Have and FD791D on a Turf Tiger. Engine cranks but wont start. Will start with starter fluid. All voltages at ECU are correct. Fuel pump pressure correct, all relays working. . No error codes.Grounds are good.Fuel pressure sensor and regulator good. Any Ideas or suggestions ?/ Thanks
I know nothing about this system. I'll have a guess that the pressure/vacuum sensor is not sending a signal to the ECU, therefore fuel won't be supplied, once you spray starter fluid in, it fires, the speed increases enough to make the vacuum sensor work enough and fuel is then supplied.
Check vacuum sensor hose/seal for kinks, cracks, tightness etc. It may not throw a code if the sensor is OK, if it's not getting the vacuum signal it's not sending the "go" signal. Take all this with a grain of salt.
Fuel pump is working, safety switches by passed. Will start with starter fluid but then dies. Injectors are not firing.. preformed test and keeps saying to replace ECU. Switched ECU with another mower, no change. Hooked light to injector leads, doesnt flicker when engine is cranked. Got me stumped !!
Look at the white wire in the ecu on your machine harness I would say it is corroded up. If so about the best way to get it going is a new wiring harness
I just looked back and seen where you said the fuel pump was working I misread that. Sorry there are two relays close by the ecu or on the battery side if not look under close by the radiator check those by changing them and see if something stops working or if makes any changes
Look at the white wire in the ecu on your machine harness I would say it is corroded up. If so about the best way to get it going is a new wiring harness
I just looked back and seen where you said the fuel pump was working I misread that. Sorry there are two relays close by the ecu or on the battery side if not look under close by the radiator check those by changing them and see if something stops working or if makes any changes
Already changed relays. injectors test good. just wont fire. Have 12v on white wire to injectors and good at ECU. The issue is like crank sensor not working . Too bad this engine doesn't have one!
#11
Hammermechanicman
Have you checked that the air pressure sensor is changing voltage when the engine cranks? Sounds like you have an ecu input problem. If you have checked the injectors and swapped the ecu that pretty much leaves an input to the ecu not working. Check the wiring connections to the sensors.
Had one today doing the same thing with low compression adjusted valves then compression cane up and then wouldn't start because of fuel line was blocked
Okay what you got is the DFI system and instead of crank position sensor it is using a speed sensory system. IF the Op would like a copy of the SM I send a link via PM to the one that I can temporary upload to my Google drive.
You will a fuel pressure of 25.6 ± 0.7 psi. Also speed sensor may not sending the signal to ECU. Hint the speed sensor is part of ignition coil kill circuit.
Back to the FD791D. Replaced coils , { thanks for the info} engine now starts but runs rough. Disco the . Vacuum Pressure Sensor, engine runs much better, replaced pressure switch and vacuum tube, same problem. Any ideas!!
