I bought my son an old farm truck for his first and because I like F150's. We drove it home with a real rough idle and poor porformance...I expected a good tune up would help. Well, we can barely get it started and haven't driven it for weeks. It blows black smoke out when cranked and will not start. I replaced the pluges, wires, distributer and cap. It ran for about two days and acted up again...black smoke and all. Pulled the plugs and they were fouled. Put new ones in and it ran for a day. What is going on!!!
Sounds like it may be running ridiculously rich... but I don't know how to adjut the fuel mixture on that truck, only on the older carbeurated ones. Try asking this in the pre-1997 forum, they might be able to help out more.
Very first thing I would check is your air filter if you havent already done so. If that is fine next step would be KOEO to energize the fuel pump. Immediately pull the vacuum hose of the fuel press. regulator and look to see if it is wet. If so, you have a bad regulator. If it is dry, put a vacuum pump on it and pump it up to around 18psi, see if it hold vacuum. Check the voltage coming out of the O2 sensor with the engine running. Is the voltage switching (should be between 0-1 volt. If it is staying closer to zero that means the pcm is seeing a lean condition and will richen the fuel up. Pre-OBDII vehicles can be a real pain in the arse to diagnose as especially with fords, they didnt have a datastream til later years. Hope this helps. Keep posted
Take the Vac line off of the EGR. If the engine runs good then the EGR is bad, Or the cheaper fix, The vacuum control valve. Located in the middle of the block at the rear. You can follow the vac line around the rear of the motor to the controller. To test the vac control take the elect plug off of it, Start it up, If you still have vacuum at the EGR line, The vacuum control is bad. It sells for around $40.00.
Take the Vac line off of the EGR. If the engine runs good then the EGR is bad, Or the cheaper fix, The vacuum control valve. Located in the middle of the block at the rear. You can follow the vac line around the rear of the motor to the controller. To test the vac control take the elect plug off of it, Start it up, If you still have vacuum at the EGR line, The vacuum control is bad. It sells for around $40.00.
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1989 F150 4.9 inline 6 - will not start or run
Linear Mode
