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I have a 2001 150hp HPDI with 95hours. The engine sat for several years without constant use, and ethonal fuel in the tank (only about 5 gallons). The fuel tank was drained and cleaned, all fuel lines were replaced, the external fuel water separator was replaced, all fuel filters were drained and replaced, and the VST was removed and cleaned. The screen in the black cylinder was removed and cleaned as well. The local yamaha parts dealer recommended ring cleaner and this "shock" treatment was performed running about 20 gallons of fuel. Once this was completed the spark plugs were changed with NGK.
At this point, the boat would start up, would idle initially until it reached operating temperature, and then would run rough with idle. However, the engine would run fine at WOT, at 3500rpm, at 3,000rpm and at 1500rpm. If you were to shift the throttle into neutral, it would immediately stall and would not restart until the engine has cooled. Then the above could be repeated.
I brought it to a mechanic who claimed to have software and electronic diagnostic tools. He, without hooking up to his computer software, sends off the fuel injectors to be cleaned and flow tested. They came back, put on the injectors, and BAM, same problem existed. Once the boat got to operating temp the engine would not idle. However, now once it stalls, the engine will restart without having to let it cool down.
Now, this engine has some type of technology that when the throttle position is in neutral, it shuts down two cylinders (oh the mechanic threw this part at it instead of trouble shooting it), this didn't fix the idling issue. So the mechanic calls and says he had to order computer soft ware to run diagnostics on this year yamaha (you know, the software I thought he already had). So he tells me that his software is telling him the ECU is bad or the wiring harness is bad so he recommends replacing both; the total cost for these parts are $2800 installed, on top of the $1200 he already threw at it. Now, I am not a part thrower at a problem to fix a problem. Especially when the engine has 95 hours.
I would like to know if someone out there has a way to actually trouble shoot the wiring harness, the ECU, or if this is totally in the wrong direction, and someone has had this very issue, please throw out some ideas.
I ran the boat yesterday at WOT, cruised at 3200 rpm for at least 10 miles, and back down off the throttle. The engine didn't stall immediately as before. But does feel like it is running in reduced cylinders only at 800-1000 RPMs, once you l go above this, the engine runs smoothly. There was a post I saw from a couple years back that discussed properly cleaning a piston and some leaf valves (I wanted to know if this is in the VST or the high pressure fuel pump).
Also, according to the mechanic, he claimed all pressures were within operating specs once he put the cleaned fuel injectors back on. The low pressure was at 50, the high was at 750 or greater, and the belt looks good for the high pressure fuel pump.
Any thoughts would be welcomed at this point. I just don't see a motor that has 95 hours having a bad ECU. What are the causes for this engine operating into the reduced cylinder mode? Is there a sensor that can be over rode to see if this is what is actually happening and why it initially stalls under load?
At this point, the boat would start up, would idle initially until it reached operating temperature, and then would run rough with idle. However, the engine would run fine at WOT, at 3500rpm, at 3,000rpm and at 1500rpm. If you were to shift the throttle into neutral, it would immediately stall and would not restart until the engine has cooled. Then the above could be repeated.
I brought it to a mechanic who claimed to have software and electronic diagnostic tools. He, without hooking up to his computer software, sends off the fuel injectors to be cleaned and flow tested. They came back, put on the injectors, and BAM, same problem existed. Once the boat got to operating temp the engine would not idle. However, now once it stalls, the engine will restart without having to let it cool down.
Now, this engine has some type of technology that when the throttle position is in neutral, it shuts down two cylinders (oh the mechanic threw this part at it instead of trouble shooting it), this didn't fix the idling issue. So the mechanic calls and says he had to order computer soft ware to run diagnostics on this year yamaha (you know, the software I thought he already had). So he tells me that his software is telling him the ECU is bad or the wiring harness is bad so he recommends replacing both; the total cost for these parts are $2800 installed, on top of the $1200 he already threw at it. Now, I am not a part thrower at a problem to fix a problem. Especially when the engine has 95 hours.
I would like to know if someone out there has a way to actually trouble shoot the wiring harness, the ECU, or if this is totally in the wrong direction, and someone has had this very issue, please throw out some ideas.
I ran the boat yesterday at WOT, cruised at 3200 rpm for at least 10 miles, and back down off the throttle. The engine didn't stall immediately as before. But does feel like it is running in reduced cylinders only at 800-1000 RPMs, once you l go above this, the engine runs smoothly. There was a post I saw from a couple years back that discussed properly cleaning a piston and some leaf valves (I wanted to know if this is in the VST or the high pressure fuel pump).
Also, according to the mechanic, he claimed all pressures were within operating specs once he put the cleaned fuel injectors back on. The low pressure was at 50, the high was at 750 or greater, and the belt looks good for the high pressure fuel pump.
Any thoughts would be welcomed at this point. I just don't see a motor that has 95 hours having a bad ECU. What are the causes for this engine operating into the reduced cylinder mode? Is there a sensor that can be over rode to see if this is what is actually happening and why it initially stalls under load?
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