I've done a lot of research here and other places and I think I have an issue with my dual function fuel reservoir.
However, I didn't see my problem specifically so hopefully someone here can help me out a little.
I have a 1989 F150 with the 302 and an auto. It's the long bed and has dual tanks.
As long as I've had it, the gauge for the front has never worked, but the back has, despite that, I always use the front tank and just keep a couple of gallons in the back incase I run out.
The other day when I went to fill up the front tank, the pump kept shutting off like the tank was full, even though it wasn't. I tried a different pump and even a different gas station but the problem persisted.
So I filled up the back tank and drove away. I noticed that the gauge was dropping super fast, but figured it was just a sensor error.
THen, while driving, I smelled gas really badly and when I looked, gas was POURING out of the front tank!
I switched to the front tank and drove like that home with no issues.
Now the truck seems to sputter when I give it gas while running on the back tank, but it idles just fine. It still sends gas spilling out the front filler cap though.
The front tank doesn't have much gas in it either it doesn't seem like (gauge doesn't work so I'm not sure).
I know now that my dual function fuel reservoir is likely the culprit, but I don't get my I can't fill the front tank.
I wouldn't have a problem only keeping one tank and just capping off the other one. It's my daily driver and only means of transpiration right now so I need a fix ASAP, for cheap too (broke college kid lol)
Any help would be greatly appreciated!
Thanks in advance!!
Josh

 

If fuel pours out the filler / cap then that tank is full of fuel. No other explanation for that.
A bad DFR can pump fuel from one tank to the other. You could have multiple issues such as plugged fuel lines, plugged filter etc.
See link in my signature for some fuel system troubleshooting.

 

The check valve in the front low pressure pump is bad. Instead of the fuel returning to the back tank its returning to the front. Sounds like its time to replace the front pump. By the way you need to be in the 87-96 fourm.

 

Thanks for the link klricks, I'll check it out. Jrh5610, I thought my truck didn't had a check valve? I thought that came a little later. That's for the reply, and yeah I posted this in the correct area righ after I realized that I put this in the wrong place.

 

I could be wrong on that forgot that those had the selector valve so you might want to check it out.