First off, I think you mean that you are having to "roll start" the truck - right? ("Pull starting" is something you do to a lawnmower - unless your truck has a pullcord.)
Next time this happens, have someone hold the key in the "Start" position (like you're trying to start the engine) while you tap the starter motor with a ball peen hammer in a few different places. You will probably find that this makes the starter turn over.
The problem is more than likely a bad spot in the starter motor armature where the commutator brushes contact the armature.
This probably does not happen every time you go to start your truck (unless the armature and/or brushes are in real bad shape), and the reason that it does start after that is that the vibration from tapping it w/a hammer or "roll starting" the engine vibrates (and/or heats up) the dicey connection where the brushes are supposed to contact the commutator on the armature, allowing them to pass electrical current on to the armature.
You can try to take the starter motor apart and lightly sand the armature till the copper contact strips are clean (and check the condition of the brushes while you're at it), but it's probably easier to just go ahead and replace the starter motor and solenoid.
If this does not work, make sure the ignition switch and wiring to the starter is good by checking for voltage from the ignition switch. When your buddy is holding the key in the "Start" position, the small wire going to the starter motor (not the large one from the battery) should energize with 12 Volts DC. This is the signal from the ignition switch. If the small wire doesn't get "hot" when the key is turned to the "Start" position, you're problem is in the ignition switch or wiring to the starter from it.
But I doubt it. It's probably your starter motor and/or solenoid.
Hope this helps.
Monday, April 23rd, 2007 AT 5:44 PM