[fieldeffectt]

Hey friends,

Ive been in the process of resurrecting a 2005 Monster 620 after its been sitting in a garage for 5 years. Picked it up a few days ago with 9k miles. All maintenance has been done, I cleaned the fuel injectors, fluids changed, brakes bled, clutch fluid bled, filters changed, spark plugs changed etc etc.

The tank was pretty gross and the fuel turned to tar. the bottom half of the tank was nasty, I changed the fuel pump and the fuel filter. When I go to start the bike, the motor cranks, it fires for about a second and then continues to crank. I had a thought that maybe there isn't enough pressure in the fuel line so I crimped the return line going to the pressure regulator side of the fuel tank thinking maybe that regulator is not holding pressure. Lo and behold the motor turn on for a good 4-5 seconds idling. But then turned off. I then realized that I hear the fuel pump turn on and prime when I turn the key to the on position, but then i don't actually hear it turning on when the motor is running. What might be causing this? I have the tank tilted up so i can put my ear right by the underside of the fuel tank to hear if its running or not. Fuel pump is brand new, just swapped it in.

I should also mention that (The fuel pump assembly "flange" does not have wires going to the thermistor, but the only issue i see arising from that is having the fuel light remaining on. Those wires were gunked up and essentially fell off by themselves) However the wires going to the fuel pump all look good.)

Any ideas?

Thanks in advance!

 

[belter]

if the rotation sensor is faulty the ecu doesn't know the engine is turning over, so it doesn't turn the fuel pump/injectors/coils on when you're cranking. given the pump runs when the key is turned on it means all that other stuff is ok as such.

 

[fieldeffectt]

if the rotation sensor is faulty the ecu doesn't know the engine is turning over, so it doesn't turn the fuel pump/injectors/coils on when you're cranking. given the pump runs when the key is turned on it means all that other stuff is ok as such.

Thanks for the reply! So that sensor would cause both injectors and coils not to fire? I check and I have spark coming to both coils when the motor is cranking and it does start briefly for a second.

 

[belter]

the sensor would cause the ecu to activate nothing. it's the ecu doing the doing.

i would certainly check its resistance. i had one last week that was injecting, but not sparking. had 300k ohms resistance, should have 0.8k or so.

it's one thing to check, certainly not the only possibility.