ok ive got a 89 F350 7.5L Dump,
just rebuilt motor, replaced fuelpump gas/brake lines
i believe i didnt connect alternator correctly, it ran till the batt was drained and died. wont start unless i got it hooked up to batt charger and dies when out of juice. now the 2 connectors are connected but it looks like a wire went to the back of the alt. but there is no wire.. what am i missing?

 

Just two plugs.

Change the charging plug (the one with two orange/black wires) for a new pigtail, always.
Ford has a TSB on this.

 

ok i tested the continuity of the plugs with a DOVM and the connections are good. also took the alternator to adv auto and it passed. so now i know its not the connections or the alternator... but why would the truck only run with the jumper charger and die when the charge runs out. the batts dead completely would that cause the issue?

 

Deadbattery could do it, the alt needs power to produce power. I'd put a slow charge on the battery and fully charge it.

 

Does the green/red wire have power when the key is in run?

If the battery has nothing then there might not be any signal to turn on (excite) the alternator.

Be careful trying to run with a dead battery.
This can overtax the alternator and burn it up.
It's always best to charge the battery first.

 

ok so i got a new battery, $104 champion battery. now it cranks, it starts, runs for 5secs and shuts off. doesnt seem to be pumping a steady stream of gas. only gets enough to start it and then just stops. the fuel pump was replaced along with both fuel filters, so that couldnt be the problem. i pulled the gas line off the carb and put it above the carb and watched it feed while my dad cranked it. gas till it started then nothing.

 

You have no oil pressure, or the fuel pump relay is not getting power.
There is always power to the pumps while cranking.
When you release the key, power to the pumps comes through the inertia switch, and then the oil pressure sender, to the fuel pump relay.

You need to check these three things.

 

alright would u happen know where i can get a diagram showing me where the inertia switch is? and the pump relay?

 

The inertia switch is inside the passenger side of the cab.
Either in the kick panel or mounted by the transmission tunnel.
It has a white reset button.
This is to shut off the fuel pump in the case of an accident.

The fuel pump relay and fuel selector relay should be mounted to the firewall in front of the driver.

User 'subford' had a diagram in his photobucket account, but it seems to have been deleted.
Here is a schematic,

https://www.ford-trucks.com/forums/a...6&d=1218602346