I have a 94 F150 with a 302, 140k miles. The truck used to fire up with a tap of the key, now it has to be cranked anywhere from 3-5 seconds. It seems to help if I bump the ignition a few times, then it won't crank and it fires up like it used to. It runs completely fine, seems like the idle is getting a little rough though. Changed the plugs, fuel filter, battery. I don't think it's a fuel issue because it does it randomly hot or cold on either fuel tank and even after priming the pump by cycling the key a few times. Any advice would be helpful, don't feel like replacing a starter, thanks..

 

Why would you replace the starter?
It has nothing to do with your issue.

Sounds like you may have a bad check valve in one of the FDM or the FPR is not seating all the way.

 

Any way to diagnose? I know there's an issue with the check valve in the rear tank, it always pumps to the front.

 

Then you have a bad check valve in the front and not the back.
Maybe your whole problem.

 

Even though it has the issue no matter what tank I have it on?

 

It should run OK on the front tank and poor on the rear tank unless the rear tank also fills while on the front tank.

But anyway you have a problem with the front FDM and you need it fixed.

 

Ya the starting issue is on either tank, runs fine, I don't use the back one very much