1975 F100 Starting issues
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1975 F100 Starting issues
Hi my truck is a 75 F100 4x4 with a 351 cleveland, c4, and a dana 20. Yes I know this was never original in the truck. When I bought it it had problems cranking over like it wasn't getting enough battery power. I replaced the battery and cables. Now when the truck will start fine when its cold but after a few minutes of letting it run it doesn't want to restart. It will crank over but very slowly like its not getting enough power to the starter almost if the battery is going dead. I replaced the starter solenoid, and made sure all my grounds were clean and good. I did notice if I try to keep restarting it I can pull out the key and it will still try to turn over for a few seconds with out the key in. I am kind of confused on what the problem might be. Any suggestions? Thanks.
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Joined: Apr 2009
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From: Stanley, VA
I see you replaced the starter solenoid. Was it a quality (expensive) part or a cheap "off shore" piece?
Rock Auto has Motorcraft solenoids (SW-3) for $27.79. Expensive but well worth it.
You should also do a cranking amp draw test to see if 1) the battery is good and 2) see what kind of shape the starter is in.
Also, be sure the ground cable is connected to the engine block and the connection is clean and tight.
Rock Auto has Motorcraft solenoids (SW-3) for $27.79. Expensive but well worth it.
You should also do a cranking amp draw test to see if 1) the battery is good and 2) see what kind of shape the starter is in.
Also, be sure the ground cable is connected to the engine block and the connection is clean and tight.
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I see you replaced the starter solenoid. Was it a quality (expensive) part or a cheap "off shore" piece?
Rock Auto has Motorcraft solenoids (SW-3) for $27.79. Expensive but well worth it.
You should also do a cranking amp draw test to see if 1) the battery is good and 2) see what kind of shape the starter is in.
Also, be sure the ground cable is connected to the engine block and the connection is clean and tight.
Rock Auto has Motorcraft solenoids (SW-3) for $27.79. Expensive but well worth it.
You should also do a cranking amp draw test to see if 1) the battery is good and 2) see what kind of shape the starter is in.
Also, be sure the ground cable is connected to the engine block and the connection is clean and tight.
Hotshot
Joined: Apr 2009
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From: Stanley, VA
Probably best to take it to a shop to do that. I have an induction ammeter that allows me to test stuff but not everyone has one.
If the engine is cranking slow during the test and the ammeter shows low amp draw then I would say the battery is weak. If it shows a high amp draw I would say the starter is on its way out.
If the engine is cranking slow during the test and the ammeter shows low amp draw then I would say the battery is weak. If it shows a high amp draw I would say the starter is on its way out.
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Probably best to take it to a shop to do that. I have an induction ammeter that allows me to test stuff but not everyone has one.
If the engine is cranking slow during the test and the ammeter shows low amp draw then I would say the battery is weak. If it shows a high amp draw I would say the starter is on its way out.
If the engine is cranking slow during the test and the ammeter shows low amp draw then I would say the battery is weak. If it shows a high amp draw I would say the starter is on its way out.
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I totally forgot about that. Good point thanks! I just realized the red/orange connector on the back of the alternator was lose and barely attached so I put a new one on and snugged it down. Maybe my alternator was bad and wasn't charging the battery. Waiting for my battery to recharge right now lol.
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From: auburn, ca
make sure you have GOOD grounds. battery to block, block to frame and then the small unshielded braided ground strap from sheet metal to chassis. all the guys that posted are correct too, I am **** about using the good motorcraft starter relay. the last good part # I remember for them is a B7AZ-11450-AA. when amp testing starter draw, a good rule of thumb is .8 amp for every cubic inch. a 351 cid x .8 = 281 amps. if its more than that your starter may be drawing too many amps when hot. are you running headers that are close to the starter housing ? are your battery cables a small gauge ? I like running #2 gauge or bigger(smaller number).
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make sure you have GOOD grounds. battery to block, block to frame and then the small unshielded braided ground strap from sheet metal to chassis. all the guys that posted are correct too, I am **** about using the good motorcraft starter relay. the last good part # I remember for them is a B7AZ-11450-AA. when amp testing starter draw, a good rule of thumb is .8 amp for every cubic inch. a 351 cid x .8 = 281 amps. if its more than that your starter may be drawing too many amps when hot. are you running headers that are close to the starter housing ? are your battery cables a small gauge ? I like running #2 gauge or bigger(smaller number).
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update! So I just realized that braided wire ground was loose because the screw was stripped so i drilled a new hole and then cleaned off the paint in the area and retightened it. I think I might have solved the problem. It is about 12.50-12.55 volts at idle, and about 12.35ish when i turn on the headlights. When the car is off the battery was at 12.75ish.
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From: Stanley, VA
update! So I just realized that braided wire ground was loose because the screw was stripped so i drilled a new hole and then cleaned off the paint in the area and retightened it. I think I might have solved the problem. It is about 12.50-12.55 volts at idle, and about 12.35ish when i turn on the headlights. When the car is off the battery was at 12.75ish.
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Yea that's what I was thinking. I was trying to remember what it was supposed to be. 12 didn't seem right for while it was running. So I just noticed I have another black wire on the back of the alternator that is not connected to anything. It looks like it has one of those connectors that slip onto a flat piece of another connector. Like a male/female connector. The one on the back that's not connected to anything looks like the female side. I'm not sure what to connect it too. Thanks
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From: Stanley, VA
No telling what kind of wiring repairs have been done by previous owners but from the factory there were four electrical connections at the back of the alternator.
The heavy black wire goes to the "BAT" or "+" terminal, the orange wire goes to the "F" or "FLD" terminal, The white w/ black trace goes to the "S" or "STA" terminal. The fourth connection is a ground and that terminal is actually the mounting tab for the rubber strain relief.
The heavy black wire goes to the "BAT" or "+" terminal, the orange wire goes to the "F" or "FLD" terminal, The white w/ black trace goes to the "S" or "STA" terminal. The fourth connection is a ground and that terminal is actually the mounting tab for the rubber strain relief.
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Awesome! Thanks for the picture! That really helped. All of the large 3 wires appear to be connected to the right place then. What do u mean about the rubber strain relief? What/where is that? Thanks!