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My boat is slow at 7k rpm than it goes to 6k rpm and is fast + exhaust fumes

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factory81

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Okay so I am cruising and the boat isn't planed. The boat just frankly isn't going that fast. There are excessive amounts of exhaust fumes compared to when we tested it.

We are at 7,000rpm going as fast as we can and I am just guessing but we are doing 25-30mph maybe.

Than the boat (without touching a thing) goes to 6k rpm and starts hauling ass until it becomes too bumpy / too fast and I have to slow it down. Once I slow it down the engine is once again slow at 7000rpm.

Once the boat dropped to 6,000rpm the boat seemed to put out less exhaust fumes.

While we had the boat at 7000rpm and going slow we put out excessive exhaust fumes.

And why does the boat go fast and than slow? Dropping from 7k to 6k.

I couldn't even consider pulling a tuber when it was slow.

This is with 4 riders probably at about 650 pounds total. Whats up with this?

Too much weight?

Why the exhaust fumes though?
 
You are probably experiencing a worn wear ring in the jet pump assembly. Too much clearance between the outer ring and the impeller causes cavitation. This cavitation means you are making foam instead of force.
 
the smoke is a different problem... the high speed screws on the carbs may be set to something other than zero, leading to an overly rich WOT... Better than to lean and seizing the motor though...
 
factory81 said:
How do I fix this? Is this what creates all this smoke / slow speed? Or just one of my problems?
Click to expand...

Probably is your primary propulsion problem.

The exhaust might be a side effect. If you sit in one place with any motorized vehicle at high revs, the exhaust fumes will accumulate faster.

Smoke may be an indication of a oil to fuel mixture problem. But that is not directly related to the high revs and no-go issue.
 
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just look'n at your pics, the return hose on motor, shouldn't be "T'd", way it is, you want constant flow. Take "t" off, and turn other way,..didn't look right, and blown up microfiche shows, way i'm describ'n it..
Have ya gone thru carb/s and raves, yet...?
 
How do I go through the carbs and raves?

I am beginning to think I was just "driving it wrong". My dad is 230-240lbs, I am 160. My dads girlfriend is 150. All in the back row. Another 180lb passenger up front.

We had a ton of weight in the rear and had a hard time planing because my dad wouldn't let me mess with the trim really. So we were cruising at full speed with the trim all the way down (the previous owner of the boat said that you shouldn't ride at capacity with the trim all the way down and at cruising speed..it is harsher on the engine?)

Where does that T hose go? I might need to do some studying here if there are an tutorials. Get some diagrams....

I think that the boat would finally plane and than the engine let out a sigh of relief and dropped down to 6k rpm because it was just that much easier on it?

I am hoping so. Impeller and wear ring dealer installs look like $1000 jobs (if that is the problem)
 
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Raves'.........

Wear ring........it's not often that my opinion differes from another mod, but dont' think your problem is in your wearing ring. If it were, you'd never make the speeds your making.

IF your raves are stuck open, your low range speeds, trying to plane out, would be all but impossible. When you get to plane and start to pick up pressure on the exhaust system, the RAVE's are getting the flows they need to be efficient.........

There is a lot of info on the raves, including the link at the bottom of my signanure titled........"a look inside the 787"....

You can also do a search, using the search engine in the top tool bar of this page and you'll find a lot of info on removing and cleaning the raves....

The other thing conserns me is the amount of oil I see in your hull. It's possible that one or both your RAVE boots are broken, dumping that oil into your hull..............:cheers:
 
Those are pics of the engine before I bought it and cleaned the engine out (with degreaser). The hull is dry, but yes there was some oil that came out when I was washing it out.

I am going to bring a video camera and record video of us on the boat and you guys can judge from that and some recent pictures.

I am going to study as much as I can from the manuals I found and stuff.

The previous owner got the boat with their house and they don't know much but how they took care of it (which was...minimal?, no rebuilds or anything major from what it sounds like).

I was like aw man that sucks if the impeller and wear ring was broken (expensive, and hard for a mechanical noob).

It is odd that my rpms drop from 7k to 6k and we pick up speed.
I am wondering if its the odd weight distribution and heavy load, and the excessive smoke. I have 2 friends that both say that my boat smokes more than it did when we test drove it. It is all coming through the exhaust, not like sitting in the engine bay.

I might change spark plugs because...why not?
 
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Yeah I definitely plan on getting my hands dirty with this boat. So I can learn a few things :)

Going to try and take it out this morning to see if it runs funky with just 1-2 passengers.
 
I looked at one of the spark plugs today and it was pretty black so we are going to get new spark plugs put on.

My dad and I are going to attempt to clean the RAVE's after this weekend, and I am going to continue to dig up any other howto's on getting my Sea-Doo running at its best.

One was definitely in bad shape, and the other could have used replacing also. The bad one was like .03 gapped or more.
 
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A few things

Re the black spark plugs - the only place that matters is the color of the white insulator which holds the lower electrode in place. it should be tan or brown, not black or white soot. All the black on the threads and outer ring, you can ignore. Also the only valid reading has to be obtained at medium to full throttle, then chop the ignition (not the throttle) and pull the plugs out in the water. Its a pain, but idle spark plug readings arent too good.

Replacing the wear rings is not a big deal. http://www.seadoosource.com/wearringremoval.html has a nice writeup on it. it involves a fair amount of disassembly (outside the hull) but its not hard just put the parts on a clean rag in proper order and watch for the little o-rings. Takes about 2 hours for 2 rings. Saves about $ 400.

Working on older sea-doos is very satisfying because you'll find the actual repair is doable and saves you many hundreds of bucks,
 
timmyboy76, which return are you referring to?

In the first pic there's the one on near the plugs, coming out on the top left corner of the head, that should be the flushing intake, it splits to the two flushing ports one on the transom and one near the fuel tank...
 
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