I'm thinking low pressure fuel pump faulty. Have pump bulb after engine stop.
In fact, they should not be hard.
It would appear that the lift pump is not keeping the VST filled with fuel. Particularly if the motor will continue to run if and when the primer ball is being pumped.
Engine is fuel injected and runs great when under power. Problem only at idle and takes about 3-5 minutes before engine dies.
What kind of pressure am I looking at chief ?
Fuel injected model. No carburetors.
No more than about 5 psi I would imagine. Yamaha does not list a specification for the low pressure pump.
Seems the high pressure pump would have constant pressure being its electric whereas the low pressure is mechanical and if faulty when rps lower it would struggle.
Not yet just trying to get as much info as possible. Back to my recent post if its losing fuel pressure at idle my assumption is that the low pressure pump is faulty because its mechanical the lower the rpm the less it pumps. The high pressure pump is electrical and not dependent on rpms.
Have someone pump the primer ball continuously to keep the VST filled while the motor is running at an idle. Just a squeeze every so often should do. If the motor does not stall, that would further me to repair/replace the low pressure fuel pump. Using the primer ball will do what the pump is supposed to be doing.
Replaced low pressure pump and tps still had problem. Got to thinking as the engine ran great before disconnecting all electrical, hoses and controls in order to run same thru water tight flanges and 2" hose. When disconnecting main harness 10 pin connector which probably had not been apart for 20 years had to really force it apart. Sure enough some of connector pins bent and not seating in female receptacles. So far so good. Thanks for all the input.
I don't quite get what your questioning.
