When I start up my B27F and try to drive away without warming it up, it is just flat when I push down on the gas pedal. I have checked the cold start [auxilary air valve] to make sure the disk is closed and it works properly. Checked for air leaks, checked timing, O2 is OK. Have air jets set properly. Runs very smoothly after warmed up. Any suggestions?
Paul Selby
pselby@dtgnet.com
Phil says: I suspect there's a problem with the control pressure regulator (aka: "warm up regulator"). This is not the same as the system pressure regulator built into the fuel distributor; it's a separate unit. I don't know where it's located on a B27/28 (I don't have a V-6 in the driveway to look at), but I'm sure you'll find it. It will be right on the motor somewhere, and there's one electrical connector to it.
The purpose of this device is to lower pressure in the control section of fuel distributor when the car is cold. The control plunger that regulates fuel flow to the injectors works against this controlled fuel pressure -- the lowered pressure permits the plunger to open further for a given amount of airflow, thereby richening the mixture for cold running.
There's an electric heater in the warm up regulator that works just like an electric choke -- when the ignition is turned on, the heater element warms up and gradually lets the fuel pressure increase until a normal mixture is obtained. Because it's mounted on the motor, the regulator stays warm after the ignition is turned off, so you don't get the richening effect again in subsequent starts unless the motor has cooled down.
Since the car tunes properly when warm, you have no apparent vacuum leaks and the disk in the aux air valve opens and closes as advertised, I can't think what else it might be.
Please let us know what you find!
