pressure pump only with the fuel siphoning to it from the tank just fast enough to keep it running.
Either way with no pressure reading, and knowing the pumps do get power, you're going to have to test the pumps for pressure and flow rate, replace whatever pump or pumps that do not meet the minimum requirement.
