Water regulator valve

[Pacer]

98 XPL How can the water regulator valve cause the engine not to run at full rpm? How can you test for this or fix it?

[Bryan Glynn]

It is supposed to shut off at high RPM allowing unrestricted exhaust flow. It injects water to give more low-end torque. If it does not shut off (leak in the bellows, failing housing/spring) then you cannot reach or maintain top RPM because there is too much water in the exhaust.

[Bill O'Neal]

The water regulator is a mechanical water injection system. It works the same as an electricaly controlled water injection system (ECWI).
It injects some of the water that comes through it into the mid pipe at low rpm. Once the pump builds up enough water pressure, it diverts all of the water into the muffler, and the exhaust system becomes a "dry system".

To test it, you tie the ski to the trailer and back it into the water. Disconnect the hose that goes from the regulator to the headpipe on the exhaust system. Using the tachometer to note when the water shuts off, gradually raise the rpm ( building water pressure ) until it shuts off. If it does not completely shut off, a loss in maximum rpm will occur when you ride the boat on the lake. The actual shut off rpm varies amongst different skis and different prop nozzel combinations. The important thing is that it does shut off the water completely.

I usually just remove the seat and ride the boat if it is a two or three seater and view the regualator at WOT. If it leaks water onto the outside of the muffler, it is bad and needs to be repaired or replaced. An XPL is tougher, as the muffler is in the rear, but you can do this same test on the trailer if the pump is in the water.

Bad water regulators are not always fixable, unless it is just that the diaphram came off and the clamp is loose. They usually require replacing the whole unit.

[thomas]

Couple of questions about this old post.
I tied my XPL to my trailer and did the experiment. The water did not shut off at high rpms. 1) What rpms is the water regulator supposed to shut off the water at? 2) And if it is indeed bad and I replace it, are my carb jetting specs now suspect? That is, all my tuning has been done with this water regulator and I could only get to 6900 rpms.

[Technical Support]

It doesn't effect mixture, and it shuts down around 4000 RPM.

[Bill O'Neal]

It never shuts completely off. It only reduces the amount of water delivered to the pipe.

[lbrider]

Re: Water regulator valve

i think i'm gonna try this out on my boat, is it a fairly noticable point where the water starts restricting? if the flow doesn't stop completely, roughly what fraction keeps flowing above 4000? more/less than half?