rough idle
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Junior User
Joined: Nov 2009
Posts: 55
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rough idle
1992 f150 4x4 5.8 efi
this truck has been running fine til i let it set for a couple days, now it idles rough(almost like i have a big cam) and wont idle at all when cold.
I cleaned the iac and tb with no change, if i let it idle while spraying carb cleaner in the tb, the engine smooths out, could this be caused by a sparkplug? maybe...help please
this truck has been running fine til i let it set for a couple days, now it idles rough(almost like i have a big cam) and wont idle at all when cold.
I cleaned the iac and tb with no change, if i let it idle while spraying carb cleaner in the tb, the engine smooths out, could this be caused by a sparkplug? maybe...help please
Cargo Master
Joined: Jul 2009
Posts: 2,538
Likes: 54
From: Des Moines
It could just be a matter of air in the fuel lines.
I've had issues in the past w/ my 91 F150 where after I let it sit for a couple of days, the fuel lines seem to completely drain. If I don't give the fuel pumps enough time to prime the fuel lines before turning the key to start it, it will run rough.
Are you familiar with how you're supposed to hear the fuel pumps run for a second after the key is turned to on? If so, repeat this procedure about 5 or 6 times before attempting to start it. If you get it started, use the gas pedal to prevent it from dying if it's still running rough.
When I experience this problem, it takes a good solid 1/2 hour of running the truck before the issue straightens out.
I've had issues in the past w/ my 91 F150 where after I let it sit for a couple of days, the fuel lines seem to completely drain. If I don't give the fuel pumps enough time to prime the fuel lines before turning the key to start it, it will run rough.
Are you familiar with how you're supposed to hear the fuel pumps run for a second after the key is turned to on? If so, repeat this procedure about 5 or 6 times before attempting to start it. If you get it started, use the gas pedal to prevent it from dying if it's still running rough.
When I experience this problem, it takes a good solid 1/2 hour of running the truck before the issue straightens out.
Fleet Owner
Joined: Oct 2005
Posts: 20,780
Likes: 1,746
From: Kentucky
It is always a good idea to do a tuneup if you do not know the age/mileage on the plugs/wires/cap/rotor/filters. No sense spending money on other parts until the basics are taken care of.
Many times there can be a code stored without turning on the Check Engine Light, therefore I would also check for stored codes or other problems with the KOEO tests.
Many times there can be a code stored without turning on the Check Engine Light, therefore I would also check for stored codes or other problems with the KOEO tests.
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Laughing Gas
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