Rough Idle After Cold Start
06-08-2018, 09:27 AM
#1
Member
Thread Starter
Rough Idle After Cold Start
1987 F150 XLT Lariat 302 5.0 120,000 miles
I've had this issue for a little while now. In the past month, I changed the fuel relay and the in tank pump/ sending unit assembly. Over the past year, I've updated most parts, including the EGR valve and sensor, MAP sensor, spark plugs and wires, IAC valve, PCV valve, fuel filter, air filter, o2 sensor (replaced again this morning, 2000 miles after initial replacement). Each morning it revs from approximately 400 to 1500 RPMs and when leaving work after it has sat for several hours. I simply can't figure out what is causing it. Before changing the fuel pump and relay, it stalled multiple times on the road within a few miles, so I parked it and drove a borrowed vehicle until I replaced them. Yesterday, I left for lunch at work (parked for about 5 hours) and it started/ idled rather well. If it always started and idled like that, I'd certainly not be worried. However, when I parked to get my mail and left it run during the lunch break, it stalled. No strange noise or anything; just stalled. It started right back up with no idle though.
Any ideas or suggestions? There's no white build up that would indicate a blown head gasket. It sat for about a month, so perhaps some condensation is in the gas tank and lines? I'm stumped.. Thank you for any help
I've had this issue for a little while now. In the past month, I changed the fuel relay and the in tank pump/ sending unit assembly. Over the past year, I've updated most parts, including the EGR valve and sensor, MAP sensor, spark plugs and wires, IAC valve, PCV valve, fuel filter, air filter, o2 sensor (replaced again this morning, 2000 miles after initial replacement). Each morning it revs from approximately 400 to 1500 RPMs and when leaving work after it has sat for several hours. I simply can't figure out what is causing it. Before changing the fuel pump and relay, it stalled multiple times on the road within a few miles, so I parked it and drove a borrowed vehicle until I replaced them. Yesterday, I left for lunch at work (parked for about 5 hours) and it started/ idled rather well. If it always started and idled like that, I'd certainly not be worried. However, when I parked to get my mail and left it run during the lunch break, it stalled. No strange noise or anything; just stalled. It started right back up with no idle though.
Any ideas or suggestions? There's no white build up that would indicate a blown head gasket. It sat for about a month, so perhaps some condensation is in the gas tank and lines? I'm stumped.. Thank you for any help
06-09-2018, 01:43 AM
#3
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Thread Starter
I drove home today after work, about a 3 mile drive. It started better than it has in a long time, with no eratic idling. It stalled 4 times, but started back up every time
03-14-2022, 04:32 PM
#4
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Rough idle and stalling
so my 87 4.9 will start up fine but idle rough for about 10 minutes or so. if i and idling at a stop it will also stall out. i’m sure there is a lot that it could be but if someone wouldn’t point me in some direction it would be much appreciated.
03-15-2022, 11:46 AM
#5
When I had this sort of issue I searched and searched online, until I finally came across a post stating to check the fuel vapor cannister. When I tried blowing into it I found that it was clogged, probably just from old age. Replaced it and the problem went away.
03-15-2022, 11:54 AM
#6
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