1998 Buick Century 3.1M
The complaint is long crank time on a start, black smoke once started and stalling at low engine speeds.
Where would you start?
Pull the vacuum hose from the pressure regulator and look for signs of fuel. There should be no sign of fuel at the vacuum port. If there is fuel the regulator is bad and extra fuel is being pulled into the engine.
The MIL is also on so trouble codes should be checked. If caused by the fuel problem they can be cleared after the repair.
P0172 indicates a rich fuel condition
P0300 indicates rough engine running
P1133 indicates too little activity from the O2 sensor
All those were probably set by the fuel problem but we should watch the O2 activity after the repair to verify the sensor is good.
That is about as easy as it gets.
Kenneth Hayes
