Motor issue mercury 175 hp sportjet on Sugar Sand Mirage

[schnur07]

I have a Sugar Sand Mirage with the 175hp sportjet. When cold it would run ok for 5-10 minutes then suddenly it felt like it lost about half its power still ran smooth but sluggish. I took it to a mercury mechanic and he replaced the stator. I put it in the water and it ran at about half power still. I took it back to him and he replaced one of the CDI units - he showed me the old one and it was cracked. He said he tested it in the shop and all six cylinders were firing. I launched it today and seemed to be idling well and then a sudden change in idle. I went to take off and same issue - very sluggish taking off with top speed at 30 mph instead of 50mph. Could it just be the other CDI went bad or is there something else the mechanic could be overlooking? I'm already into this about $900 on a boat that's barely worth that much.

 

[Chuck Buck]

The clue provided about running OK cold makes me think an electrical component is heating up and failing. Mercury says the switchboxes (CDI unit?) should be replaced in pairs. Since one was “cracked” I have to think the other is toast unless recently replaced. Is there a date code on it?

 

[schnur07]

Thanks for the reply Chuck. Not sure how to find a date code, but the boat mechanic said the stator he replaced was the original so wouldn't be surprised if the switch box was original. He's thinking he needs to replace the other switch box (he referred to them as a CDI) but I just wanted to make sure it couldn't be something simple he's overlooking. Another switch box is going to be another $450!

 

[Chuck Buck]

I’m confused. According to NADA, in 1996 Sugar Sand exclusively used 120 HP SportJets (see screenshot below).



This would mean it’s a 4 cylinder and requires only one switchbox (CDI # 114-6866). Yet you say it’s a 175 HP, which implies six cylinders. What gives?

 

[schnur07]

I might not have the date correct but it is definitely a 175. I would have to look at the title for the date.

 

[Chuck Buck]

Exact year isn’t important so long as it’s a 175 (97-05). Fleabay has new CDI Switchboxes for around 250 clams (114-4953-32). Personally, I’d replace it myself rather than pay that person YET ANOTHER $200 labor. For someone with even basic mechanical skills, it ain’t that hard.

 

[WILL IHNE]

This could also be the carburetors are in need of some cleaning.
Some questions are how does it run on the hose?
What is the idle on the hose? Should be about 1800rpm on the hose and 1200rpm in the water if my memory is correct.

 

[Diplomasta]

Don't ever go back to that mechanic. That is NOT acceptable troubleshooting. All inputs to switchbox can be tested. All outputs can be tested. There is no excuse for guessing at a switchbox. A real boat mechanic must be certified! Would you go to an uncertified doctor?! You need someone to actually troubleshoot this. There is not enough information here for me to help you. (Certified marine tech since 2001).

 

[Chuck Buck]

(Certified marine tech since 2001).

Awesome! We can use all the help we can get with this powertrain!