Merc 115-poor hole shot

[Cobra16]

Hi folks<br /><br />I have a 1980 Merc 115, it's an inline 6. It has developed a lack of power when pulling up a skier- it used to snap them up.<br /><br />I replaced the black box and distributor a few years back. The compression ranges from 130-145 across all cylinders.<br /><br />The only other symptom is that when I first took it out this year (and last), at about half throttle on up, it seemed to lose power them regain it as if someone was flipping a switch. Hard to describe but it was as if the fuel supply was lacking for a second or two. This process would repeat off and on for the first few hours, then it smoothed out and ran fine-except for the lack of low end power.<br /><br />Fuel is fresh.<br /><br />Any ideas?

 

[kevlar3000]

Re: Merc 115-poor hole shot

I had the same prob with a 77 Merc 1150. It was set too lean, so I opened the Carb adjustment screws 1/4th turn and it did the trick, never a problem again, til it blew up. lol<br />Is it propped right? Is it running at normal rpm range on the top end? Does your primer bulb stay hard? Air leaks in your fuel line can be a trigger. Perhaps a bad fuel pump diaphram.

 

[Cobra16]

Re: Merc 115-poor hole shot

I have 15,17 and 19 pitch props, all exhibit the problems. The RPM range is the same as before I experienced these problems. Old ball used to deflate so I replaced it(it was old and worn).<br />Haven't checked for air leaks but will do. <br />Would rebuilding the 3 carbs help?<br /><br />Are you serious about the mixtures?<br /><br />Thanks

 

[corm]

Re: Merc 115-poor hole shot

I would put new needle & seats, and floats in it.<br /><br />corm

 

[Bruno]

Re: Merc 115-poor hole shot

my mariner 115 used to fall on its face about 1200 rpm.Took it to a really good tuner,he changed the mixture on the low speed jet and the thing still works like a bear.

 

[hunt-fish.com]

Re: Merc 115-poor hole shot

Check every hose clamp on the fuel lines first. I've had several problems with the black plastic ones specifically. They dry out and crack open. After that try running Marvel Mystery oil mixed in gas through the system, read the directions on bottle. If the accelerator pump on the carb is gummed up it will cause this problem. If it's sucking air it will cause it also or if there is a fuel blockage.<br /><br />Good Luck,<br />John<br /> http://www.hunt-fish.com

 

[kevlar3000]

Re: Merc 115-poor hole shot

My Merc 1150 would kill when I punched the throttle. With or without a skier. The opening of the jet screws 1/4th a turn on each carb fixed it for me. Instead of the normal 1- 1/2 turns from being lightly seated<br />they were 1-3/4th open.

 

[Cobra16]

Re: Merc 115-poor hole shot

Thanks for all the info, is it difficult to rebuild the carbs? I've done automotive carbs but not these. <br /><br />Thanks again <br />BR