Been crossing from back to front since I bought it. Recently I've noticed cross flow in both directions. Irritating but not critical. To stop this completely do I have to drop both tanks and replace both pumps? Do aftermarket FDM's have the same tendency for failure?
I want to replace the bed when I find a decent one. Is this condition a safety issue that should light a fire under my *** in doing the job? Hoping to wait till tax return shows up.

 

A bad valve in the rear FDM causes transfer from the front to the rear tank. A bad valve in the front FDM causes transfer to the front tank. So yes, replacing both FDMs is the solution.

Is it a safety issue? Depends on how you manage it. If you allow a tank to overfill it will spill gas out which isn't the greatest thing to do. But if you don't let that happen there's no issue.

 

Thanks. That's pretty much my conclusion as well. In researching the replacement FDM's,the price difference is astounding. A range of 100$ to 500 on Autozone, and from 40$ to 1305$ on Amazon. Considering that I need two, that's potentially more than the truck is worth. Think I'm just going to live with it.