1996 Seadoo XP "Rev-Limit" at 3800 RPM

[2-Smoke]

I have an interesting but irritating issue with my 1996 Sea Doo XP. The ski starts and idles perfectly both in the water and out of the water, but as soon as you leave the boat ramp, it will hit 3800 rpm and feels like its bouncing off rev limiter. The RPM is always the same. It will however rev out on the trailer. I have been chasing this problem for a few weeks now and I haven't made much headway with it despite changing and testing many of the parts that commonly fail.

The XP had both carbs professionally rebuilt at the end of last season with genuine Mikuni parts from OSD, and it was running perfectly. Now it is having this same issue every time it is taken out on the water this season. All grey fuel lines were replaced already when I bought it.

So far tests and checks I have completed include:
-replaced the fuel selector with a brand new OEM unit
-bypassed fuel filter
-tested rectifier (idle at 13V and 5500RPM at 13.7V)
-tested to see if any A/C voltage is reaching the battery
-Ohm tested ignition coil
-changed sparkplugs
-Ohm tested stator and wires going to rectifier
-trimmed plug leads back 1/4 inch

I did notice when you unplug the battery on the water and put it back on, the ski will do one good pull up to about 6000 rpm and then the issue returns and it right back to 3800 rpm again.

Does anyone have any ideas of what might be causing this issue?

 

[etemplet]

Rev limiter on the MPEM. I had a RFI do the same thing at 4170 RPM. I'd play with the throttle and coax it. One out of 20 times I could get it past 4200 and it would shoot up to 6900 and run great. Soon as I let it drop off below 4000 it had the problem every time. I try swapping MPEMs. Or the CDI. I'm not sure which one has the rev limiter on the XP. Have a buddy with an XP?

I may have a gray box for an XP in my parts pile.

 

[artr]

Rev limiter on the MPEM. I had a RFI do the same thing at 4170 RPM. I'd play with the throttle and coax it. One out of 20 times I could get it past 4200 and it would shoot up to 6900 and run great. Soon as I let it drop off below 4000 it had the problem every time. I try swapping MPEMs. Or the CDI. I'm not sure which one has the rev limiter on the XP. Have a buddy with an XP?

To build on what etemplet has told you, the rev limiter is a function of the CDI module. I do not think there is a reliable way to test that unit except swapping it for a known good unit as he recommended. If you can't easily do that I would check a couple of things. The CDI has 2 connectors going to it. Check that those wires are in good condition and open and check that the connectors are clean and secure. Additionally, the CDI receives 12V from the holder relay that is on the MPEM module. You could remove that relay and temporarily short the 2 connections that relay connects (red/blue stripe and red/purple stripe wires) to rule out if the relay is causing a fluctuation in the 12V while the ski is running. Do that for a test ride but do not leave that connection shorted for a long time when the ski is not running because that will drain the battery.

 

[2strokeboy]

What engine is in the 96 xp

 

[tobytd]

800 2 stroke

 

[etemplet]

To build on what etemplet has told you, the rev limiter is a function of the CDI module. I do not think there is a reliable way to test that unit except swapping it for a known good unit as he recommended. If you can't easily do that I would check a couple of things. The CDI has 2 connectors going to it. Check that those wires are in good condition and open and check that the connectors are clean and secure. Additionally, the CDI receives 12V from the holder relay that is on the MPEM module. You could remove that relay and temporarily short the 2 connections that relay connects (red/blue stripe and red/purple stripe wires) to rule out if the relay is causing a fluctuation in the 12V while the ski is running. Do that for a test ride but do not leave that connection shorted for a long time when the ski is not running because that will drain the battery.

Man you know your shiznit. Good Stuff !!

 

[2strokeboy]

If it has rave valves check them and the solenoid if it has one

 

[2-Smoke]

Thanks guys. I do have a friend with a spare MPEM. I'll try swapping the grey box out and see how it does.