SXR EME Q8 Sky power/bogging issue.

[JamesG]

I just finished building my eme Q8 and it ran great for the first ride. Stock SXR 800 engine, no mods. I let it sit in the water for 10 minutes, no leaks. I ran it about 20 minutes with no issues and then headed out into some surf. Still ran great, but it had a little water under the hood during the ride. After about 5-10 minutes in the surf, i noticed the ski had very delayed power (bogging i guess?). I immediately road it back to shore. I have been out twice since then, and the problem remains.

Things about the problem I have noticed:
-No low end brap
-delayed power when holding the throttle wide open
-after a few seconds of holding the throttle, it pops out of the water decently
-while riding, if i prime it, the ski has a few seconds of perfect power, but then the power goes away
-it sounds like it is running lean when it's out of the water
-fuel is running through the return line sufficiently

Things I have tried:
-all new fuel lines
-cleaned the fuel tank thoroughly
-replaced the fuel filter
-opened up the carbs, everything looked fine, including the filters
-the pop off was fixed 6 months ago

A buddy of mine thinks there is water ingestion somewhere. A mechanic suggested that I have an air leak. Maybe an exhaust leak?

I'm an amateur, so any help is appreciated. I need this thing running properly before daytona..

Thanks,

James Ross

 

[Cross]

Check the jetting on the carbs. Sounds like its lean.

 

[Str8huckin]

If it ran fine before, it's not jetting. Look for an air leak.

 

[Superjetjim]

If you wind out (richen) you high and low mixture screws 1/4 turn anticlockwise does it improve?

 

[Aircraftsalz]

If you had an exhaust leak you would see smoke after a quick ride when you pop the hood.

Pop off the fuel line from the carb and blow back into the tank, make sure theres no restrictions. I've seen trash get stuck in the tank pickups, which caused this same problem ...

Airleak you can check by spraying some carb cleaner, brake cleaner around the intake, crank seal, etc and see if you get an increase in rpm...

But I think you got a block in a line...

 

[JamesG]

I checked for an air leak with carb cleaner, while running it on the hose, and found nothing.

I blew into the fuel line from the fuel filter and again from where it enters the carbs. I got bubbles in the gas tank both times. So that seems clean.

I have noticed when i first start it up on the hose, it runs decently. Then after a few minutes, if i give it a little throttle, it revs away and I have to kill it. So that sounds like an air leak? Or maybe running too lean?

 

[Aircraftsalz]

If the motor ran fine in your sxr and you just swapped hulls it's not the motor... Unless you removed carbs...

Is the filter full of fuel when the ski is running?

 

[JamesG]

If the motor ran fine in your sxr and you just swapped hulls it's not the motor... Unless you removed carbs...

Is the filter full of fuel when the ski is running?

We only pulled the carbs to install primer. The engine sat for a few months before I rode it, but i fogged it and oiled it during that time.

The fuel filter is at least 75-90% full of fuel when running. I can check it again to be sure if it is completely full.?

 

[Aircraftsalz]

That's about right on the fuel filter.. I have seen the primer suck air around the t fitting .. Try removing the primer fitting from the fuel line... Just cut a new line and bypass the primer... And then retest

 

[McDog]

If it's running away it is an airleak somewhere. Either from the fuel lines or somewhere else. My guess is the fuel lines or primer T somewhere. I agree with Josh for what to do next and I would install all new fuel lines if that doesn't work.

 

[JamesG]

That's about right on the fuel filter.. I have seen the primer suck air around the t fitting .. Try removing the primer fitting from the fuel line... Just cut a new line and bypass the primer... And then retest

I just bypassed the primer T and ran it on the hose. I'm not 100% sure that fixed it, but the ski ran better for sure. I kept giving it throttle and it didn't run away. I guess I will run it in the water tomorrow like that and see if the bypass worked.

Any other suggestions?

 

[LegDragger64]

Crank Seals

 

[powerhouseperformance]

it might also be the vent on the fuel tank is clogged. If you notice with a half tank of fuel in it, it will run good for a few minutes then turns bad its probably the problem. If you have a full tank it will run bad almost immediatly because there is no air space.

 

[JamesG]

it might also be the vent on the fuel tank is clogged. If you notice with a half tank of fuel in it, it will run good for a few minutes then turns bad its probably the problem. If you have a full tank it will run bad almost immediatly because there is no air space.

Aha I was thinking that could be the problem. I will check that too.

 

[Waternut]

Yeah you need to have the engine under load (in the water) to determine if the airleak is completely gone but it definitely sounds like air is getting into the system. Clogged tank vent exhibits different problems so I doubt that's the problem. We discovered with mcdog's ski last year that even fuel lines with tiny cracks at the edge of the fuel line can cause major issues. I would change the fuel lines or at least take 5-10 feet of fuel line with you next time you go out so you can swap out all the lines if something is still screwy.

 

[JamesG]

It wasn't the primer. I'm almost positive that the problem is water ingestion by the way it's acting. I am going to check the head pipe gasket now.

I highly doubt the fuel lines are the problem, they are all brand new, but I will still check them.

 

[McDog]

Water ingestion wouldnt make the motor run away.

 

[JamesG]

Water ingestion wouldnt make the motor run away.

the engine stopped running away. Could have been a combination of a few things. motor sounds decent out of the water now.

 

[D-Roc]

What about head gasket leak?

 

[matth113]

Did you do a Leak down test ?