At first I thought I managed to miss a shift with a manu-matic. Leaving a gas station a week ago, I had our project 300C in the “shift-it-youself” mode with the traction control off, ready to go play. As I went to shift from first to second the car bucked, acting like it had ran out of fuel, electricity or both and the transmission ignored my command to shift gears. Annoyed, I put the car in automatic mode and went to work on damage control with the wife, who was giving me the glare that indicated that she was not happy with my driving. If it had been one single incident I would’ve written it off as my own stupidity and moved on, but then other things started to happen with the car and all of them seemed connected…one morning, the engine stalled out while driving and the gauges “reset” themselves, idiot lights and all. Then there was the longer-than-normal starts. And finally, on a damn cold night as I was heading home, the car stalled out at a stoplight. I shifted to neutral and re-started the car, moved the shifter to “drive” and…nothing. Absolutely nothing. I had to block traffic while I shut the car down and let the power stay off long enough to let the computer brain-dump what was going on before the car would re-start and move. Once it got moving, it didn’t want to move more than 25 miles an hour and it was bucking and shuddering like a car that was burning the last fumes from the gas tank. A five-minute sit was all it took for the car to stop this temper tantrum and drive normally, so I ran to the parts store and hooked up a code reader. Nothing. Not one code, not even a stored code.

Confused (and irate), the research began. While I was trying to figure out if something electrical had given up the ghost, a Moparts member did a little research and located some information regarding the fuel system. Seems that the 2005-2006 Chrysler LX cars (300C, Magnum and Charger) have had issues involving the Multi-Function Control Valve (MCFV), which among other things functions like a rollover check valve. During the initial design phase of the LX cars, ethanol-infused fuels either were dismissed or weren’t tested as much as they needed to be, and over time the ethanol was absorbed into the float, causing it to swell. This allows raw fuel to be sucked into the charcoal canister and up through the fuel vapor recovery system. When the brakes are hit, the excess fuel gets sucked into the intake, the mixture goes rich, and the computer pulls the plug. This resulted in stalled cars and irritated owners, which led to an NHTSA investigation and Chrysler acted by extending a lifetime warranty on the early LX cars to replace the fuel tank and associated systems, free of charge. (If you want more information on this issue, CLICK HERE)

Which is how I found myself at Martin Dodge in Bowling Green, Kentucky on a cold Tuesday morning, with Angry Grandpa living up to it’s name, bitching and being cantankerous the entire drive in. Parked outside the service doors, it even looked like a pissed-off old man, like one who has to go to a doctor but didn’t want to go in the first place. Check out the photos below and see just what it took to get Grandpa back to his full fury:

The fuel tank is just prior to the rear suspension setup and is a major pain in the ass to remove. Exhaust, driveline, inner fenders and the plastic ares near the jack points have to be removed.

Did I mention that the fuel tank was filled to the freaking brim? I thought I did…sorry, guys. For once, I was more than happy to let someone else wrench on the car. And miraculously, barely any fuel was spilled.

In a nutshell, the rollover valve swelled up and stuck open. The line that sends fuel vapors to the charcoal canister was instead drawing raw fuel up and into the intake. When this happened, the 5.7 would run severely rich, and the ECM would panic and shut everything down. Of course, the line to the charcoal canister was wet with fuel. Bingo.

The fix? A shiny new fuel tank…the MCFV is part of the tank and cannot be serviced separately. Free of charge. Thank you, Chrysler.