starting problem - electrical
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Freshman User
Joined: May 2003
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From: the great northwest
starting problem - electrical
This is a 70 F100 302.
I'm having a problem with the start circuit. When I turn the key to the start position it sometimes takes forever to crank. Today it didn't want to crank at all. Then I noticed if I abruptly "let go" of the key, it would crank. So it appears as its not getting any juice during starting, but the run circuit is fine, and there is just enough momentum of the engine when you let go to start.
Recently, I replaced the starter key switch and the soleniod (under the hood on the sidewall) as I was having starting problems. This seemed to help, but I still have those hard to start problems, usually after the engine is warmed up. Today's problem happened after the truck was warmed up.
Any suggestions what could be the culprit?
Thanks,
Jeff
I'm having a problem with the start circuit. When I turn the key to the start position it sometimes takes forever to crank. Today it didn't want to crank at all. Then I noticed if I abruptly "let go" of the key, it would crank. So it appears as its not getting any juice during starting, but the run circuit is fine, and there is just enough momentum of the engine when you let go to start.
Recently, I replaced the starter key switch and the soleniod (under the hood on the sidewall) as I was having starting problems. This seemed to help, but I still have those hard to start problems, usually after the engine is warmed up. Today's problem happened after the truck was warmed up.
Any suggestions what could be the culprit?
Thanks,
Jeff
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Joined: Jun 1999
Posts: 2,415
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From: Comox Valley, Canada
I am assuming that you mean the engine turns over when you turn the key to "start" it just wont fire until you release the key to "run".
The power to the coil + during "starting" comes from the small "I" terminal of the starter relay(solenoid).
Since you replaced the relay maybe the wire that is on the "I" terminal is corroded or not on tight enough.
The wire goes from the "I' terminal to a splice where it meets the wire from the "run" circuit and the wire to the coil +.
Also is the truck still points equipped or have you upgraded to electronic ignition?
The power to the coil + during "starting" comes from the small "I" terminal of the starter relay(solenoid).
Since you replaced the relay maybe the wire that is on the "I" terminal is corroded or not on tight enough.
The wire goes from the "I' terminal to a splice where it meets the wire from the "run" circuit and the wire to the coil +.
Also is the truck still points equipped or have you upgraded to electronic ignition?
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Freshman User
Joined: May 2003
Posts: 31
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From: the great northwest
In response to Sparky - yes, the engine turns over but won't fire until you release to "run". It has been upgraded to electronic ignition.
There is some corrosion on the wires which I will check.
There is some corrosion on the wires which I will check.
Posting Guru
Joined: Jun 1999
Posts: 2,415
Likes: 3
From: Comox Valley, Canada
You can always run a new wire from the coil + to the relay "I" terminal.
The "I" terminal is only powered when the relay is powered closed when the key is in "start".
Quick fix and doesnt really change anything electrically
just eliminates a few feet of possibly bad wire.
If you do this just make sure you seal the old wire end as it can have voltage on it when the truck is running, and you dont want sparks flying around
Hopefully the truck was wired like a stock electronic system, if not all bets are off as I have seen some very creative wiring
The "I" terminal is only powered when the relay is powered closed when the key is in "start".
Quick fix and doesnt really change anything electrically
just eliminates a few feet of possibly bad wire.If you do this just make sure you seal the old wire end as it can have voltage on it when the truck is running, and you dont want sparks flying around
Hopefully the truck was wired like a stock electronic system, if not all bets are off as I have seen some very creative wiring
