Gutless 115 tower of power

[Throbbin Rods]

Merc 115 HP inline 6 - Gutless<br />Well, I spent a lot of time working on this last year and finally gave up the ghost and ran it slow for fishing and skipped the skiing/tubing/boarding deal. Got it out this week and as I suspected, nothing has improved. I can only get about 4300 RPM at WOT. Takes forever and a minute to get on plane weith me and my 7- lb daughter. Once on plane runs fair. Motor is a 1988 25 " shaft on a Starcraft Islander 191V. Tank has been flushed and cleaned. Carbs have been rebuilt. Stator has been tested and is OK per Marine Mechanic. Anti Siphon valve is OK. Throttle valves are opening all the way. I am presently saving up my pennies for a Johnson or Evnirude 150HP, which is what the boat is rated for. Course thjat will take ten years. I have only owned two Mercuries and both of them cost me money and gave me trouble. Is it my aftershave?

 

[ZmOz]

Re: Gutless 115 tower of power

Sounds like you're overpropped. Don't blame the motor if it is setup wrong.

 

[DJ]

Re: Gutless 115 tower of power

Agree with ZmOz.

 

[LubeDude]

Re: Gutless 115 tower of power

Has the boat always ran like that while you have had it? If so, then it is probably the prop like mentioned.

 

[Chris1956]

Re: Gutless 115 tower of power

T-R I would check to make sure you are running on all cylinders. My IL 6 runs pretty smooth on five cylinders. Check spark plugs for fouling and while you are at it, check the compression.

 

[CaptainPuget]

Re: Gutless 115 tower of power

I used to own an 18' Chieftain which is almost the same as your boat. "Gutless" is subjective but mine did OK with 70hp and was somewhat scary with 110hp. But if I remember right it took a 20" shaft engine. Maybe your motor is too deep in water, maybe you're over propped, maybe both. A 17" pitch should be about right, 19" probably too much, 15" will move everything that isn't tied down to the back of the boat.

 

[Throbbin Rods]

Re: Gutless 115 tower of power

Thanks all for the feedback. I base my Gutless comment on comparison with an identical boat I owned some years back with a 90HP Johnson. That would have kicked this 115's butt. I have checked compression, all around 105, all within 6 % of each other. I have considered the prop and am looking to remedy that, but to one respondents point it ran better when I first bought it. It would plane off in 5 seconds or less and top out around 40-42MPH. I would be ecstatic if it would run that way again. It has been frustrating. Any and all comments are welcome - maybe between all of us we can figure it out.<br />thanks to all<br />bill

 

[ZmOz]

Re: Gutless 115 tower of power

Have you decarbed lately? Maybe you should try rebuilding the fuel pump, it's just a $4 kit.

 

[PACERll]

Re: Gutless 115 tower of power

It sounds like you have possibly to different problems. First I would decarbon the motor for sure . Then with the boat on the trailer check to see where you propshaft is in relation to the very center of the running pad. To start with you should be 1 to 1 and half inches below the center of the pad with the motor trimmed under. If not you have a setup issue that can be remedied by moving the motor up on the mounting bolts till it hits the above mentioned specs. After this is done you should be able to spin anywhere from a 19pitch to as much as a 23 pitch wheel depending on the load it is pushing. You will know your close when at around 5000 rpms the motor rpms come up but no increase in speed. Hope this helps you.

 

[jimmbo]

Re: Gutless 115 tower of power

To me it sounds like it is getting spark on only 5 cylinders, or one or more of the carbs has a sticking float. RPM range for this engine is 5000-5500. Are you sure it ia an 88? I thought the 88s were the 4 cylinder models.