I have a 1991 chevy k1500 had new motor put in since we got it back will start right up on first start then if you let it warm up it is very hard to start almost like battery bad but it will eventually start anyone know what could be causing this timing battery bad starter ?

 

If you r close to a DIY store, Auto zone,advance auto...etc, take it there after it warms up and have them do a check on the starting and charging system. My 98 did the same things, and from the past, old school mechanic, chevy's had a problem long long time ago with starters getting hot and dragging. Well i took mine and it was the battery... good luck and let's us know what you found. Also check you cable's for tight fits, and clean connections

 

Hi lilrebel,

Welcome to the Chevy Forums.

ASSUMING, of course, you've changed the battery cables by now, and the engine ground strap:

I went round and round with this problem a while back with an old Belair 350. There's a few possibilities:
1. Choke out of adjustment

2. Cracked Heads

3. Faulty Head gaskets

4. Faulty vacuum hoses.

5.Warped valves which don't act up till the engine's hot.

The best thing you can do is give a cold and hot compression test to try to localize the problem to a specific cylinder bank.

It would also be wise to run a vacuum gauge till you discover the source of the problem.