Good morning all. I have pretty big problem with my fuel system on my 6.9. A few months ago my tank selector valve went bad and I had to drive around for a while on the front tank. A couple days ago I put in a new valve (SMP brand from rockauto). The next day it started pouring fuel from the cap of the front tank and I was driving on the rear tank. Come to find out the fuse for the aux fuel solenoid was blown. So I replaced it and with power on I can hear the solenoid working. This morning however I only put fuel in the rear tank and drove my daughter to school. Got to her school and now I have fuel pouring from the rear tank from the cap.
Does anyone know what would cause the fuel to be backing up and pouring out like that?
This is my daily driver so the sooner anyone can help the better.

 

I had the same problem with my 7.3 idi and I bypassed the valve directly to the front tank. Sounds like fuel tank selector valve is sticking halfway between tanks. (Using fuel from the front tank and putting return fuel in the rear tank making it overflow) I would suspect the valve. Make sure that the fuel lines are hooked up correctly. Hope this is helpful.

 

thanks for the advice. I'm going to double check everything again.
Any idea if there's an aftermarket brand for these valves that's actually reliable? I know the majority of them are cheap junk.

 

My valve was sticking but by flipping the switch every two miles at highway speed seems to have flushed out what ever was hanging up the valve. If you have the old one out you might be able to clear it out with shop air and try reinstalling it? I have read that the wiring colors are not the same as OEM on some valves so take care in wiring as well as fuel/return lines hooked up properly. I can't remember the name of the aftermarket valve that's made by the same company as OEM valves were. Franklin the moderator on the 80-86 forum is familiar with them you might want to post a question over there.

 

I don't know of an aftermarket brand. I was going to replace mine with manual valves, but I don't drive that truck often enough to make it worth it.