Hi all, first post.

I have read a million different posts across the internet and none really get to my problem, so sorry if you have heard all this before.

I bought a 92 F350 with a 460. The truck is awesome and runs great, but only on the front tank. When I put it on the rear tank, it will run good for a (short) time, then it spits, sputters, lurches (on occasion), misfires (on occasion), feels like it is struggling to move etc.

The fuel pump was bad so I replaced it, didn't solve these issues, but it still runs much better with the new pump. I replaced the seal on the vapor valve, no luck. The 20 amp fuse is good, the fuel relay is good, so, at a minimum, that leaves testing the inertia switch and the tank switch. I think I can rule out the inertia switch because the relay and the tank switch are getting power and both pumps work. The only other obvious thing is the tank switch. Can I just jump the leads to try to get that rear tank to work? If so, which leads would those be because I don't have a wiring diagram?

I know there is more involved with this system and any help would be greatly appreciated. It is super frustrating trying to run stuff like this down.

Thanks

 

The first thing you should do is check your fuel pressure from both the front and the rear tanks. Just because there is a new pump in the rear tank doesn't mean it's a good one. I looked but couldn't find what your fuel pressure should be.

 

The new pump being bad did come to mind, but I know that bad switches, shorts etc can also cause low power to the pump, which would lead to low pressure too. So, before I get into dropping the tank again to replace the pump (which is what I would do if the pressure was low) I want to rule out those other things first.

I have another pump, if I could lift the bed rather than drop the tank I would change it out regardless, but dropping that tank in the yard is a real drag, which I would like to avoid if I can.