[urq] Running problems caused by "leaning out" 83 urq.

[John Bird]

The regulated fuel pressure is 1 bar cold and 3.9 bars when hot; when 
the car passes 2.00 bars we get lean out and the car will not run 
without stumbling and spluttering. Mixture is too lean. By disconnecting 
the electrical regulator of the warm up plug, we can extend the driving 
time of the engine before the regulated pressure is too high for the 
engine to run properly. The heat of the engine then comes into play, as 
the ambient temperature will cause the regulator to warm up.

We know that this is not an O2 sensor problem, as the car reached 
running temperature, the ECM is checks out; fuel pressures are OK, 
injectors are new, the sensor plate in the distributor rises and falls 
correctly.

Has anyone any idea why the we would get lean out when we pass 2.00 bars 
of pressure? The car will run fine during the warm up phase of say 2 1/2 
minutes with the connection made to the warm up plug, or 20 minutes with 
it unplugged.

John B.