GMC, Sierra, 1993, 6 cyl 4.3, 4x4. Checked the voltage on the battery & it reads 12.7 volts. Took the starter to be tested & it failed. I replaced the starter, but when I go to turn the engine over all I get is a click sound & the lights dim. I tried charging the battery, still the same. My charger has a 50 amp jump start this also did not produce any change. What could the problem be? Is it possible that the new started is bad? Thank you for your time and attention.
Check to see if you can turn the engine by hand. If you can't turn the engine you will need to diagnosis why it won't turn.
A common fault is when a head gasket leaks and fills the cylinder with coolant (hydro- lock). Take the spark plugs out of the engine and try to crank the engine over if it does and coolant sprays out of one or more cylinders you may have a faulty head gasket, cracked head or block.
Let me know if the engine turns, we can diagnosis the problem further from there.
I had a load test on the battery and it was pushing out only 30 amps. Problem solved thanks.