ox66 engine trouble?

[reefman]

I'm the new owner of a 2002 21sc with an ox66 150 hp with 242 hours on her. Boat was professionally winterized and came wiyh a full tank of fuel. She operated fine on the day I test drove it and on the 11 mile trip across Long island Sound when I took delivery and brought her home. Cruised about 25mph @ 3700RPM. Both of these runs were in flat calm conditions. I'v since notice that when I hit a wake or a small chop the engine really bogs down and seems like it might even stall ( which it never has). The first time it happened my daughter was at the helm and when we hit a wake I thought maybe her elbow hit the throttle, that's how much an affect it has. Next time out on a windy night same thing. Seems whenever the boat lose momemtum the engine fades on me. Couldn't tell you how much the RPM drops off, I'll pay attention next time. She continues to run fine in calm conditions, starts instantly, idles fine and no excessive smoke. Seems like it's starved for fuel when I hit a wave and I'm not talking about 4 footers so something's not right. Maybe fuel maybe prop? If anyone has had this expieriece or has a thought please let me know.

 

[DaleH]

From my direct experience, stalling or RPM loss after hitting a wake is a sure sign of a fuel delivery problem. I'd open up the inspection port above the fuel tank pickup, remove the hose, and using 2 box wrenches 180-degrees apart, remove the square/rectangular boss that the fuel exit barb (most probably an anti-siphon valve barb) screws into.

Clean off the end of the fuel pickup. Also look into the fuel barb and make sure she's clean. There may be a SS ball-bearing and spring in there, as that is what makes it an anti-siphon valve, i.e., fuel can't be spilled from the tank, if/when the fuel line ruptures, but can pulled through it under vacuum by the fuel pump (it pulls open that SS ball).

Re-assemble Permatex 2 gasket compound/sealer.

Some older 2-stroke OBs can also stutter/stall when the carb bowl float gets flukie ...

 

[TomS]

Your VST filter is clogged. Search here for lots of info on how to inspect/clean it.

-- Tom

 

[TimC2520]

Your VST filter is clogged. Search here for lots of info on how to inspect/clean it.

-- Tom

Agreed, very common problem on those motors. If it hasn't been swapped out in the past year or two, it's probably the older design also. You can clean it, but if you want to drop some cash, the new replacement has been redesigned and allows for much more filtering surface and hopefully, less frequent clogging. Even with the new one, they should be checked annually. Good luck with it and let us know how you make out. Many here will help/talk you through it as they did for me when I decided to do my own maintenance.

 

[reefman]

Is that the filter that goes inside the vapor canister? I guess it looks bigger in the picture than actual size because it looks to large to fit in the space I think it is supposed to go. I'm going to change out the filter for the water separator (sierra 10 micron) and change the filter element in the small plastic fuel filter on the engine and see what that does. I fthe problem still exists I'll go after the VST filter, but may defer to a pro as I need to fix this and might be over my head.

 

[TimC2520]

Yup, that's the filter in the vst tank. When I opened the box, I thought "Ugh oh, wrong part, that'll never fit". But it does fit.....I still change it every year. In fact, when I pulled last years out this past March, it had swelled considerably and was stuck in the bottom of the tank. :shock:

 

[reefman]

Didn't get too far with this project. Could only manage to loosen 3 screws so far. Frustration level was building so I stopped before I stripped any. Gave them all a good soaking with liquid wrench and wll try again. Any other tricks to deal with this problem?

 

[TomS]

You did the right thing by not pushing it with the screws. Make sure you are using a #2 screwdriver and it should go much easier.

-- Tom

 

[DaleH]

Could only manage to loosen 3 screws so far ...
Gave them all a good soaking with liquid wrench and wll try again. Any other tricks to deal with this problem?

You can place a well-fitted screwdriver into the head and RAP smartly with a hammer to help loosen the threads. APPLY grease before re-install. use the premium blue-colored waterproof synthetic stuff I LOVE so much ...

 

[reefman]

Thanks for all the advice. Filter changed and problem solved. Very big relief.

 

[Pain Management]

I was bogging down whenever I tried to go over 2000 rpms. When I hit any chop it would go far below 2000 rpms then catch and go back to around 2000 rpms. The problem started suddenly with no advance warning. Friday it ran fine, Monday it was boggig down. I had the vst changed out in March of 08 so I did not think it was the vst. I thought it was one of the lp fuel pumps that went bad but I was wrong. Today I checked the vst filter and there was all kind of gunk on it. I cleaned it with carb cleaner, went for a ride and problem solved, 5300 rpms at 41 mph. Tom is always talking about the vst needing cleaning and is he right. It is going to be the first thing I check if I ever have a power loss issue. Thanks Tom you saved me some money and it was an easy job, about 25 minutes.
George
BTW the right screwdriver is a must. I was at my marina about an hour away from home so I had to go to Home Depot to get the right size.

 

[ppem45]

Reefman, have you ever used PB Blaster instead of Liquid Wrench? I like the PB better. My .02