Help, seize when cranking on cold starts

[HawkDsl]

pre-1996, sir.. the gmt400's were OBD1, TBI, all the way thru 1995.

Richard

I'm so happy I have a pre 94, and a pre 96 truck .. and owner #1 of said truck!

 

[Mossback]

Hey guys, back again. Haven’t been able to work on the truck all winter. Have my volt meter with me here now. Battery with cables unhooked tests good at 11.5v as soon as I hook up the grounds and the cable that runs from the fuse box under the hood to the positive terminal the voltage at the posts drops to 8-9v

 

[Mossback]

That’s 9v with the key on, if I pull the 40a fuse (ignition A) with the key on the voltage goes up to 10-11v

 

[someotherguy]

No load at all battery disconnected showing 11.5V, that battery is discharged. I'd start by giving it a full charge first. Sounds like there's other issues still, but that battery needs to be fully charged before any of your other results have meaning.

Richard

 

[Mossback]

That’s 9v with the key on, if I pull the 40a fuse (ignition A) with the key on the voltage goes up to 10-11v

If I jump it I can eventually get it to start and run. The alternator does charge.

 

[Schurkey]

11.5 volts on a "12-volt" battery is TOTALLY DISCHARGED.

You'll be lucky if that battery recovers after being charged overnight...maybe all day.

And if it was that discharged during freezing weather, it's probably ruined.

 

[Mossback]

Copy that, I’m going to try a new battery.
would that have any explanation for that voltage drop when hooking up the positive cable?

 

[someotherguy]

Copy that, I’m going to try a new battery.
would that have any explanation for that voltage drop when hooking up the positive cable?

Weak or defective battery showing 11.5V wouldn't surprise me at all for it to drop significantly when any load is applied.

You should try fully charging it first.

Richard

 

[Mossback]

Wow.. that battery was less than a year old. But it was indeed faulty. Warranty covered a new one and all is good!! Sorry I feel like an idiot I need a legit battery tester.

Still has a slight stop/hesitation when cranking right before it fires though?

 

[Schurkey]

Excess initial timing advance?

What is the amperage draw of the starter?