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Discussion Starter · #1 ·
Been pulling my hair out on this for over a year now. So far replaced solenoid, coil, starter (x2), alternator, fan clutch, and battery (x2). Truck starts fine cold (when battery is charged) but after it warms up it barely cranks like its drawing too many amps. When in this condition, you can't jump it either.

I've been told to replace the distributor cap/rotor next, but I don't want to spend any more money until i have a more informed diagnosis. I believe the previous owner disconnected the check engine light too, so not sure if I can pull any codes or not.

Appreciate all feedback in advance!
 

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After trying to crank, grasp each of the battery cables and see if one is warm/hot(be careful), the one that has an elevated temperature is the one that has an increased resistance, either from a loose connection or possibly a deteriorated cable(hard to see if it's occurring under the cable's insulation). X3 on checking grounds. The factory cable that runs to the starter is adequate but a 2ga or 0ga cable would be better. Hope this helps and hope you get it figured out.
 

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If you have a high mileage engine, with loose pistons, it could be piston skirt drag when hot. I know it sounds backwards but loose pistons can sometimes run hot enough to swell the skirt and cause what seems like starter drag. To prove or disprove skirt drag, flood the engine when hot starting. If it spins faster when flooded, the fuel has cooled the pistons enough to shrink the skirts.


Richard
 

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1990 Ford Mustang LX 351M powered!! Project Cherry Bomb!!
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Completely unrelated, but I had a friend w a 1980 F100, 300 6 cyl, had a lil over 250,000 miles on it... Had so much piston slap you'd think the guides that guide the pistons from one hole to the other were gnna fly out of it till it warmed up!! Sounded like a bucket of bolts till it warmed up, then it was just fine... Smooth as silk... He said he'd rather have it like that, skirts and guides stayed oiled up good and he got about 20 mpg so he just drove it like that... And yes it did use oil... 1 qt every 7,500 miles, which was when he changed it.. Sorry the piston slap reminded me of that old truck..
 

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Discussion Starter · #10 ·
After trying to crank, grasp each of the battery cables and see if one is warm/hot(be careful), the one that has an elevated temperature is the one that has an increased resistance, either from a loose connection or possibly a deteriorated cable(hard to see if it's occurring under the cable's insulation). X3 on checking grounds. The factory cable that runs to the starter is adequate but a 2ga or 0ga cable would be better. Hope this helps and hope you get it figured out.
You da man!!! I finally got out to try it today. The truck wouldn't start, and the negative battery cable was warm to the touch. I finally located its block ground behind the wheel well liner. I immediately noticed a section roughly 1" long with no insulation left on it. I removed the frame mounted clamp, and the cable literally fell away from the block. The connection was completely corroded.

I took the ground bolt all the way out of the motor and cleaned both ends with a copper brush. I also cleaned up the wire keeper bracket to ensure a good connection. I dosed both sides of the bolt with dielectric oil, screwed it back into the motor, slid a new 4 gauge ground cable on the bolt, and secured with nut and lock washer. Finally, I connected the new ground wire to the battery and the little chassis ground to the fender.

Turn the key and ba bam!!! Super energetic crank and immediately fired up! Drove it to town to get gas and make sure it was good and warm. Came home, shut it off, waited a couple second, and turned the key again... Ba bam!!! Fired up again like brand new.

Thank you, thank you, thank you, for the recommendation fellas, I really appreciate your help!
 
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