Seadoo GTS needs help. The rear cylinder is flooding out with fuel.

[dporscheguy]

I have a 1999 Seadoo GTS 717 with a single carb. The rear cylinder seems to be flooding out with fuel.

I've had to turn fuel to the off position to get it to start or it will get flooded easy. When I do get it running is sounds bogged down and seems to sound better with a few revs. When I shut it off, I pull the plugs out and the rear cylinder is always soaked with fuel and the front one is dry. I took it to lake and it had no power and barely ran, but occasionally the power would come on and it hauled butt. When I pulled it in the last time it sounded different and stalled out just before I got to shore. When I tryed to start it it acted like it had a dead battery. I then tought it might be hydro-locked. I pulled the plugs and gave it a spin and sure enough water shot 5 feet in the air out of BOTH cylinders. I cleared out the water and was able to get it started and its still got the same rear flooded rear cylinder issue.

Below is what I have done to ski since I first received it not running:

Checked Compression is about 140 per cylinder
Rebuilt Carb - it didn't look that dirty. I was told by boat mechanic to only replace soft parts.

I originally turned low screw out 1.75 turns, but i couldn't keep it running at idle. I found another web site that said the original factory setting was 1 turn out. When i did this I could get it to idle.

Replaced all fuel lines.
Completely cleaned fuel tank, filter, fuel sending unit, and fuel petcock.
Installed new battery.
Checked all fuses.
Checked all electrical connections.
Cut spark plug wires back.
Switched out coil and wires from my other running ski - no change and I put bad ski's coil and wires on my running ski and it ran perfect.

I had a guy suggest to me that the diaphram in the carb may have a leak and the fuel could be running back down the pressure pump hose.

I am pretty good with mechanical problems, but this thing has kicked me in the balls.

Please Help,
Doug

 

[LouDoo]

Hi, and welcome to the SeaDoo forum.

The thing that bothers me is water in the PTO cylinder, sounds like it might be a bad "O" ring, part no. 5. However I would think if the "O" ring was bad it would effect the compression. The first thing we need to find out is how water is getting in the rear cylinder, or you could ruin you motor. I would go ahead and pull the head, it's really no big deal, and see what's going on. Here's a parts diagram.

http://partsfinder.onlinemicrofiche..._oem/Seadoo_PWC.asp?Type=18&A=65&B=5&Action=T

Since you have a single carb. I'm suspecting the rotary valve is the problem with gas flooding the rear cylinder, are you sure it's gas and not water?

Lou

 

[dporscheguy]

Thanks for the reply. I edited my post to clear something up. When the water came out, it came out of both cylinders. What are the chances of both cylinder orings going bad? Is it possible to look at the head without replacing gaskets or orings?

Doug

 

[LouDoo]

Probably not too likely, however, I think I would still pull the head, if there's water in the cylinders you need to get it out. At the very least spray some fogging oil down the spark plug holes and turn the engine over a few times. I'm assuming you live in Sebring, FL. If not and you live in the north is there a chance this ski was not winterized last year?

Try PM'ing Dr Honda, I think he's on line, see what he thinks.

Lou

 

[dporscheguy]

I justed re-checked the compression and got 130 in rear and about 138 in the front cylinder. When I checked before they were closer together and i thought they were in the 140-150 range. I pulled the head of to look at o-ring number 5 and they look ok by visual inspection.

If the back cylinder wasn't firing could this lack of pressure enable water to enter the cylinder through the exhaust.

You mentioned rotary valve could be the rear flooding culpret.

How do I check the rotary valve?
What needs to be replaced?
How difficult is this to do?

Thanks,
Doug

 

[Dr Honda]

Hi Guys,

Ummmmmmmmm.......


Some random thoughts first....

1) with a single carb, you can't be fuel fouling one jug, and not the other. It's impossible since it's feeding both.

2) If the engine will start at all... then the Rotary valve is spinning. Even if it was out of time, it would cause the same prob in both jugs.

3) some water getting in the jug... mixed with fuel/oil will smell like wet fuel.

4) now that your are saying that the rear jug is down at 130 psi... I'm going to say it may even be lower than that... and wet rings are keeping it artificially high.


I'm going to go re-read everything... and post again shortly.

 

[Dr Honda]

OK... now that I red over all of it... you may have a few issues.

1) you may have a weak spark. If you don't fire the jug... the plug will get wet, and foul. (but I don't think this is the real problem)

2) you have a serious water leak in the engine. If the engine was running (good or bad) the air going though it will push the water out. Since you said that it stalled, and both jugs were full of water... that is the real problem.

No... I don't think both #5's went bad... but you are getting water in from somewhere... and if it was enough to stall the engine... that's not good. (that could have been enough water to bend a rod)

3) at 130 psi... a Seadoo engine isn't going to run very well. So... regardless of what you find wrong... that engine is in need of a rebuild. (compression spec is 150 psi)




With that said... I would remove the jugs (cyl's) and check the crank for rust. Also... the base gasket could be leaking water into the engine. So... that will also be a good time to check the case, jugs, and head for straightness. If the pistons, and cyl walls are OK... you can install new rings, and re assemble the engine. Hopefully, you will seal up any leaks that were there.

 

[dporscheguy]

Wow. Now I'm really depressed. Thanks for the reply. I really didn't think it was water in the cylinder, cause Ive cleaned or swaped the plugs and blown out the cylinders, started it for a couple of seconds with no water and shut if off. I pull the plugs and the same rear wet plug condition exists.

When I ran it on the hose, I didn't have a complete filling of the cylinders, but the lake is where this problem became obvious.

I don't know If I want to do the rebuild. Maybe I should cut my losses and just sell it as a project for someone else at this point.

Doug

 

[dporscheguy]

I'm glad I haven't decided to pull engine apart just yet.

I decided to try to see if fuel was in fact going back down the pump hose coming from the crank case. I pulled the hose and put a long clear hose in its place. Low and behold the hose completely filled with fuel. I emptied the hose, turned the engine over with fuel off and plugs disconnected and made sure there wasn't any extra fuel coming out of the crank case. I put the clear hose back on, turned on the fuel and reattached the plugs. After running for a couple of seconds fuel started heading down the hose from the carb into crank case.

What could be causing this?

Everything looked OK when I opened up the carb, but I thought maybe I would try replacing the check valves, but I haven't received them yet.

Doug

 

[lucky99]

Let us know what you find, I have a 98 GTS doing the same thing.

 

[dporscheguy]

It's alive!!! 99 GTS is fixed and runs perfect!!!

When I got this seadoo the carb was out and partially taken apart. I was given a rebuild kit with it that had instructions. The kit worked for the BN 44 and the BN 38. My carb is the BN 38. The instructions were a little misleading to someone like me who knows nothing of how the pulse portion of these carbs work. When I put the carb together I didn't install the clear diaphram in-between the check valves plate and the top cover. They showed this on the picture of the BN 44, but not on the BN 38. After talking to a seadoo mechanic, I realized that I left out this crucial part. I installed this part and the gasket on top of it and wammo.... it fired up and ran perfect.

I took it to lake yesterday and It ran Perfect!!! No hydrolock, No flooding, No problems at all.

I made a bonehead mistake, but I'm sure glad I didn't just give up when i was told it needed a rebuild.

If you are having this problem, try using the clear hose trick. Got mine from Advanced Auto in the lawnmower section for about 3 bucks. I hope this helps others.

Doug

 

[Bills86e]

Wow. Now I'm really depressed. Thanks for the reply. I really didn't think it was water in the cylinder, cause Ive cleaned or swaped the plugs and blown out the cylinders, started it for a couple of seconds with no water and shut if off. I pull the plugs and the same rear wet plug condition exists.

When I ran it on the hose, I didn't have a complete filling of the cylinders, but the lake is where this problem became obvious.

I don't know If I want to do the rebuild. Maybe I should cut my losses and just sell it as a project for someone else at this point.


Doug

Check the fuel line routeing, you might have a fuel line hooked up to the pulse nipple on the engine case.

 

[bigJake]

When I got this seadoo the carb was out and partially taken apart. I was given a rebuild kit with it that had instructions. The kit worked for the BN 44 and the BN 38. My carb is the BN 38. The instructions were a little misleading to someone like me who knows nothing of how the pulse portion of these carbs work. When I put the carb together I didn't install the clear diaphram in-between the check valves plate and the top cover. They showed this on the picture of the BN 44, but not on the BN 38. After talking to a seadoo mechanic, I realized that I left out this crucial part. I installed this part and the gasket on top of it and wammo.... it fired up and ran perfect.

I took it to lake yesterday and It ran Perfect!!! No hydrolock, No flooding, No problems at all.

I made a bonehead mistake, but I'm sure glad I didn't just give up when i was told it needed a rebuild.

If you are having this problem, try using the clear hose trick. Got mine from Advanced Auto in the lawnmower section for about 3 bucks. I hope this helps others.

Doug

ummm, you do realize that replacing the carb diaphram may have got the ski running but has absolutely nothing to do with why your engine is filling with water. unless you left out some details , like you towed it in when it stalled or you ran in on the hose without the engine running, it sounds like you still have a serious problem to resolve.