Over the past couple months my truck (351w) has had an intermittent "slow" start, that has steadily gotten worse. Every couple cold starts, it will crank very slowly, like the battery is low. Fast enough to start, and then it runs fine and voltage is normal. Other times it cranks normally. When the engine is warm, it almost always cranks slowly.

Today when it was 25 degrees outside, it cranked so slowly I was afraid it wasn't going to start.

The battery is only about a month old, brand new Autocraft Platinum, 1000/850 amps. Cleaned the cables and connectors to the battery, which seemed to help a bit, but it's still slow. Cleaned the ground on the body right next to the battery, didn't help.

Maybe unrelated, but only recently when it is cranking, the tach goes bonkers and flicks all over the scale. As soon as the motor starts it works normally.

The starter looks to be the original, though the cable looks a bit newer. Truck is a 93 with 136,000 on it.

 

most likely a bad battery. yours may have too low of cold cranking amps. have it tested first, and before you say anything i'm gonna say i dont care if its new.

 

Yes, the battery holds up to my load tester just fine and maintains proper voltage under load. The factory spec for the motor was a 800/650 amp battery, so the 1000/850 should be more than sufficient. Same rating as the one that came with the truck, which was over 8 years old.

The odd thing is that it does this every so often, not consistently poor cranking.

Also, the starter almost always grinds for a bit when releasing the key after it starts. It didn't used to do that either. That would seem to be a bad solenoid, but it could mean the whole thing is going bad.

 

Change out the starter.... That sounds like the same symptoms I had with my starter on my '97....

What happened first, is my 6 + year old battery lost a cell, so I replaced it. But, even after getting a new battery, that also passed all tests and the alt pumps out 14v as well, it still had a slow spin to it. I already had a new starter, because when it first acted up, that's what I thought it was, so I got a new starter, but it turned out to be the battery, but that's not important now!

Anyway, I swapped out the starter and it's been great every since, and that was 5 months ago to date.

Mitch

 

ok good then that can be erased from the possibilities. sorry i put it the way i did. i just get tired of some people thinking that new means there wont be anything wrong. anyways i'd agree with mitch sounds like the starter. yours should be just like mine and its pretty easy to change out. mine was a 1/2" and 9/16" for the mount bolts and a 1/2" and 11/32" for the wire nuts. mine was new when i got mine so the wire nut sizes may be different.