90LTRZ vibration when trying to plane

[dpfundst]

Hi,

Have a 2 stroke 90Hp Yam 90LTRZ 20001. Runs great, but just now (and several other times) when heading home after being out on the beach all day, the engine starts up great, runs great at low RPMS but when I go to "hit it" and get on plane I get a vibration strong enough for me to back the throttle down to 2000RPMS.
Going out this morning, didnt have the problem, and it seems after recalling that it only has happened after sitting while we hang out on the beach for the day. Not on the way out.
This is intermittent, but seems to only happen when coming home after a day at the beach.
One thing I do in the morning is start the engine in the driveway prior to heading to boat ramp.
Any ideas?
Much appreciation
Dwight

 

[99yam40]

Re: 90LTRZ vibration when trying to plane

Have you checked the alarm system to see if it is working?
Sounds like temp problem and you are not getting buzzer

 

[dpfundst]

Re: 90LTRZ vibration when trying to plane

do u mean the overheat alarm?
It is working, a had an issue with a clogged impeller and the alarm went off....so I don't think that is it.....but thanks

Dwight

 

[99yam40]

Re: 90LTRZ vibration when trying to plane

Check the plugs, I have seen a leaking head gasket cause plug to get wet and miss fire after warmed up and restarted.

 

[dpfundst]

Re: 90LTRZ vibration when trying to plane

Check the plugs, I have seen a leaking head gasket cause plug to get wet and miss fire after warmed up and restarted.

I just checked plugs, look ok...
by "wet" you mean?

 

[Homosassa]

Re: 90LTRZ vibration when trying to plane

I have the same motor and what seems to be the same problem. Runs great going out but after shut down to fish, can only idle back. Seems to really labor when you give it more throtle. When it first happened, it seemed to correct itself after some time. Now when it happens it does not go away, or at least untill the next time out.
It runs so well on the way out I am reluctant to think it is something internal to the motor or even the carbs. I was directed by some great people on this forum to check for fuel leaks, etc.
I am convinced it had to be fuel related. Either lack of or bad fuel (water). I changed fuel lines, primer bulbs, checked vents, changed plugs, added fuel treatments, and nothing. I did not change the Racor fuel/water seperator because I did not see any water in the bowl. Problem persists.
Changed the Racor filter and after the first shake down run all seemed well. Ran fine after several stops. Then took it out again, and although it took longer to get on plane (I thought I had too many on board and the extra weight may have something to do with it) Got caught in major thunderstorm, bilge was out, took on much water and headed for the dock. Dropped most of the passengers off and headed for home dock. Still could not get on plane but the motor was not bogging down like before, more like a spun prop, although this was freshly reconditioned.
The motor just failed a short way from dock and could not get it started again. Noticed much water in new Racor bowl, so I am attributing it to that.
I am going to drain tank and start from scratch, although I think the problem may have been corrected with the new Racor. Still convinced it's fuel related. I hope this helps, make sure you post when you solve your problem.

 

[dpfundst]

Re: 90LTRZ vibration when trying to plane

I have the same motor and what seems to be the same problem. Runs great going out but after shut down to fish, can only idle back. Seems to really labor when you give it more throtle. When it first happened, it seemed to correct itself after some time. Now when it happens it does not go away, or at least untill the next time out.
It runs so well on the way out I am reluctant to think it is something internal to the motor or even the carbs. I was directed by some great people on this forum to check for fuel leaks, etc.
I am convinced it had to be fuel related. Either lack of or bad fuel (water). I changed fuel lines, primer bulbs, checked vents, changed plugs, added fuel treatments, and nothing. I did not change the Racor fuel/water seperator because I did not see any water in the bowl. Problem persists.
Changed the Racor filter and after the first shake down run all seemed well. Ran fine after several stops. Then took it out again, and although it took longer to get on plane (I thought I had too many on board and the extra weight may have something to do with it) Got caught in major thunderstorm, bilge was out, took on much water and headed for the dock. Dropped most of the passengers off and headed for home dock. Still could not get on plane but the motor was not bogging down like before, more like a spun prop, although this was freshly reconditioned.
The motor just failed a short way from dock and could not get it started again. Noticed much water in new Racor bowl, so I am attributing it to that.
I am going to drain tank and start from scratch, although I think the problem may have been corrected with the new Racor. Still convinced it's fuel related. I hope this helps, make sure you post when you solve your problem.

I have new fuel tank, lines, water separator
Sounds similar problem.........going back out today, I'll post results..
One thing I do before going out is I run the engine with rabbit ear hose attachment so that it starts up smoothy at my busy ramp........most of the day the boat sits at the beach and we just leave to go home, and we get that problem...today I am going to start the boat up before we head back in and let it warm up a bit (like morning runs) and see if that makes any difference...
I will report back

 

[dpfundst]

Re: 90LTRZ vibration when trying to plane

Same thing happened today, we just came back in.
This morning, boat started right up on muffs in driveway, went to ramp, headed out, boat ran great on plane 4200 rpm 30 mph.........left boat on beach for an hour, went to go fish.....boat started right up....went to head out, when trying to plane anything over 2000rpm big vibration, big enough to throttle back down.....ran the boat at 2000rpm rest of day, including come back home to ramp............

 

[99yam40]

Re: 90LTRZ vibration when trying to plane

You need to be careful if it is a cylinder leaning out from lack of fuel it will hurt a piston if you run it that way.

Could be a ignition problem ,but you may need to check while missing is happening to find it

 

[dpfundst]

Re: 90LTRZ vibration when trying to plane

FUEL FUEL FUEL!!!!!

Forgot to mention I was running on less than 1/8 tank of gas during this problem.............Tuesday I added fuel to make about 3/4 tank, and problem went away......topped it off a bit up to full tank and yesterday again no problem...multiple stops and starts....ran great ..engine was not getting fuel

I believe I did not have enough fuel in the tank to have enough pressure to get gas to the engine....it would run fine first time out because I'd prime the system by squeezing bulb....
Low fuel.......not enough fuel to feed engine.
That's 2 days straight without the issue, and I didnt have the issue earlier this year when I had a near full tank...............
__________________

 

[robert graham]

Re: 90LTRZ vibration when trying to plane

Maybe that fuel in the tank was stale, contaminated, water, etc. and when you filled it up the quality was back to more fresh standards?

 

[dpfundst]

Re: 90LTRZ vibration when trying to plane

Had the same problem again..........vibration when trying to plane, after engine warm....
Had plenty of gas, so it was no that.
I brought it to my marine mechanic.

They did a water test and used meters, to recreate the issue, and told me that the oil sender had failed. Once the engine senses not enough oil, it goes into "slow down" mode and will not go above 2000rpm to prevent engine damage. The fact my alarm also failed compounded troubleshooting the
issue.

I got the boat back yesterday.

Took the boat out today.
Mechanic replaced the oil sender, and the alarm as both had failed.

I went out for 2 hours and tried to recreate the problem, but I couldn't, because it's fixed!
Actually running better than ever.

It was a "great day" to test her out, raining on and off, windy and choppy, but it's always a beautiful day when your boat is running smoothly at 4500 rpm and 38 mph.............woo hoo!