Ran for a month just fine. Now it will only start after being jumped. Everything worked just fine....WTF..... What should I test first?

 

What is the year/model/engine?

Does everything work normally once you get the truck started?

Check the battery terminals for corrosion and/or loose battery cable(s). If that doesn't work have the battery tested.

 

Thanks, The truck was sitting in a back field for about two years. The battery is brand new and all cables are tight. If you put your ignition key in and turn nothing happens but if I hook my other truck up I can get the engine to fire up. Alternator seems fine as well but none of the gauges will work.... I'm gunna run to O"Reillys later and see if I can rent one of those CPU testers and see if that tells me anything. Its just been a few years since I've had to deal with puters.... Just kinda weird because my buddy and I have taken this thing all over the woods and highway trips to test reliability for the last month with zero issues. I will say that 4.6 triton does a lot better on gas though.

Thanks.

 

You do not need a "CPU Tester". You need to fix the issue with the battery's inability to supply power to the rest of the vehicle. Just because a battery is "new" or connections are "tight" does NOT mean they are actually GOOD. They are only known to be GOOD when they are proven to work.

Use standard voltage drop measurements to isolate. Google it. You will need a multimeter.

 

so the truck will not crank, you jump it with A GOOD BATTERY and the truck starts... this is not rocket science..... What else do you think is happening when you jump with a GOOD Battery ?

 

neighbor had a truck last month that would not crank.. Found the positive battery clamp was a replacement unit clamped to the Original cable and the connection was corroded inside..

 

Speaking of, I've seen a few of those red/black painted replacement clamps with paint on the surface where it's supposed to make contact with the cable... They don't work very well for some reason.

 

Your not gunna believe this..... The negative battery cable was corroded about half way through insided the cable. Never seen that before but as suggested I tested everything even cables. Back on the road again. Thanks

 

Yeah, I believe it, I've seen it a number of times. That's why I told you to do the voltage drop testing.