2004 150 HPDI not firing on 3 cylinders

[boscoe99]

yeah, I may not have explained all the symptoms correctly regarding the ground. it sounds like you are saying its a constant ground, not intermittent that I described above. I probably was looking at some other posts and got confused. yes, mine is a 2.6L model Z150TXRC.

People read stuff all of the time about how a particular Yamaha works and assume that their Yamaha must work the same way. Even some Yamaha mechanics fall into this trap.

It is a terrible assumption to make. Wastes time and money and leads to aggravation.

If there are four different ways to make a motor work, then Yamaha is going to use at least eight.

And then worst of all, Yamaha fails to provide a detailed theory of operation in the service manual for a specific model. What does what and when, and what are the consequences when what is supposed to work does not, and how does it show itself.

Pity the poor Yamaha mechanic. He has no guidelines to follow and no clear trouble shooting procedures that he can use. He is on his own in most cases.

It is almost as if Yamaha has the expectation that none of their stuff will fail and they therefore don't need to provide maintenance and trouble shooting data. Honda is getting into the aviation business. Yamaha better stay out. Yamaha could develop a well crafted airplane but the FAA would never approve it because the data would be so shitty.

[rodbolt17]

actually, its quite simple if you know what system you have and a small amount of general training in electronics.

most all the systems were around for many years in various automotive/military use.

however the average backyardigan cant tell me if its not SPARKING on 3cyl OR not INJECTING on 3 cyl.

for that matter most techs cant either.

all they can really say is 3 cyl don't make any change when they stupidly pull a plug wire on an ECU con*****ed system.

[mm331456]

Yeah, I don’t mean to waste time here, the spark issue is no longer. I think the dealer may have adjusted the TPS (smoke and mirrors) and now we are getting spark to all cylinders, however the fuel pump ground issue has surfaced. The motor is now running when we take the ECU ground that normally goes to the fuel pump (not sure which pump) and ground it to the engine block. Maybe the ECU is bad wreaking havoc on the fuel pump. I think we have the wiring diagram for that particular motor so I will let them know to check the blue wire as suggested by robolt and work our way back. If everything checks out its probably the ECU. If we grounded the fuel pump to the engine block or temporarily ran it that way could it cause issues?