Starting problem with an 87 D100, please help!
 

I recently purchased an 87 D100. It was running and driving fine, then one day i got home from work, went inside, then went to turn the key and it would just crank, after a while it started and when i went in reverse it jerked a lot and died. After that it would just crank. So I kept cranking every few minutes and it started clicking, so i figure ok it's the starter. I got a new starter it did the same thing, so I got another, what do you know it did the same thing! Then it started to act like it was trying to crank, like it had a bad battery, and would go reeeeal slow, then i changed the starter relay and it started clicking again. I have a good battery, good starter, new starter relay, all good fuses, I'm stumped. I just put a full tank in and reeeally wish I could drive it, so if anybody could help me out that would be amazing!

does the truck have stock or aftermarket battery terminals? if it has aftermarket battery terminals the wire inside the terminal may be corroded and cause the starter to not get the power it needs.

They're not the originals no, I will sure check on that thanks sir.

How's the spark?

The battery may be good but just needs a charge. Will it turn over if you jump it?

No it will not, it does the same thing. Battery is fully charged, could it be the distributor? Maybe the gear locked up or? The flywheel turns but its pretty hard to turn it.

A distributor doesn't stop an engine from turning over. If you can rotate it manually the starter should be able to turn it. If the starter and battery are OK and the starter just clicks there is a problem with connections or wires that is not allowing enough amperage to get to the starter or not providing a good enough ground. Try jumping it again with the positive jumper cable attached to the starters large lug instead of the battery positive terminal and the negative jumper attached to a metal pert if the starter or bolts.

I will try that today, what if it still doesnt?

You must understand that from what you have told us you have two separate problems. You have a starting problem and a running problem. The first thing is to get the engine to turn over with the starter and then find/fix the run problem. You might try unloading the engine by pulling the plugs and see if it will turn over freely. If it does put the plugs back in one at a time and see when it stops turning freely with the starter to try to isolate the problem.

Same truck Same issue?
 

I do not have a running issue with mine (i think) it ran great parked it overnight and now it wont start. I have changed the starter and tested the battery. It turns over like a dead battery (real slow) even when jumping. I jumped directly to the starter with no improvment. If this issue was resolved in your truck I would love to know how. Any suggestion would be great thank you.