Date registered: Sep 2011
Vehicle: 86 280ge, 87 300 td wagon, 94 sl320
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fuel smell resulting in small explosion
I would like to make this post as I have been chasing this problem for a year now!. One year ago (perhaps longer) the customer complains of a loud bang coming from the engine. I tried and tried to duplicate the problem without any luck. What was happening was the fuel tank gets hot turning the liquid gas into vapors. This expansion that is taking place must go somewhere! The fuel vapor is routed to the activated charcoal canister. It is there that the vapor is stored while the car is sitting in a lot on a hot day. When you start your car the silenoid opens releasing in small incriments the fuel vapor to the intake manifold via a vaccuum line. WELL I had a fuel purge code stored so I decided to research the problem and found that the three lines that are on the end of the canister are: one from the gas tank, one goes into the intake, the third is a vent line which SHOULD have a check valve in it. It is routed into the frame in the left front wheel well and gets the clean vent air from the frame rail located only ONE FOOT FROM THE STARTER A GREAT IGNITION SOURCE!!! When the check valve fails and falls into the frame it will leak fuel vapor resulting in a highly dangerous, highly flamable situation on a hot day. When you go to turn over the engine any brushed motor(the starter motor) will throw sparks(even a brand new starter will spark). So fuel vapor is guided nearly a foot from an ignition source, this seems to be a self destruction feture on the w129 sl!! Good thing the car has full coverage as mercedes fails to produce a line with a check valve as the blueprint shows!! I would plug the line but plugging the line will pull a vaccuum on the fuel tank and on long trips the car will vapor lock, resulting in driveability issues........will update when mercedes figures out what part is missing in their manufacturing or blueprint.......