95 Sportster losing power before planing

[Kenner73]

Hi,
Just got the 95 sportster (single 80hp engine) last month. Original Oil Injenction still intact. Sometimes it runs great, other times, it repeats a distinct problem.

When trying to plane out, the engine acts fine until about half throttle. Cannot get enough power to plane. Sometimes, if patient, and I pump the throttle a little, it will get to plane and then run fine. And SOMETIMES, (maybe coincidence), the engine runs fine once I open the hood and fresh air gets into the engine bay.

Any ideas?
One person thought its getting too much gas or not enough air.
What's the fix?

thanks in advance

 

[seadoosnipe]

Welcome!

Kenner, welcome to the Seadoo forum. Glad to have you here, just not under these circumstances. Let's see what can be done.
You don't mention any troubleshooting you may have already done but we'll just start at ground zero. With an engine that old, I'd like to know what your compression is. Then, I'd like to know if you checked your fuel strainers.
The problem almost sounds like it's RAVE valve related but since the 657cc doesn't have them, I'll have to second guess that your carbs are in need of either cleaning or a complete overhaul. Before doing that, it may be a good idea to see if they're syncronized with each other first, because this could also slow you down.
Reason to think it's in the carbs is because you say sometimes it runs great and other times it doesn't. If it were in the setup, it would do it all the time. Check the fuel filters in the carbs too.........
I havn't read through the 95 manual but I have the 96. Some of this info may not be applicable to your year. But it would be nice to get your compression. If your not sure how to do that, re-post and we'll get you more info on that.

 

[kustomkarl]

Couple things to check

Kenner welcome to the forum. Something else that is basic is the fuel strainer/ filter, you should have a look at too. It just might be dirty, and how old is the fuel your runnng...has the doo been sitting for a while? Did you do the basics before you ran it? Change the plugs, new fuel, clean the gunk from the sparkarester screen over the carbs? With a jet boat that age it probably needs a little TLC just to get it in good running shape. Check these points seadoosnipe and I mentioned and give us a re-post it you still have problems. There are lot of helpful members here that are eager to help you get you boat running in tip top shape. If you don't have any manual resources you could also join as a premium member, and download an operators manual and a shop manual for reference. It has great info on carbs, troubleshooting, diagrams and how too articles that I find very helpful with any problems I encounter. Click on the link at the top of the page under "seadoo manuals" for more details. It's not free, but it is well worth the small fee the forum charges as you can read it on line or download it for your own personal use.
If you have any more question ask away, I'm sure you'll get a quick response.
Karl :cheers:

 

[Dennis]

Losing Power

Welcome Kenner,

Another thing you need to look for is any kind of exhaust leak.
Exhaust gases in the engine compartment will rob the engine of air and cause it to bog down. This would explain your "hood open" and it runs better.
Let us know,

DAWG

 

[Kenner73]

Did the overhaul...still same

Hi,

Thanks for the replies. First thing, when I got the boat, I hired a mechanic to look. He rebuilt the carb. He found that the compression was like 150 I think. And sometimes it runs absolutely fine.

How would I test for the exhaust leak? I don't notice any smoke our exhaust smell in the engine bay.

Should I mess with the High Speed Mixture Screw? One person mentioned to me that they thought that the mixture was too rich as the power loss and smoke behind happened when I was trying to plane out. (although it idles fine).

thanks,

Ken

 

[seadoosnipe]

High speed screw!

No, the high speed screw is pre-set and shouldn't be messed with under normal conditions.
The smoke can be coming from a few places. First guess would be the rotary shaft seals. Depends on how bad it's smoking and how much oil your using.
There's a pressure test you do on the engine for finding the leaks. You'll need a hand held pump system. You got one? I'll see if I can get you the test pressures and procedures if you want to do them.....

 

[Kenner73]

getting closer

I took the boat out today again and water tested the engine.

First run went beautiful. Full power. Don't think I'll mess with any of the adjustment screws.

A few hundred yards out into the bay, I slowed to idle and punched it again. This time, it sputtered and tried, but wouldn't plane out. The engine doesn't choke out, but just holds at a medium rpm and struggles. The RPMs sound the same at half throttle and full throttle when this happens.

I ruled out the lack of air thing. Doesn't really matter if the hatch is open or not. Was just coincidence before.

So....sometimes the engine has power. Sometimes it does not.

We removed the plugs. They were black, but not gunked up. The fuel filter looked fine (that's the cup that unscrews right above the gas tank and has a little screen cylinder, right?)

So, still a mystery.

ideas?

 

[kustomkarl]

Kenner When you slowed to an idle and punched it, did the rpm's stay at around 3000-3500rpms? If it did you rev limiter might be sticking. It is a mechanical spring button in the throttle control assembly that keeps the engine from over revving in neutral...on my 97 Challenger it did this ...run good slow down, put in neutral for a second, put in forward gear ...wouldn't rev over 3500rpms.
Let me know if yours is doing this. I can tell you how to pull the throttle control apart to repair it.
Karl

oh yea, the gas filter is the cup above the gas tank...

 

[Kenner73]

still troubleshooting...

I'm starting to think that my loss of power is coming from the impeller losing traction rather than the engine.

As before, the loss of power happens just before planing. Sometimes it makes it up to plane and then runs fine. RPMs boost to normal on full throttle. Sometimes, it just trudges through the water. But the rpms don't seem to change between 3/4 an full throttle when the boat doesn't plane. It just seems to hold steady.

To remedy, I stop the boat, thrust in reverse, and try again. Sometimes it works, sometimes it doesn't.

I've looked under the boat, and the intake and impeller look visually okay. Is there a good way to check?

 

[kustomkarl]

You need to get a good look at the impeller and the wear ring. If it looks scored up chances are it might need replacing. If you see a large gap around the impeller too will mean it needs replacement.The wear ring wears out so the impeller or impeller jet tunnel won't. To be sure you need to insert a feeler Gage around the impeller to see the tolerance, between the impeller and the ring.

 

[Kenner73]

Wear ring does look worn...

The impeller has a couple nicks in it, and the wear ring does have a few gouges. Does it really affect things?

What would be the average cost to have the wear ring replaced by a pro?

 

[kustomkarl]

The impeller wear ring is like $45.00 for the part, but the labor could run you @ $99.00 an hr. here in Florida, something in the neighborhood 4 hrs.total = $450.00. I'd call around and ask what the shop rate is for the repair. The labor is set at a flat rate in most repair shops. That's why I use the manual on the forum and do my own labor.
Karl

 

[seadoosnipe]

Bearings....

With it being a 95 model there would be a couple things to look for. If your the original owner, then you'd know the answer here. How long has the wearing ring been in the boat? And if you don't know this, then you don't know how long it's been since the pump oil has been changed.
To change the wearing ring, you have to remove the impellor. If you remove the impellor, then you should go ahead and have the bearings and seals replaced too.
If you know how to turn a wrench, you can remove the pump end yourself and take a feeler gage and measure the distance between the pump and the wearing ring. At the center point of the blade to the wearing ring, the distance can be no greater than .040 thousandths of an inch.
You may be able to go through the inlet side and not remove the pump but it's more difficult.

 

[Kenner73]

wear ring

Thanks for the reply.

I just spoke with the previous owner. He replaced the wear ring 2 years ago.

Where could I find a step by step tutorial for replacing the wear ring and the bearings and seals?

thanks

 

[seadoosnipe]

wear ring replacement!

The premium members have access to the manual section which has all the instructions on how to do this task. It really isn't that hard and only one real special tool is needed to do the job. There are a couple more listed in the manual but there are other ways without ordering the expensive stuff. If you get the premium membership and then while rebuilding your pump, get stuck, there are several forum members who have done this with great success that can give you pointers if you get stuck. I just replaced my wearing ring and bearings this past summer.
Here's something to think about. This may not be your problem. You said the previous owner said it was replaced two year ago. It shouldn't be bad this soon. Unless the boat has been constantly run in the shallows along the beach, picking up sand, that ring should be good. You may think about trying to get a feeler gage in from the intake side to check the clearance.