Andy, In short: The accumulator keeps fuel pressure on the system after the engine has been shut off to make it easier to start when turned back on. Cold or Hot when restarting. Cold start valve /thermal time switch aids in starting cold. Lambda unit along with 02 sensor adjust the air/fuel mixture to help smooth out the engine idle after a couple of minutes. The large swing could be the 02 sensor trying thru the Lambda to correct the mixture. Air vaccum would affect the up and down if not correctly hood up or leaking.A lot of these things work together to ensure a good start and economy in running. The surging could also be the slow correcting of the Idle speed motor /speed ECU unit. Like cleaning off your desk. Track down the problem one at a time and fix it. Or like some do just get a leaf blower. John hervey www.specialtauto.com --- In dmcnews@xxxx, Soma576@xxxx wrote: > Hello guys, > > as a summary, my symptoms are: > 1. hard starting when cold > 2. somewhat hard starting when warm, but MUCH easier > 3. engine dies sometimes even after being warm > 4. RPM's flow from 1000 to 500 when idling. as it approaches 500 every time, > the engine nearly quits but it surges back up like it should. > 5. extremely high fuel pressure - over 100 psi, probably closer to 130 or > greater. > 6. recently had a fuel line leak near the accumulator. i do not know if it > was a hose that connects to it or where exactly it was. i had the car towed > and 'they fixed it'. i had problems starting the day the leak happened. it > could have happened before or after i had trouble. > > do these symptoms or problems have a good relation to what happens when you > have a failed fuel accumulator? i am still trying to figure all of this out. > > thanks as always, > Andy > > > Soma576@xxxx > 1982 DeLorean DMC-12 VIN#11596 > Fargo, ND 58102 > > > [Non-text portions of this message have been removed]