I have an 89 GMC Jimmy that was given to me in what was described as good condition. It started fine in warm weather…Now that it is cold I have to charge the battery each morning before plowing…But after I charge I can plow for 20 minutes but then when I go up a slight incline and give it gas it stalls out, and then I have to jump it again…Any ideas?
The battery problem: have the charging system checked. Check for parasitic draw. With multiple discharges your battery probably needs replacing.
Stalling out: Ignition system ( plugs, distributor, wires)? Fuel system—weak/failing fuel pump, fuel filter, injectors?
Older truck, lots of potential problem areas.
I’m not the mechanic in the group, but that sure sounds exactly like how the cars I have owned with bad alternators behaved.
It sounds like the alternator isn’t charging the battery. Does the battery warning light, along with the other warning lights, turn ON when you turn the ignition from OFF to ON? It is critical to the alternator operation that the warning light works properly. If the warning light is working okay then check the voltage at the battery while the engine is running around 1,500 RPM. You should have around 14 volts getting to the battery. Make sure the battery connections are clean and making good connection to the battery and the main alternator lead is tight and not damaged due to heat, which would indicate a bad connection. You should also have your batteries checked out to see what kind of condition they are in. You may have two used up batteries. Having a load test done on the charging system will tell you what is going on with the charging system.