Will not run at all when a number 6 fuse is in

I can understand your confusion because that makes no sense. You are saying that when the fuse 6 is removed the vehicle starts and runs properly. Then you put it in and the vehicle does not start?

If this is the case, does the left low beam work with the truck running and the out?

Does the vehicle have day time running lights? If it does, that fuse is for them as well. Since they would come on right away, I'm questioning if there is a ground related issue. Can you tell if the fuel pump is working when the fuse is in?

The only thing I can think of is a ground related issue. Unless, someone has wired things differently. How does the rest of the wiring appear to be?

Let me know.
Joe

He found the problem the people that were working on it before were swapping parts with other vehicles and have the wrong headlight switch and brake light switch wasn't even in it. There is still a lot for him to figure out so if he runs into any more problems he needs help figuring I will be posting.

Sounds great. Unfortunately if he found that then he may find more of that. That is the worst thing to try and figure out because we have no idea what other people did and when they don't do things properly it just makes it a nightmare.

Come back anytime. We are here for what you need. Thanks