own a 1981 F-100 with a 300 inline six cylinder. The truck willl turn over but not start. I have checked the timing and it is okay. I have replaced ignition coil, plugs, wires, everything else has already been previously replaced.. even rebuilt the carburetor... has spark but will not start. It is getting fuel. It tries to start but wont. got her running on 3 separate occasions and she died within a week.. the odd thing is that the truck killed a brand new battery, but the alternator tested fine... I can't seem to find the problem. Help!

Thanks in advance

 

You need three things for the engine to run; fuel, spark and compression.
Have you done a compression test?

Re: Your battery
Was the alternator tested for output only?
An alternator can have a bad diode and still produce power when turning.

There are a few 4.9 gurus here.
JimsRebel and 86F150six come to mind.
I don't think replying to a thread that's over 10 years old is likely to get you much help.

 

When cold, is the choke plate completely closed? This would explain the engine not starting [if plate is closed hard], but not the fact that you had it running 3 times, but died within a week?