What's Wrong with my Bronco?

[Erkal]

I have a 1986 ford bronco II, 2.9. If I have a fully charged battery or if I jump start it, it will start and run forever but after Running for a while, if I shut it off and try to start it again the battery will be totally drained. I have replaced the altenator which didn't fix it, and I have tried different batteries and same thing.
Some one please shine some light on this. I can't figure it out. Thanks.

[alaskan155]

take a voltmeter to the battery and see if its around 14v,while running thats means the alternators working properly, if it says about 12v or less it could be the wiring or in the alternator somewhere

[gertsdsbs]

Mine did the same thing and it turned out to be the ground wire. it looked fine but the inside was all corroted. Good Luck!

[TheCiscoKid]

x2 on checking the wires, even if they look fine they can be corroded on the inside. Check their connections first though, then replace the wires.

[JamesC]

make sure you don't have a draw on the battery with the key off check for dome light staying on, stuff like that. Also as said check running voltage to see if it is charging, you can use a jumper cable as a temporary ground if you don't have extra cables lying around.

[kroed11581]

My 88 did the same thing, turned out to be that when the battery cables were replaced, they routed them too close to the exhaust manifold, the cables would heat up and not conduct electricity down to the starter. For the cost to replace the battery cables, I'd try that first, making sure to route the cables away from extreme heat sources.

[Erkal]

Thanks every one I will take a look at all this and see if it works thanks