art

OK, my 1991 F150 had a rebuilt 5.0 about 4 years ago. Original otherwise. I drive it rarely (once every couple of weeks). Truck has been running OK except lately it started running rough and stalling before it warms up. The first time it happened I had lots of blue smoke from tailpipe. I thought I blew a gasket but smoke dicipated and comes back occasionally and only slighly. I can start back up usually, but need to floor the gas pedal and run on high RPMs for a minute or so and then it's fine. It's almost like it floods with gas and I need to burn it off. If I try to drive right away before the "pedal on floor" procedure, I am almost guaranteed to stalll once I start driving. Stall is most likely if I put into drive, if I let idle, it may be fine. I took it to a mechanic and he could not find the problem. Engine ran fine for him. Drove off and truck stalled on way home. Went back and he replaced coolant temp sensor and looked at distributor. Drove home but problem returned next time I drove it. By the way, the truck just passed an emmission inspection too at another shop (after it warmed up). I was actually hoping it would fail and they would find the problem, but it ran fine for them. Any advice? Neither mechanic doesn't seem interested in this job, too much of a headache I guess for not enough money.

dr_bowtie

replace teh 2 wire temp sensor....

blue smoke is rich....very rich...cap/ rotor and plugs/wires all new?

art

cap and rotor not brand new but couple years old when engine was replaced. mechanic said they were fine. I will check which temp sensor was replaced. did not know there were two of them. thanks

DrBill

my '90 F150 is exhibiting similar behavior. Were you able to get it fixed? I is puzzling to me. No one has been able to give me a reasonable explaination to fix it's behavior. It starts fine, but can run REALLY rough until it gets warm. Similarly, like it is flooded. Off idle doesn't seem to help very much. Sometimes, it doesn't have issues. It may need plugs, wires, distributor, etc. But it does not explain this senario. AND when it does warm up - it's fine. Again, it starts fine from stone cold, and runs well when warmed up. It's the 3-20/30 minutes that the vehicle is undrivable.

Thanks.