Slow to no cranking at times

[Laneman25]

5.0 GL Cranks slow at times, sometimes it's fine. All cables in engine area clean and tight. Battery at 12.8, 14 volts while running. Ignition switch? Starter? Solenoid? How do I narrow it down?

 

[Scott Danforth]

pull the plugs, does water shoot out the plug holes?

did you clean all the battery cable connections with 150 grit sand paper?

 

[Laneman25]

I cleaned the pos terminal cause it had some green powder starting. Neg looked good on outside but I didn't clean it.

 

[Bondo]

I cleaned the pos terminal cause it had some green powder starting. Neg looked good on outside but I didn't clean it.

Ayuh,.... Clean both ends, of both cables,.....

 

[bruceb58]

While cranking, measure voltage drop in the negative cable followed by the positive cable.

Measure the voltage of the battery to see what it drops to while cranking. The voltage should be lower than between 9.6V and 10.0V.

 

[itsathepete]

Ayuh,.... Clean both ends, of both cables,.....

What Bondo is saying in not as many words is don't forget to clean the negative terminal and grounding post on the engine block.

 

[Donald0039]

Could be bad solenoid. Or even bad starter. Load test the battery with a carbon pile load tester set to 1/2 CCA for 15 seconds. Read voltage at the end of 15 seconds.