Help;

I have a 96 F150 4.9 dual tanks with 130,00. Last week had a check engine light, Advance Auto read codes lean on banks 1 & 2. After complete tune up plugs, wires, cap & rotor, pcv, air and fuel filter, and cleaned MAF, I reset the light. After driving about 60 miles Check Engine back on same codes. Replaced all O2 sensors and reset light. After about 70 miles light on again. Switched tanks and reset light. It's been about 400 miles and no light but smelled raw fuel on two occasions. Woke up this morning and found a puddle of raw gas under right front of truck. The black canister mounted next to the battery is full of raw fuel and leaking at the top.
A friend recommended this site and from what I've seen it is a great site. Any suggestions, thanks in advance.

 

Hi and welcome to FTE

I'm not sure, but it sounds like you may have a bad switching valve and one tank is pumping into the other causing it to overfill and push gas out of the vent tube into the charcoal canister.
Jimmy

 

Lxman1,

Would'nt that cuase my fuel gauge to read full? According to the gauge I'm using gas.

 

The fuel level remains constant in the rear tank. If it was transfering the fuel it should drop right? I was wondering if maybe the fuel pressure regulator is going out. Since the check engine light comes on while rear tank is being used and shows a lean condition. There is no light while using the front tank but my gas mileage dropped about 4 mpg and there is raw fuel reaching the cannister. Also shouldn't the fuel in the cannister return to the tank?

Thanks Greg

 

The canister is to collect vapors, not liquid fuel. Maybe the tank just go overfilled.
To check the regulator, pull off the vacuum line, if you get any fuel out of it, then it is bad. It is possible that if it is bad, that vacuum is sucking fuel into the system and it is possibly getting into the canister that way.
Jimmy

 

LX your diagnosis was right bad switching valve on the rear tank pump. I rechecked the fuel level this time it was full. Should have been around 3/4 of a tank. I replaced the fuel pump and truck is runnig fine again, mileage has also returned to normal.

Thanks Greg

 

Glad to help. We are here to please.
Jimmy