94 15m Mariner

[MHFD112]

I posted a week or so ago about my motor. Wouldn't idle real good and after 5 gallons or so of fuel through it would be hard to start. Plugs looked to be new but fuel fouled. I just bought the motor not long ago so I took it back to the dealer. I called today and they checked compression and timing. Said both were good and reset the carb. Do you think my troubles are over?<br /><br />Going to pick it up tomorrow and see how it does. As long as the plugs are fresh it starts easy and runs good. I also noticed it would idle smoother and faster with the cover off.

 

[MHFD112]

Re: 94 15m Mariner

Picked up the motor this morning. Compression is 120 in both cylinders. How does this compare to a new motor?<br /><br />They said the reset the float. Hope this fixes the problem.

 

[drothman]

Re: 94 15m Mariner

MHFD12:<br /><br />My '97 Mariner 15 and my buddy's '96 15 behave much the same. Advice he got included de-carboning the engine regularly and always using either Mercury or OMC Ficht oil (for the anti-deposit additives). Apparently, these motors have a reputations for loading up with carbon deposits. Also, service folks recommended going light on oil (70:1) if just using the motor for trolling. I had the carb on mine rebuilt by a pro, but that didn't solve the problem. Both our motors act like they run too rich- but both have been serviced by factory approved dealers. Hope you have better luck with yours.<br /><br />Wish my Mariner ran as well as my Evinrudes...

 

[MHFD112]

Re: 94 15m Mariner

What is decarboning? <br /><br />I'm sure everyone has either thought of or tried these ideas. What about synthetic oil and higher octain fuel? What about running all the fuel out of it when done? I don't do much trolling so I had better stick with 50:1.<br /><br />If I have to I can clean the plugs up before I go out. Not very convenient, but it is better than getting it flooded out on the water.

 

[drothman]

Re: 94 15m Mariner

De-carboning involves warming up the engine, then spraying an engine deposit remover (OMC calls it "engine tuner", Mercury makes a similar product) down the carburetor until the engine stalls. Let the engine sit for a while (follow the directions on the can), then start up and run the engine. This removes deposits from the cylinder and exhaust, usually lots of carbon.<br /><br />Running all the fuel out of the engine at end-of-day isn't the answer- I always do that and still have problems with my Mariner. I don't expect different fuel or oil to help- it's the engine design that's at fault. Small Mercury outboards just seem to need lots more attention than OMC's.

 

[Hooty]

Re: 94 15m Mariner

If the plugs are just wet and not carboned up (black and nasty), adjusting the float may solve your problem. Usually if the engine is carboned up, the compression will be low (rings).<br /><br />c/6<br /><br />Hooty

 

[MHFD112]

Re: 94 15m Mariner

These were just wet. Not much carbon. I hope to use it some tomorrow or the next day. <br /><br />Will post results.

 

[MHFD112]

Re: 94 15m Mariner

Went out today for the second time since the dealer looked at the motor. All was well. Ran synthetic oil and 93 octane. Ran the same, but started really easy. Ceramic part of the plug and electroade tip were dry and tan.