Engine Rough, help please
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Joined: May 2003
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Engine Rough, help please
Folks,
The engine in my F150 has started running rough. Runs rough at speed, but seems to idle fine. I cannot distinguish if it is fuel or electrical. Here is what I have done to date. I have replaced the fuel filter, and the O2 sensor. The air filter is clean, and I added a bottle of fuel conditioner to remove any possible water in the tank. So far, none of these have helped. The "check engine" light does not come on. The dist cap, plugs, and wires were replaced about 6 months ago. I have not replaced the coil. Plugs and wires appear to be dry. Fuel pressure is 45 psi and vacuum is 21 inches.
Engine details: 1989, f150, 4.9l, 6 cyl, fi.
Thanks in advance for any comments or suggestions!
Stan
The engine in my F150 has started running rough. Runs rough at speed, but seems to idle fine. I cannot distinguish if it is fuel or electrical. Here is what I have done to date. I have replaced the fuel filter, and the O2 sensor. The air filter is clean, and I added a bottle of fuel conditioner to remove any possible water in the tank. So far, none of these have helped. The "check engine" light does not come on. The dist cap, plugs, and wires were replaced about 6 months ago. I have not replaced the coil. Plugs and wires appear to be dry. Fuel pressure is 45 psi and vacuum is 21 inches.
Engine details: 1989, f150, 4.9l, 6 cyl, fi.
Thanks in advance for any comments or suggestions!
Stan
Post Fiend
Joined: Nov 2002
Posts: 9,987
Likes: 7
From: Memphis, TN
Engine Rough, help please
Pull the codes anyway, do the tune-up procedure on the emissions sticker, and diagnose the ignition system. Check compression, timing, and vacuum. (How the needle behaves is more important than the number.) Compare your spark plugs to the pics in the back cover of the Haynes manual.
