S To isolate one weak cylinder short out one bank of cylinders at a time The bank giving the lower readings will include the weak cylinder STARTING CIRCUIT CHECKS See Engine Electrical Section 8 for a description of these checks GENERATING CIRCUIT CHECKS See Engine Electrical Section 8 for a description of generating circuit checks and regulator adjustments IGNITION CIRCUIT CHECKS See Engine Electrical Section 8 for a description of ignition circuit checks FUEL PUMP TESTS If the owner has complained of poor high speed performance the fuel pump may be at fault Too low a pump pressure or volume will cause a high speed miss because of lack of fuel delivered to the carburetors while too high a pressure will cause carburetor flooding Pump Volume Test 1 Disconnect both fuel lines at carburetors plug one line and direct opposite line into a container preferable one indicating the pint level fig 7 16 2 Start engine and run at idle using fuel in carburetor bowl i e Fig 7 16 Fuel Pump Volume Test i 3 Measure the time required to deliver one pint of fuel then shut off engine At idle the pump should deliver one pint of fuel in 45 seconds or less If no gasoline or only a small amount flows from open end of pipe then the fuel line is clogged or the pump is inoperative Before removing pump remove gas cap disconnect both inlet and outlet pipes and blow through them with an air hose to make sure they are clear This will eliminate the possibility of a clogged gas strainer in the fuel tank Reconnect pipes to pump and retest flow If capacity is within limits proceed with Pump Pressure Test below Pump Pressure Test 1 Attach vacuum pressure gauge hose to fuel line fig 7 17 while opposite line remains plugged from above test 2 Operate engine at idle and observe reading on gauge Pressure should be 4 to 5 lbs and should remain constant at all speeds between idle and 1000 rpm If pressure is too low or too high or varies materially at different speeds the pump should be removed for repairs or replacement If the fuel pump checks out correctly on a high speed complaint overhaul the carburetor 3 Remove gauge and plug and reconnect fuel lines to carburetors Inspect fuel lines for kinks and bends and check all connections for leaks s a tc f 3 r L l Fig 7 17 Fu Pump Pressure Test