What was found
PILOTS REPORTED THAT WHEN THE ELECTRIC FUEL BOOST PUMP WAS RUN THAT THE ENGINE FUEL PRESSURE EXCEEDED REDLINE. AFTER MUCH TROUBLE SHOOTING AND ADJUSTING AND LOOKING FOR RESTRICTION IN THE FUEL SYSTEM, IT WAS DETERMINED THAT THE ENGINE DRIVEN PUMP WAS NOT REGULATING THE OUTPUT PRESSURE WHEN THE ELECTRIC BOOST PUMP AND ENGINE PUMP WERE RUNNING AT THE SAME TIME. FUEL PRESSURE MEASURED AT THE CARBURETOR WAS HIGH. THE ENGINE DRIVEN FUEL PUMP WAS REPLACED AND THE FUEL PRESSURE NO LONGER EXCEEDED RED LINE WHEN THE ENGINE DRIVEN PUMP AND BOOST PUMP RAN AT THE SAME TIME.