Ignition issue

[GetItMuddy]

Alright fellas,
Im rusty on old school electronics so I could use a hand here....

I had an issue a few days ago...driving along in second gear (Standard shift) and she cuts off on me. Pulled to the side of the road and found a body ground broke. Fixed that, no issues for a couple of days. This morning, same thing except that the battery ground was loose (Clamp style post lug on it). Fixed that, she fired up. No issue.
This afternoon at lunch, Jumped in, Fired her up, put her in gear and went to take off and she dies. YES, I gave her enough gas to go....
Pushed in the clutch, turned her over and she wouldn't start.
Checked ALL grounds. No issues. Re-worked the battery ground and tried again. No start.
Noticed loose wiring on the solenoid. Re-worked those and she wouldn't even turn over. I could hear the fuel pump but the starter wouldn't even kick. Threw her in neutral, turned the key to "on", jumped post to post on the solenoid and she fired like she never had an issue...
What is my problem here? Key switch? Key switch push rod? (<--My thought) Some electronic doohickie?
Help me out fellas. My brain is toast and I aint had near enough beer....or any for that matter.

 

[adsm08]

Ignition switch is my first though, since it tends to die.

There is another possible issue. From the switch there are two wires heading to the ignition module. One to power it in run, one for start. They meet and splice together somewhere (not sure of the physical location) and run to only one wire at the module itself. A break in that splice can cause a crank/no-start when using the key, but have it fire off fine when jumping the relay posts. I went round and round with and issue like that on my 87 a few years back. I narrowed it down to a wiring issue and then swapped out my complete dash and engine harnesses from a parts truck I had.

 

[GetItMuddy]

Thanks AD. Ill check it out

 

[RonD]

Yes, there are a couple of things you can do to narrow down the cause.

I don't think the '88's had a Power Distribution Box(fuse panel in engine bay).
The battery+ connects to the starter relay, there will be several other wires connected to that same post, that is the power distribution for the truck, all the 12v devices connect there.
Remove and clean all connections on that post.

There should be at least 4 grounds
Battery to Engine(big cable for starter motor and alternator ground)
Battery to Rad support(head light ground)
Engine(head) to Firewall(computer and cab electrics ground)
Engine to Frame(lighting and some times fuel pump ground)

A ground passes power just like 12v connection does, any time you have power passing thru a connection exposed to air it will corrode, it may take 30 years or it may take 30 days but it will corrode, wet corrodes faster that dry, more amps corrodes faster than less amps, but they all corrode, pesky laws of physics in an oxygen atmosphere.
So best to remove and clean these connections now and then.

The quick dieing while driving does sound like spark stopped, but with fuel injection if the fuel pump stops engine will just die as well.

I would get a can of quick start(ether), if the crank but no start happens again I would pull off the PCV hose(or power booster hose) on the intake and spray some ether into intake then replace hose.
Crank engine, if it fires up then dies you have a fuel supply issue.
If it just cranks, no firing, then it is for sure spark issue