89 GMC 2500 5.7 liter fuel injected 5-speed

Sounds funny I know. My buddy's farm truck was having issues running a few weeks ago. He was saying it wouldn't run good or not start at all when it was wet or cold. He dug around a bit and I told him to replace the coil. Here's the thing, it used to crank over but not start, we replaced the coil but it still wouldn't start from cranking. We dug around a bit more and really were scratching our heads. Distributor cab and rotor are newish, that wasn't it. In between then and yesterday he told me that it stopped cranking when the key was turned but him and his dad "bump started" it and it ran perfect. Starter is NEW (not rebuilt) a year ago, plenty of power coming from a newish battery. Ignition module is also new.

Only thing we could think of was a bad clutch safety switch or an ignition switch? Thoughts? I told him to cross the wires on the clutch safety switch and try it but haven't heard back yet. Any help would be great!

Just because a starter is new, doesn't mean it's good. I've had bad starters right out of the box.

That is a possibility I suppose. I'll admit I'm a bit stumped, I'm betting it's something stupid. We have narrowed it down to spark so it is not a fuel or air problem. I'm beginning to think that after all the cranking he did trying to start it, he may have fried the starter.

Planning on tackling this thing again on Saturday as it is the first day either of us have the time. I suppose if I cross the connectors on the starter I'll be able to either take it out of the equation or call it one of the problems. I hope it's not the starter because if I recall correctly it was a pain in the butt to get out the first time.

When the ignition switch is in crank mode it kills all other loads until you let off on the key. The radio goes dead, for example, while cranking. I have seen switches kill the ignition as well, so no start. The only job the starter has is to physically roll the motor over. If it will do that, you can rule out the starter and solenoid, clutch bypass, etc. You need fuel and fire. My 1st money is on a faulty switch that kills the ignition spark while cranking. Maybe the newer stuff is different, but this was quite common back in the 80's and 90's. You can run a wire direct from the battery to the lead, (battery terminal), on the HEI distributor cap to tell. That makes your distributor live, bypassing the switch, and anything else in the way.

[This message has been edited by weaselbeak (edited 11-16-2012).]

Well, revisiting this. Starter was indeed fried, got that replaced and the thing fired right up and ran perfect. Few days after that it started running rough again and then finally wouldn't start even when pull started.

The more I think of it, I really think it's the ignition switch. May try running a lead right to the distributor cap, sounds like a good idea.

quote Originally posted by Monkeyman: Just because a starter is new, doesn't mean it's good. I've had bad starters right out of the box.

I just replaced one under that situation ^^^^^^^^^^^^^^^^^^^^^^^ in my Fiero. I went with a gear reduction starter for a bigger engine and haven't had an issue since.