Seadoo challenger 1800 engine runs very rough

[tommy1976]

Hi there:

On my 1998 Seadoo Challenger 1800 - one engine runs very smooth and has lots of power while the other one doesn't run very well at all and seems to lack power.

Some observations:
i. Compression checked on both cylinders and are in the 150 range
ii. Engine only starts with choke and won't idle under 1000 - just stalls out. When I apply gas to bring the revs up it seems to stall out as well makes a muffled sound
iii. By applying a combination of throttle/choke I can get the RPMs up to 3000 but its very inconsistent and that is only on the hose or stantionary. When I get the boat into the lake it just has no power

Spark plugs, 2 cycle oil and gas is brand new and not contaminated and the second engine runs fine.

My thinking is this is a problem with the carburators. I was planning on removing them and cleaning them tomorow, but ahead of that I just wanted to get some insight if it can be anything else.

Many thanks in advance for all your helpful advise.

 

[seadooya]

clean the raves as well, make surethe excel pump on back carb, is floating freely and squirting.

 

[tommy1976]

clean the raves as well, make surethe excel pump on back carb, is floating freely and squirting.

I just finished reading "Section 6 - Fuel System" in the manual. Is this as complicated as they make it sounds or is pulling and cleaning the carbs a big deal on these boats? Specifically - is it difficult to properly adjusting them again when you're done?

I'm comfortable rebuilding carbs for snow blowers and garden tractors but reading the service manual this sounds super complicated...wondering if this is worth trying myself or should I take it into a dealership to get cleaned up...

 

[seadooya]

dealership wont "overhaul" them. It'll sit in the shop/yard, for a few days, then they'll spray wd-40 on them, make'm perty, then say, your good to go. You'll get out there, it'll fall on its face, you'll bring it back, and then they'll say, you need a new motor.

Carbs take about 30 minutes to pull. Its in a boat, you got crapload of room to work. No need for rebuild kit, just remove them, then break apart, one side a time, clean all passages, then re-assemble. Nut'n to it, bud.

 

[tommy1976]

dealership wont "overhaul" them. It'll sit in the shop/yard, for a few days, then they'll spray wd-40 on them, make'm perty, then say, your good to go. You'll get out there, it'll fall on its face, you'll bring it back, and then they'll say, you need a new motor.

Carbs take about 30 minutes to pull. Its in a boat, you got crapload of room to work. No need for rebuild kit, just remove them, then break apart, one side a time, clean all passages, then re-assemble. Nut'n to it, bud.

SHould I leave the adjusting screws / needle valves as-is - or should they be pulled out too to clean them?

I'm not concerned about cleaning - just wondering how difficult it will be to adjust it once its all back in place. THe graph on the first page on how to adjust this beast is very intimidating

 

[seadooya]

you'll see a black cap on the hsa screrws, remove it, then turn clockwise to bottom it out, if it turns at all. Count the turns. Do that as well, with the lsa (looks like a "T" adjuster), bottom it out, counting the turns, so then, when removed, you know how many turns. Think ur set-up is 1-1/2 turns, low, 0 on mag carb, 1/4-1/2 on pto(back) carb.