02 yamaha 90 limp mode

engine was staling out at idile so removed carps and cleaned.engine started right up and ran like a top.left the dock to test out got to 4200 rpms and motor went into limp mode 2000 rpms within 5 minutes with no alarm. changed thermostat and tested alarm buzzer ok. engine wasnt hot. tried again 2000rpms again.oil level showing full on tack. any help would be appreciated.

[boats.net]

Test the buzzer by disconnecting wires from temp sensor on head and touch wires togather with key on, buzzer should sound.

i tested the buzzer and it tested ok everything on tack is ok.engine only goes to 2000rpms when i take it out.in neutral rpms goes to 5200 rpms any sugestions thank you.

[boats.net]

Start with a compression test, test ignition while running to see if loosing fire to any cylinder, test fuel system for fuel restictions and make sure each cylinder is getting fuel.

did a compression check all 3 show good commpresion. could a bad senser cause motor to stay in limp mode or something in oil injectors. how do i test ignition to see if everthing is firing. engine runs good end everything looks good

[99yam40]

Check timing on all 3 cylinders with a induction timing light. That should tell you if each cylinder is getting fire to the plug. It will also tell you if the timing is being retarded and into limp mode. I do not know how far the timing is suppose to be set back in limp mode, but it will not be at what the manual says it should be at WOT.
Right now I am having a problem with the timing on a C40TLRX where the Idle timing is 14 ATDC instead of 7 ATDC with linkage adjusted to the manuals specs and I can not get an answer to what will cause that.

Be aware that if you are having fuel issues and you are running lean or oil problems you will hurt the motor if you keep running it