dual fuel tanks

[tech247]

1992 f 250. won't run on rear tank. has new fuel pump. can hear rear pump run but no fuel pressure on fuel gauge. runs fine on front tank. 50 psi.
any ideas.

 

[Skandocious]

Did you replace the sending unit when you replaced the pump?

 

[tech247]

fuel pump

no. transfer old unit. tested level senor before installing pump. gauge sweeps ok. did install new pig tale harness connector for new pump.

 

[surewhynot]

I have heard of the selector valve going bad and letting one pump pump fuel into the other tank instead of the engine.

 

[Skandocious]

I have heard of the selector valve going bad and letting one pump pump fuel into the other tank instead of the engine.

I've also heard of this...

 

[mrfixit]

The selector valve can and does go bad, and that is relatively inexepensive plus easy to change. Also make sure your fuel cap is venting properly. a clogged vent will create a vacuum in the tank, not allowing fuel to leave.
I am not real clear, but I do think there's a possibility that you also have the servo in-tank pumps in addition to the framerail mount one in your truck. I don't have my manuals nearby at the moment. If you do, the rear one may be bad.