1996 challenger cutting off

[zperez2012]

Hey guys new to the forum . Recently got a 96 challenger with the 787 rotax . Seemed to run like a top , it has been oil injection deleted as well. Well I took it out on the water this weekend and had some problems . I was cruising through the no wake zone in the river and once I got to the main stretch I got on it wide open . Boat got up to around 44 just cruising then out of no where started cutting out and bogging down . Ended up getting towed back to the boat ramp because it wouldn’t start up. Pulled the plugs and they were oil/gas covered . I mix it at 40:1 and had just put fresh gas and plugs in it . I did use synthetic blend two stroke oil and not the brp yellow bottle . Could this be the problem . I’ve done some research and I think maybe the low speed or high speed on the carbs are too rich and maybe rave valves need cleaning . What really has me confused is when I got home I did a compression test (harbor freight gauge ) and both cylinders were low but even 105 psi on each . Put the plugs back in and it fired and reverse great ? Any advice welcome thanks

 

[mikidymac]

Get a second and better gauge. The Harbor Freight ones are known to be junk and typically read 20-30 psi low.

You need to run only full synthetic API-TC rated oil.

If your compression is actually that low there is your problem. IF the compression is good it's a carb issue.

 

[zperez2012]

Okay will do . What would you recommend, something like a Bosch gauge from the auto parts store ? It’s just got me confused how it would run so good then big out while I was at WOT. Any other things to check , going to clean the carbs today just to see

 

[mikidymac]

I just use the $50 actron one from Autozone.

 

[zperez2012]

Update : compression is good . Pulled the rave valves just to see and they were not only filthy but assembled incorrectly. One was even missing o-rings and the plastic inside was melted . Do you think this could cause some noticeable problems? I’m ordering a new rebuilt set because one was beat up in the groves past repair

 

[mikidymac]

I would still suspect a fuel issue but that isn't good about the RAVES.

 

[zperez2012]

Fuel issue as in too much or not enough ? It was definitely getting too much based off my plugs . Put fresh gas in just waiting on the rebuild kit for the raves. I’m going to check the grounds too maybe

 

[mejim707]

As @mikidymac said, get a good compression tester. I got one from Autozone as well. Ground your plugs wires, remove both spark plugs, open throttle all the way and hit the started for a few seconds to get your top pressure. 105 is pretty low and would result in difficulty even starting in water as well as other issues.

This does sound like a very rich condition. If the carbs run rich, at high speeds the cylinders could potentially load up and cause hesitation followed by a stall. If it stalls at that point you likely won't get it started again.

Have you tried starting it since getting back home? Does it start and seemingly run right? When was the last time the carbs were rebuilt?

A black wet condition on your plugs suggests a very rich condition. You want a tan color on the plugs after use like that.

You may need to pull the carbs. It's not difficult.

If you don't know the last time the carbs were rebuilt it may be a good idea to rebuild them. It's easy. You could also check the below chart for your factory low and high speed settings. Gently bottom out your low speed jet screw. MAKE SURE TO NOTE THE NUMBER OF ROTATIONS! Cross reference the chart for your model. Do the same for the high speed. Typically, unless there are other issues with your ski, the factory settings are best. If your settings are different it may be a good idea to set them to factory suggested and adjust if needed. Remember that any time you adjust the LS and HS you should verify your idle. 1500RPM in the water and 3000 out.

Please someone correct me if any of this info is incorrect.

Carb Specs: Sea Doo PWC Carburetor Reference

 

[zperez2012]

Update : pulled the carbs and cleaned them they were very clean inside and all the diaphragms and gaskets were like new and functional. But both low speed and high speed circuits were turned way out (rich)so I turned them back in to the factory spec. Idle is 1500 and 3000 in and out of water . Yes once it stalled it wouldn’t fire back up but as soon as I got back home it fired up first try . Still waiting on the rebuild kit for the rave valves though so can’t test it fully until then

 

[zperez2012]

It runs perfect in the yard , revs clean and idle great but under a load is when it died. Hopefully cleaning the carbs and resetting them will fix the condition

 

[mejim707]

Yeah, if the LS and HS were that far off it could have definitely been loading up with fuel and that would prevent it from starting after a stall. Just make sure to set the carb to the correct spec. Your boat is the same as mine. Your carbs should be set to LS: 1, HS 0.

When you had the carbs pulled apart, did you inspect the needles? As mentioned from others on the forum it's always a good idea to replace the needles and seats when doing a rebuild. The tips could form a small groove and cause fuel to slip buy flooding the cylinders. If you're inspecting brass the seats, there's a rubber gasket around the bottom. Ethanol in the fuel can cause premature breakdown of the gaskets and fuel could potentially leak past that gasket as well.

It sounds like you're very close.

You can also reference the links below;
The Seadoo Carb Rebuild Thread
Carburetor Adjustments