Mercury 175 Sport Jet bogs down under load!

[Matt Seedorf]

New guy here, I just purchase a 2004 Sugar Sand Mirage. It's a cool boat but won't even make 10mph on the water. This is one of those deals I should have probably walked away from. The boat runs fine on the trailer but in the water it can't get out of it's on way! Has anyone else had a issue similar to mine? Any response is appreciated. Thanks!

 

[tdonoughue]

Howdy and welcome!

Disclaimer: I don't have a Sugar Sand (never have), but do know jets a bit.

Usually the problem like you describe is cavitation. If the engine sounds like it is going just fine and all, but you can't get any speed or pickup, frequently there is something on the intake path or at the impeller that is causing turbulence, which then causes the impeller to cavitate. That can be gaps in the intake path (like where caulk fell out), bolts or screw heads exposed right before the intake, or a chopped up impeller (from sucking up rocks, etc.).

Not sure how easy it is on your model, but you may want to see if you can pull the pump to examine the impeller and the intake path. Send us some pics of those and let's see what they look like.

 

[Weeb]

Carbs gummed up?

 

[anmut]

Those Sugar Sands are sweeeeeeeet little boats!

Start with the basics: Clean carb, replace plugs. Check your jet tunnel for obstructions, check your impeller and wear ring for damage. Is your bucket moving correctly? If engine has proper power and RPM, then check driveline / pump issues.

 

[Matt Seedorf]

Hi guys, looks like a swing and a miss on the impeller problem. I measured a total clearance of wear ring to impeller of .042” . The spec says.038 - .058 so it is actually in really good shape. I have attached some pictures hopefully you agree it looks fine. The cavitation holes aren’t that bad I guess.

I am still wondering now that I may have an ignition problem. I pulled a few spark plugs out after the last time I ran it, they were still wet with gas/ un burnt fuel. It was really hard to get the boat started at the dock to load it on the trailer too, acting like it was flooding it self out. Although it ran pretty good on the trailer a few days later. I have replaced the stator and rectifier because of a it wasn’t charging the battery, so the stator shouldn’t be an issue.Do you have any other ideas? Thanks for your help, I am in NW Ohio and I can’t find anyone that will even look at this thing to help get it running!

 

[Ronnie]

I had a euroline cyclone with a 175 hp Mercury sport jet. It started becoming hard to start and eventually wouldn’t start at all in the water. I replaced the funny spark plugs (no protruding electrode) but that didn’t help. I ended up having all three carbs rebuilt which resolved the problem. The certified mercury tech told and showed me that the needles in each carb were delaminating, first time he had ever seen that and he ended up sending the needles to mercury. If I could do it over I may rebuild the carbs myself if i could get comfortable re setting the pop off pressure of each carb.

Good luck in identifying and fixing your problem.

 

[tdonoughue]

Yes, that impeller looks pretty good. Leading edge is completely clean. You do have some cavitation holes there (so something is causing some cavitation, but not enough to make this issue).

So then I guess we are at the carbs...