2009 Yamaha F40 Outboard Service Manual, Page 88Get this manual
Troubleshooting the power unit Symptom Fuel not supplied (all cylinders) Refer to page Check the fuel pressure6-4 Clogged filter Check the fuel filter for clog and dirt6-9 Fuel leakage Check the fuel line for leakage6-1 High-pressure fuel pump mal- Check the high-pressure fuel pump oper- 5-22 function ation using the YDISCheck the high-pressure fuel pump 5-22 resistanceMain relay malfunction Check the main relay5-15 Short, open, or loose connec- Check the high-pressure fuel pump input 5-22 tion in high-pressure fuel pump voltagecircuit Check for wiring continuity between the 5-22 high-pressure fuel pump and the main A-3 relayCheck for wiring continuity between the 5-22 high-pressure fuel pump and groundA-3 Fuel pump malfunction Check the fuel pump for leakage6-11 Check the diaphragm for tear6-13 Check the rocker arm7-41 Improper valve timing Check the timing belt7-15 Compression leakage Check the compression pressure7-1 Check the valve for bend or stuck7-33 Check the piston and piston ring for 7-51 damageCheck the cylinder for damage7-51 Intake air passage malfunction Check the ISC valve for stuck5-18 Check the intake manifold and throttle 6-16 body for air leakageCause Checking step