92 SP boggs at WOT

[nb141fd]

Recently I had a problem with warm starting. After much help from this board I found out it was a battery problem. It took me 3 batteries until I found one (Odyssey) that was good.

I now have another problem that I hope someone can help me with, my SP boggs (I think that is the correct term) at wide open throttle. It accelerates through the range fine and will run at WOT for five or six minutes then act as if I throttled down to 1/2 throttle. If I then release the throttle to about 50% I can increase rpms slowly to WOT again. It will do this continually every five or six minutes. It has not died once while doing this.

Here are some of the fixes I've tried:
New fuel lines and fuel filter
Cut back the plug wires by a 1/4"
New fuel selector valve
SBN44 (after market) carb completely rebuilt including new N&S valve
Carb pressure tested as well as Pop-Off (20psi)

The ski has a K&N FA and Coffman pipe and runs 117.5 and 150 jets with the low speed adjuster set to 1 1/4 turns and the high speed at 1 turn out. These settings were on board when I bought the ski used. It also had NGK BR8ES plugs which I changed to BR7ES. The plug change wouldn't have anything to do with a bog would it? Any ideas on where to begin looking for a solution would be appreciated. Thanks

[1fastski.com]

Re: 92 SP boggs at WOT

make sure the hood is not on the fuel tank breather when shut

[surveyguy]

Re: 92 SP boggs at WOT

what is your compression? I wonder if the reason you did all this work was because the engine has been through trauma already. If all is good, may I suggest a block compression test.

[Bill O'Neal2]

Re: 92 SP boggs at WOT

When it bogs down, what do the sparkplugs look like?

Are they wet and fouled?

The fuel tank breather hole covered by the rubber piece where the hood meets the hull by the steering can get blocked. When this happens, the fuel lines vapor lock. Make sure it is not blocked. This is what Chris was reffering to.

[nb141fd]

Re: 92 SP boggs at WOT

Bill, thanks for the reply. Unfortunately I didn't pull the plugs when it bogged and I coasted into the dock area when I was done. The plugs currently are slightly moist and have carbon deposits on them. I know this doesn't help because you need to see the plugs at WOT. I pulled the carb again and checked the filter and it was spotless. I also checked the fuel tank breather lines that are located in the front of the SD and they are both clear and working. In addition, the front fuel filter is clear and the "square" O-ring is present.

Surveyguy, I checked my compression and got 140 on the mag cyl and 145 on the pto.

[surveyguy]

Re: 92 SP boggs at WOT

were the diaghragms good, especially the pump side, (outside, atomosphere side)? Those are supposed to be flexible. Sounds like you're just not getting fuel at WOT, so I'd guess fuel pump or carbs.

[Bill O'Neal2]

Re: 92 SP boggs at WOT

Another possibility is an exhaust leak inside the hull.

When we said check the fuel vent lines, we meant does the hood block off the vent line hole when you shut the hood cover ? Very common problem on your model, and the symptom is shutting down after running breifly for lack of fuel.

[nb141fd]

Re: 92 SP boggs at WOT

Bill, the vent line grommet had apparantly been lost and the hose was secured to the left wall by a zip tie, clear and away from the hood cover. Am I correct that both this vent line and the one connected to the front vent baffle allow air into the fuel tank (when I blow into the hose) but prevent air from escaping (due to check valves) from the tank? Thanks for the heads-up on the exhaust leak, I'll double check all pipe and exhaust connections. By the way, is there any test for this other than checking the clamps and connections?

Surveyguy, when I checked the Pop-off (20psi) I also did the fuel diaphragm leak test as outlined in the manual and everything check out.

[Bill O'Neal2]

Re: 92 SP boggs at WOT

Air vent sounds good.

Start the motor and look for smoke in the hull around the pipe, muffler and hoses.

[nb141fd]

Re: 92 SP boggs at WOT

Bill, I was checking the exhaust system, clamps and connections and hit upon something. The connection between the Coffman Pipe and the Exhaust Cone was slightly loose. I've attached a picture which shows some slight exhaust stains (you have to look closely they are behind the left clamp stem and nut) on the Coffman pipe. Would something like this cause my WOT bogging problem? In addition, I pulled the fuel tank and drained it. I checked some of the fuel that came out and it looked pretty clean. I shook up the fuel container and put some in a clear bottle and could not see any water droplets in the bottom after letting it sit for some time.

[frankey01]

Re: 92 SP boggs at WOT

Yes

[nb141fd]

Re: 92 SP boggs at WOT

Bump

[frankey01]

Re: 92 SP boggs at WOT

Did you fix the clamp and did it solve the bog since you had the leak you may need to go in and retune your carbs to the changes made by fixing the leak

[surveyguy]

Re: 92 SP boggs at WOT

gotcha nb, hope that thing's screamin' again !

[nb141fd]

Re: 92 SP boggs at WOT

Frankey and Surveyguy, I won't have a chance to get into the water until next week. I was able to fix the clamp and get a good bite on the connections. I'll post next week and let you know if the problem is solved. Wish me luck.