Hard start after S10 is warm

[don]

My 1985 Chevy S10 2.6 engine cranks fast on a cold start, but after the
engine is hot it cranks slow as if the battery was bad. The rebuilt engine
is only 5 years old and the battery is about 2 years old.

[Bill]

Place jumper cables on the battery from another car and see if it cranks as
it should when warm.

If yes, then check battery and alternator. (If the alternator is not
charging the battery, the battery could be slowly losing its charge.)

Also check all main electrical cables for clean tight connections. This
includes the main large ground wire going to the engine which the alternator
would use to charge the battery.

Checking the battery voltage with a multimeter...

The battery should read 12 something volts with just the ignition on (not
started).

Then start it and it should then read 13/14 volts at the battery. This is
the alternator kicking in and charging the battery.

"don" wrote in message