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Stop The Drool - Wrangler Fuel Tank Replacement

Posted in How To on April 1, 2013
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We’ve heard a lot of “horror” stories about Wranglers not taking fuel at the pump, and we thought they were just that, stories. Until our ’06 Unlimited started regurgitating a little fuel at every fill up. Or call it drooling fuel if you want. What would happen was we’d go to the pump, start filling the Jeep, lock the pump on with the catch on the handle, and walk away. Then when the tank was full, the pump would click off, and we’d replace the nozzle and the gas cap and leave. Well, after five years and 100,000 miles of doing it that way, one day the Jeep spit some fuel out. We figured it was just an over-eager pump and didn’t worry about it. In fact we didn’t worry about it for a year, we just got adept at listening for when it was getting near full, and clicking the pump off ahead of time.

We got to where we’d be able to beat it about half of the time. But over a year or so, that’s a lot of spilled fuel. Our flares started fading real bad and we could see it was eating into the paint too. We checked that none of the vent lines were clogged, collapsed, or crimped. We checked that the fuel filler wasn’t crimped or obstructed. Nope. Unlike many of our Jeeps, this one was relatively stock and we knew that no one had messed with any fuel lines. Once we determined there was no easy solution, we went to the experts at GenRight Off Road.

We suspected the problem was somehow in the gas tank itself, but after describing the problem and the steps we went through another possibility arose. GenRight posited that at some point in the Jeep’s life the tank might have been overfilled, forcing fuel into the charcoal (or EVAP) canister which is mounted close to the fuel tank and low in the back corner. You can overfill these Jeeps by continuing to put fuel in them after the first click on the pump nozzle. Once the fuel is in the canister, it does screwy things with the venting of the tank. But, we knew that never happened, and at the time the evap can (PN 52059630AB) was only available at the dealership and was close to $200.

To the left is the factory ’05-‘06 tank. To the right is the much larger GenRight tank. The two valves on the top of the GenRight tank are called rollover valves. The factory tank has a rollover valve and what is called a Control Valve with Integral Fuel management. Hmmm, that’s a new one…maybe it’s not controlling fuel anymore? Anyway, note the factory tank has no fuel breather like Jeeps have had for decades. You can thank the EPA for that one, but more on that later.

So we were looking at the likelihood of their being some internal fuel tank issue. We spoke to our dealership and while there was no TSB (Technical Service Bulletin) for our ’06, there was one for the ’07 and ’08 models (TSB 14-003-12). That TSB fixes the problem by installing a new fuel filler hose with a flapper door or one-way-valve in it. We have no doubt that solves the issue for the JKs, but we worried about doing the same thing in our LJ. What if that wasn’t the problem? Then we’d just be masking the true issue. It is possible to use a GM filler neck (PN 15131046) and modify it to fit a TJ or LJ. But, to our thinking, if the valve in the filler stops an overflow of fuel, where does it go from there? Our low-mounted evap cannister?

We were convinced the problem was in the tank, and now we were determined to find out exactly what it was. However, to do that we would have to cut our tank up for the tankopsy. Which meant we’d need a new tank. Why put a used tank in, when that could have the same problem? So we used this as a great excuse to put in the 31.5-gallon Safari tank from GenRight Off Road. So follow along as we pump up our fuel capacity and cut up a few gas tanks, all in the name of truth, knowledge, and the Jp way.

Problems and solutions
Problem: Fuel sloshes out of the filler before the fuel pump shuts off.

• Check evaporative system hoses for kinks or obstructions

• Check filler neck for obstructions

• Check evaporative canister for fuel

• Replace filler neck with the one-way valve GM neck

• Replace tank with huge bash-proof GenRight tank

Problem: Fuel goes into tank very slowly

Cause: As you put fuel into the tank, it displaces air. That air needs to go somewhere hence the vent on the earlier tank. Later ones still vent but do so in conjunction with the evaporative system.

• Check evaporative system hoses for kinks or obstructions

• Check filler neck for obstructions

• Check evaporative canister for fuel

• If you haven’t found the problem at this point do not just put an open element filter in the vent line. Keep looking.

The fix
For our Jeep, the GenRight tank fixed the problem. Fuel isn’t just gasoline, there are lots of additives in it. The additives change based on your geographic location, the time of year, and federal and state regulations. Just like the fuel we can buy today is different than the leaded gas of the ‘70s, so too is it different than the fuel we could buy just 10 or fewer years ago when these Jeeps were new. We suspect the sticky fill valve was letting fuel come back out of the filler.

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Gen-Right Off Road

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