Mark, I'm sure others can describe it better, but here's my explanation: The fuel accumulator is a reservoir for pressurized fuel. Since the fuel pump is not operating 100% of the time, the accumulator acts to provide a constant source of pressurized fuel to the fuel injection system. When the system working properly, the fuel pump pushes gas into the accumulator, where it is stored under pressure. The outlet of the accumulator feeds the fuel injection system. When the fuel pump is not pumping fuel, the engine is fed from the pressurized accumulator. By the time the supply of fuel in the accumulator is exhausted, the fuel pump should have cycled on again, filling the accumulator again. If the accumulator cannot maintain pressure, you run the risk of the fuel lines to the engine depressurizing when the fuel pump cycles off, which could lead to a hard-starting condition, especially if the engine is hot. (I don't know if "vapor lock" is an appropriate term for a fuel-injected car, but the principle is similar, regardless.) Hope this helps, Scott Gardner -----Original Message----- From: id [mailto:ionicdesign@xxxx] Sent: Wednesday, February 26, 2003 10:14 AM To: dmcnews@xxxxxxxxxxxxxxx Subject: [DML] fuel system question > > i have a stupid question and i should know this but what does a Fuel > Accumulator do exactly? > > mark