Bouncing off rev limiter

[gmpisawesome]

2008 Yamaha Waverunner deluxe. Here’s what I’ve done to it:
New Yamaha wear ring
New solas 14/20 dynafly (it is TIGHT; within spec for clearance on wear ring)
New solas intake grate
Filled the pump shoe with flex seal
Resealed ride plate, intake, etc
New fuel pump
New fuel injectors
New spark plugs

now the issue. When I pin this thing, it will almost immediately hit the rev limiter. From stop it will go for 1 second without it , but if I go WOT it will hit that rev limiter pretty much no matter how fast I’m going. Trim makes little difference. It seems like anything above 75 throttle it hits that limiter. I can do 45mph on it, and with the 75 throttle it gets good traction from what I can tell. I’m at a loss here! Where else can there be cavitation? Is this an engine issue?

 

[OCD Solutions]

What pitch was the stock impeller?

 

[Quinc]

did you install the pump seal the correct direction? and did you use silicone?

 

[gmpisawesome]

What pitch was the stock impeller?

If im honest, i do not know. But on the stock impeller/wear ring it was doing the same thing. That was why I replaced them but to no avail.

 

[gmpisawesome]

did you install the pump seal the correct direction? and did you use silicone?

Pump seal? If thats the pump shoe then it should be. There was a felt strip that ran the length of the pump shoe, which I removed and replaced with a hefty line of silicone. All underside parts were siliconed.

 

[OCD Solutions]

What RPM is the gauge indicating when you are on the limiter?
That model seems to have an RPM limiting feature, any chance you are using the learner key or somehow triggering the Low RPM mode?

Additional Features​

• Multi-function Electronic Information Center: Provides the operator a quick read on speed, RPM, fuel level, low fuel warning, low oil pressure warning, overheat warning, hour meter, check engine light with self diagnostic function.
• Industry's First Remote Controlled Transmitter: With the touch of a button on Yamaha's innovative remote-controlled transmitter, you can activate and deactivate the VX digital security system and Low RPM Mode from up to 30 feet away.
• Low RPM Mode™: Also with the touch of a button on the remote transmitter, the top speed of the VX Deluxe is reduced by nearly 30 percent.

 

[gmpisawesome]

What RPM is the gauge indicating when you are on the limiter?
That model seems to have an RPM limiting feature, any chance you are using the learner key or somehow triggering the Low RPM mode?

Additional Features​

• Multi-function Electronic Information Center: Provides the operator a quick read on speed, RPM, fuel level, low fuel warning, low oil pressure warning, overheat warning, hour meter, check engine light with self diagnostic function.
• Industry's First Remote Controlled Transmitter: With the touch of a button on Yamaha's innovative remote-controlled transmitter, you can activate and deactivate the VX digital security system and Low RPM Mode from up to 30 feet away.
• Low RPM Mode™: Also with the touch of a button on the remote transmitter, the top speed of the VX Deluxe is reduced by nearly 30 percent.

Thats a good thought, but its not on low rpm. its actually maxing out its rpm. I've been thinking; could the seal between the engine and the impeller shaft be letting air in?

 

[fx1mark]

Thats a good thought, but its not on low rpm. its actually maxing out its rpm. I've been thinking; could the seal between the engine and the impeller shaft be letting air in?

It could. If it was me I would inspect everything that you worked on closely for something wrong. Pull your ride plate and in the dark shine a flashlight inside the pump and look for light leaks.

 

[gmpisawesome]

It could. If it was me I would inspect everything that you worked on closely for something wrong. Pull your ride plate and in the dark shine a flashlight inside the pump and look for light leaks.

okay, so I did this and there's no cracks. What about this theory; I've noticed a little bit of water in the hull when I'm underway. obviously the vacuum bulge pulls out it so I never notice it. But, could that midshaft bearing be allowing air to leak past when a large pressure differential is created? There also looks to be a hole on top for grease, but mine doesn't have a grease fitting on the end but is instead vented to atmosphere. Im thinking if i throw some silicone around the midshaft sealing area and plug that air allowance, it might help. Any guides on pulling the midshaft bearing look to include pulling the engine, and well, ill just deal with it if that's the case.

 

[fx1mark]

okay, so I did this and there's no cracks. What about this theory; I've noticed a little bit of water in the hull when I'm underway. obviously the vacuum bulge pulls out it so I never notice it. But, could that midshaft bearing be allowing air to leak past when a large pressure differential is created? There also looks to be a hole on top for grease, but mine doesn't have a grease fitting on the end but is instead vented to atmosphere. Im thinking if i throw some silicone around the midshaft sealing area and plug that air allowance, it might help. Any guides on pulling the midshaft bearing look to include pulling the engine, and well, ill just deal with it if that's the case.

It would be the seals that would leak. I would think a visual inspection would be good enough the rule out a leak. Also the midshaft needs to be properly sealed to the bulkhead. There is also an O-ring in the center of the coupler. This is a great thread on midshafts. https://www.x-h2o.com/threads/midshaft-talk-building-rebuilding-sn-vs-rn-etc.105232/#js-post-1212770

 

[gmpisawesome]

The Grease is applied via the Black Hose.

The Zerk Grease Fitting is at the Hose end with the Metal Bracket.

If yours is missing the Zerk fitting then screw a new one in.

The Engine needs to be moved forward to remove the Midshaft.

Yeah, ill probably do that. Thank you for the name of it, I was having a hard time finding the name. I will do that and see if there's any improvement, as it looks like there is a spring-loaded ball acting as a valve. Again not sure this would be causing cavitation, but with how many items I've already replaced chasing this, I'm grasping at straws.

 

[gmpisawesome]

It would be the seals that would leak. I would think a visual inspection would be good enough the rule out a leak. Also the midshaft needs to be properly sealed to the bulkhead. This is a great thread on midshafts. https://www.x-h2o.com/threads/midshaft-talk-building-rebuilding-sn-vs-rn-etc.105232/#js-post-1212770

Yes I did see that! I looked through the post but mine visually looks alright. Im really hoping I don't have to pull that engine forward, as that's probably a ton of work to do.

 

[fx1mark]

Yes I did see that! I looked through the post but mine visually looks alright. Im really hoping I don't have to pull that engine forward, as that's probably a ton of work to do.

No, moving the engine forward is pretty easy. The hardest part is removing part of the exhaust. If you have a pipe then you just remove the chamber. Unbolt the motor and and pull the fuel lines and you can scoot the motor forward enough to remove the midshaft.

 

[gmpisawesome]

No, moving the engine forward is pretty easy. The hardest part is removing part of the exhaust. If you have a pipe then you just remove the chamber. Unbolt the motor and and pull the fuel lines and you can scoot the motor forward enough to remove the midshaft.

Oh, word. I think my plan of action will be to put grease into that bearing, see if I can find a leak, and go from there. Thank you very much for your help, super helpful.

 

[fx1mark]

Oh, word. I think my plan of action will be to put grease into that bearing, see if I can find a leak, and go from there. Thank you very much for your help, super helpful.

The bearing in the midhsaft housing is sealed. When you pump grease into the fitting you are greasing the seals and shaft not the bearing. Be carefull, if you pump in too much grease you can blow out a seal.

 

[gmpisawesome]

The bearing in the midhsaft housing is sealed. When you pump grease into the fitting you are greasing the seals and shaft not the bearing. Be carefull, if you pump in too much grease you can blow out a seal.

10/4. I plan to use marine grease through a syringe as to not overcompress is.

 

[OCD Solutions]

Any updates?

 

[gmpisawesome]

Any updates?

Not yet; been a little cold as of late. Ive sealed around the main bearing, but was not able to remove the grease fitting as the dang thing seemed welded on with how hard it was to turn off. Im going to try my best to fill it using a syringe to not overpack it, but I've gotta think air escaping through this fitting is what could be causing it, especially, if there's no grease standing in the way. Action plan still fill with syringe and clamp off the fitting to prevent air.