2012 80hp 4 stroke wont rev out

[Jordanhack]

At breaking point. I have now had to limp home 3 times now with the same problem. Run out to the reef is fine but at some point the boat starts running rough like a fuel problem and wont run much above 3000rpm. Come home had injectors cleaned twice, vst cleaned out, all filters, tanks and fuel lines replaced. Motor comes good after each time but then take it out and same problem. Already thrown $1500 hundred at this and had enough. Any thing i or the mechanics are missing?

[pstephens46]

At breaking point. I have now had to limp home 3 times now with the same problem. Run out to the reef is fine but at some point the boat starts running rough like a fuel problem and wont run much above 3000rpm. Come home had injectors cleaned twice, vst cleaned out, all filters, tanks and fuel lines replaced. Motor comes good after each time but then take it out and same problem. Already thrown $1500 hundred at this and had enough. Any thing i or the mechanics are missing?

All the previous cleaning made an improvement? Ran good for a period of time then failed again? Has the fuel tank been cleaned? Edit- you mentioned tank cleaning.

[Jordanhack]

Yeah mate done everything. Posting for a mate and apparently it revs out at 2600.rpm every time. Is that potentially a limp mode?

[pstephens46]

Yeah mate done everything. Posting for a mate and apparently it revs out at 2600.rpm every time. Is that potentially a limp mode?

You would get an alarm for limp mode. So it ran better for a time after each cleaning? Did he try pumping the primer ball when the issue is happening?

[boscoe99]

If it is believed to be fuel related then have your mechanic temporarily install a pressure gauge on the high pressure fuel line. Monitor the fuel pressure when the motor is running normally. Make a note of the varies pressures seen at various RPM's. Then when the motor starts acting up take a look at the fuel pressure gauge again. Are the fuel pressures the same as when the motor was running well, or are they different?

[panasonic]

Does the alarm work? Been tested?

[robert graham]

Is there a fuel water seperater type filter on the motor?

[Jordanhack]

Thanks for all the replies guys. Yes the motor has run better after the cleaning for about an hour then wont go past 2600rpm even when squeezing primer bulb. Motor stays that way running very rough until the cleaning again. No alarm. Alarm has not been tested. Could be worth doing. He has a brand new fuel water separator installed. Is there a certain revs the motor will run at if in limp mode? I will talk to the mechanic regarding a fuel pressure guage fitted. Any other ideas

[99yam40]

does this motor have gauges hooked up to it so that you can see indicators if a problem shows up?

the alarm system needs to be tested to make sure it functions properly

[Jordanhack]

The motor has the guages hooked up but i have also had the diagnostic computer on it when it was sick. No faults shown at all

[99yam40]

well if the gauges are working properly and even the diagnostic software does not show a fault while the problem is occurring, it is time to rule out too low or too high of fuel pressure as the problem.

Strange the cleaning fixes it each time but for only a short time.

have the injectors been flow and spray pattern checked before and after the cleaning to see if there is a problem with one or more of them each time?

[pstephens46]

Pull the safety lanyard and try to crank motor. Alarm should sound immediately.

You could run the motor off of a portable gas can with clean fuel. If that helps then you could point to contamination. Certainly reads as if that is the issue.

[99yam40]

If contamination is the problem,
you need to find out what is getting plugged up
and then where is the stuff that is plugging things up coming from.

Does just cleaning the injectors help, or does just cleaning the VST help.
doing it all at once does not tell you what helps to solve the problem

[zenoahphobic]

Just adding, if the motor runs fine for a while after "cleaning" then it begs the question what is being cleaned out; the contents in the cleaning fluid, rags whatever, should be thoroughly examined to see what the contamination is. There seems to be a cycle here.

[zenoahphobic]

But I suspect the engine is overheating seizing, limp mode or not. Easy to miss the obvious, have you tried stopping the engine and let it cool for the period that you would have spent cleaning, but don't do anything, then try running it again. What happens?
Go look behind the thermastat housing for build up of of salt and crud. Your thermastat itself maybe faulty. Is your tell tale healthy, when was water pump done? Worth a look there.
Sorry you're getting the usual answers here. There is a faulty human expectation that by doing the same thing over and over again, that somehow we expect a different result.