I'm having trouble getting my truck to start. It's a 1976 D-100 with 225 manual trans.
When I turn the ignition to start position and everything works just like it should. The engine turns over but will not "take off" instead,I release the igniting from the start to the run position sometimes the engine will continue to run, other times it won't. I have replaced the ballast resistor, voltage regulator and coil. I don't know where to go from here and was hoping someone here has maybe experienced this before??

Probably a faulty ignition switch or wiring between the ignition switch and the ignition system — I bet you're not getting voltage to the ignition system when the key is in the "start" position. To test this, first make sure the parking brake is on and the transmission is in Neutral. Turn the key to "On" (not "Start"). Then go under the hood and operate the starter by using a screwdriver to connect the two large terminals on the starter relay or the two terminals on the starter itself. If the engine starts and runs, replace your ignition switch and/or repair the wiring.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

try "bump starting" just a light tap of the key a few times to see if it will fire. my old jeep liked to have random ignition switch probs and it always has enough gas to start in those conditions, another reason to bump start it or itll flood, ha. the key in this trick is that most ignition systems have separate circuitry in the start vs run.

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'72 Valiant DD for over a decade-225-Disc brakes, big T-bars, big Sway bars f/r, carter bbd/super six, GM HEI, 2- 12" subs in trunk, 1000w amp...
'77 cherokee cheif widetrack-360-33x12.5 tires-no lift. keeps driveway dry-project/backup DD/mudder

Just noticed your post and your user name.Welcome to the forum hope the boys got you going on the starting problem.I'm 6shotvanner here and SixShot over on the vannin dot com forum,hope I don't get confused I see you're in the AirForce,I'm guessing MountianHome? or commuting across the border to Spokane.Thanks for your service

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83 B-150 slant 6,4 speed. 79 B-300 360 pathfinder 4x4. 74 W-300 318 4x4 git-r-done 80 B-100 sl6,4speed