yamaha 0x66 shut down

[Blue197320]

my motor is an 01 0x66 225. it has 3 new oem lp pumps, the injectors were just cleaned ultrasonically. has a new tp sensor installed. no water in fuel. the high pressure pump did seize up but i was able to free it up soaking it in fuel injector cleaner.

the boat will start and idle perfect all day. when it gets on plane around 3.5k to 4k rpm it will cruise there for a minute or two then just shut off like the lanyard was pulled. it will not build fuel pressure again unless you cycle the key off and back on. the mechanic and i water tested the boat with a fuel pressure gauge and test light. the fuel pressure is at 0 when the motor shuts off and he says ground is lost after the pressure falls. he says hes never seen this before. he determined high pressure pump based on the way it just looses pressure and given that it had seized before. i put a new oem yamaha pump and new vst screen in and water test the boat today. same exact thing happening. plane out to 4k and after 2 minutes shut off again. i have the factory manual and tested the inline high pressure pump resistor which is in line with the blue (negative) pump wire. spec is .53 to .57 ohm. it varies on my dvom from .5 up to .7 ohms. i was not able to check the resistance while the boat was running. i need this boat fixed asap, fishing tournament coming up and paid entry fee already. please help!!

[hugo]

hey blue, look in your manuel and see if any of the safty fetures shut down fuel on your engine in case of a problem. you say your losing ground and dropping fuel pressure,,, were is the ground coming from? is it ECM controlled? or is it simple system ground?

[Blue197320]

i beleive ground is controlled thru the ecu. im going to put it in the water again later and use a jumper to a known good ground and see it the problem persists. if it does not shut off then ill try to replace the in line resistor. its sittin the sun right now with the cowl off and i checked the resistance again and its higher than before so im thinking that as it heats up it just has too much resistance for the circuit. since the resistance varies on the meter and does go up past the spec to me that component tests bad.

[hugo]

not sure about that, havent seen a schematic to see how it is supposed to work. ECU controls ground you need to read and see what parameters it needs to allow ground, then see if those are all in order. maybe theirs another problem that the ecu is trying to protect itself from. i would not just add a ground untill your sure everthing else is ok.

[Blue197320]

on another forum a reputible source stated at more than 5.2 amps the ecu will open the ground circuit. the source also said using a known good ground and by-passing the fail safe wont hurt anything. so the plan is to make a test harness to go from the ground side of the pump to a known good ground with a atc fuse holder in the middle with a 5 amp fuse. also with that i will be able to put my dvom in place and see what amps the pump draws. then after that im going to have another harness that will include the inline resistor that i will be able to check the actual amps being drawn. hopefully i will be able to determine if when the resistor gets hot and amp draw rises and there is my problem.

[hugo]

sounds good, let us now how it goes.

[Blue197320]

well i blew a steering hose coming out of the channel. this is on hold until i fix that.

[hugo]

that realy sucks, sorry to hear it.

[jorgeinmiami]

Better in the channel than offshore while at the tourny
Hope you find the problem

[eggsuckindog]

always sumthin