351M wont run
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Freshman User
Joined: Sep 2001
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351M wont run
iv got a 79 F-150 4x4 with a 351M. it will start right up but as i let go of the key it stalls. iv replaced the starter solenoid with one i know works from my 78 F-100.I also replaced the voltage regulater and ingnition box from my 79 F-250. the f250 didnt have a moter in it when i got it so i dont know if these parts work. any sujestions thanks
Posting Guru
Joined: Jun 1999
Posts: 2,415
Likes: 3
From: Comox Valley, Canada
351M wont run
Could be the wire from the igniton switch "run" position, pink/black stripe, is broken. Seen it before.
What is happening is you are getting 12volts from the starter relay "I" terminal, for initial start. But as soon as you let the key go and it returns to "run" position there is no voltage to "+" of the coil.
Try running a wire from the battery positive to the "+" of the coil. Then start the truck. If it keeps running that is the problem.
You really shouldn't run the truck for an extended period like this, could be hard on the coil. Make sure after you are finished running the engine to disconnect the jumper from the battery to the coil.
The pink/black striped wire is a resistor wire used to drop the voltage to 8-9 volts to, as I understand it, extend the life of the coil. It drops the voltage by resistance, which causes heat, which breaks down the wire after time. Resulting in at least a no run condition. But what I have usually seen and fixed is a burnt up wire bundle behind the dash.
Hope it is just a dead wire.
Sparky
What is happening is you are getting 12volts from the starter relay "I" terminal, for initial start. But as soon as you let the key go and it returns to "run" position there is no voltage to "+" of the coil.
Try running a wire from the battery positive to the "+" of the coil. Then start the truck. If it keeps running that is the problem.
You really shouldn't run the truck for an extended period like this, could be hard on the coil. Make sure after you are finished running the engine to disconnect the jumper from the battery to the coil.
The pink/black striped wire is a resistor wire used to drop the voltage to 8-9 volts to, as I understand it, extend the life of the coil. It drops the voltage by resistance, which causes heat, which breaks down the wire after time. Resulting in at least a no run condition. But what I have usually seen and fixed is a burnt up wire bundle behind the dash.
Hope it is just a dead wire.
Sparky
Posting Guru
Joined: Jun 1999
Posts: 2,415
Likes: 3
From: Comox Valley, Canada
351M wont run
Another thought it could also be the ignition switch itself, could cause the same symptoms. It isnt a fuse problem, as the same circuit is used to close the starter relay.
Sparky
Sparky
