Boat won't go above 4000rpm??

[Mitch_Pelletier]

1997 Challenger Single Engine Rotax

I tried my boat out tonight, first time since fixing the throttle butterfly on one of the carbs à few days ago. (it was stuck and I freed it up, reinstalled everything same as before) Boat was working real well before this.

Started and ran good. I ran for about 10mins in the warer, good acceleration , good planing.

I then stopped, shut the engine off and the engine compartment was full of steam. Looked like water was boiling?

I was only about 5 mins at idle from the dock.

I went back to the marina, pulled the engine cover and saw that a small water line, about 1/4" dia connected to the muffler was disconnected. Probably from my foot when I was working in the engine compartment.

I reconnected, started back up, no more steam. Took the boat back out, but couldn't get past 4000rpm, and couldn't hit the powerband. It does sound a bit "different" than before.

It starts good, doesn't really bog down or hesitate but stoos at 4000rpm

I took it home, changed the plugs with other used ones I had, started it, works ok. But on the trailer with the hose, it hits the rev limiter, as it normally does, and can't really tell if it's cured.

Could this be just a plug issue? Or something more serious? I'm gonna put new plugs tomorrow and try it back.

 

[Mitch_Pelletier]

Also, now that I think about it, the engine bay was filled with white smoke, didn't smell like anything. It also looks like there might be a leak in the rubber connector between the tuned pipe and straight pile? I tried to see but looks like on the bottom of this rubber connector.

Could an exhaust leak like this cause lack of power?

Oh, and my plugs were super black, oily, did not smell like gas.

 

[Mitch_Pelletier]

Solved... I think.

Looks like culprit was the rubber connector between the tuned pipe and final exhaust.

Had a little issue where it slipped off, but retighened and should be good. Plugs look great. More testing tomorrow.

 

[POPPS]

No!,,,,you need to replace that hose,,,it is fried,,,when there is a break in that hose,,exhaust gases fill the hull,,,and choke the engine,,,sometimes,,,the piston will seize,,,that 1/4 line goes to the front pipe,,,

 

[Mitch_Pelletier]

Thanks for the note back.

I replaced that (2in?) hose from the picture above, took the boat out and after 20mins of running, the brand new hose split in the middle!!

What is causing this to fail?

 

[POPPS]

You have a cooling issue, If you have an air pistol,,remove every hose and blast air thru all your cooling connections,,including the small 1/4 line that attaches to fittings at the front of the pipe,,,then attach the garden hose,,,look for obvious leaks,,,check that the air bleed/pisser is working..,also with the water running,,,check under the front pipe to see if the frost/die plug is leaking.

 

[fatblockabody]

Your water regulator is failing or plugged (or the 1/4 lines that feed it are plugged on one side or the other)

Regardless, your is getting very hot. Water is not making it to the tuned pipe inlet (follow the long hose from the RAVE looking thing on the muffler to the 1/4" barb fitting on the tuned pipe).

 

[Mitch_Pelletier]

Ohhh... I found my hose from the water regulator to the top of the tuned pipe was burnt and chewed! Replaced. All works good.

Except I have a leak in the valve. I will do some more checking.

 

[fatblockabody]

Ohhh... I found my hose from the water regulator to the top of the tuned pipe was burnt and chewed! Replaced. All works good.

Except I have a leak in the valve. I will do some more checking.

The housings like to swell over time. If it is leaking out the port in the housing the bellow is cracked and/or it is leaking back up through. On the stem there is what looks like an o'ring gland. I have fixed that issue by replacing the bellow/diaphragm and placing an o-ring on that gland.

That being said, these things can be finicky and it will only get worse with time as more and more of these things swell/dry out, etc. If I could find a RPM window switch that worked for 2 strokes I would wire that up to control a solenoid and electronically control the water injection on all my 787s that. I know EWCI's exist, just kind of tough to find used ones anymore and I think it could be simplified.

 

[Mitch_Pelletier]

Looks like my bellows is good, so probably leaking back up through.

I will try and find an o-ring and try that out.

Should that 'bolt' going through the center of the diaphragm be tight??

 

[fatblockabody]

Looks like my bellows is good, so probably leaking back up through.

I will try and find an o-ring and try that out.

Should that 'bolt' going through the center of the diaphragm be tight??

The adjuster? There is a certain number of turns backed off from tight it is supposed to be. If you search around on the forums you'll find it