Carb> question

[swordfish25]

Working on a 1984 mariner 115 inline. The top 2 cyl ran lean and started to burn the piston. The 1/8 in. hose that goes from the venturi to the top of the float bowl was split.Will this cause a lean condition or is it an overflow?I It runs good on the mufs, but at higher speed it leaned out.(top carb only)You guys are a great help. THANKS

 

[Chris1956]

Re: Carb> question

That little hose is for the backdrag effect. The hose will introduce some vacuum into the float bowl, slightly leaning the mixture at high speed.

Your problem is likely dirty carbs. Clean them up well.

 

[swordfish25]

Re: Carb> question

The carb is as clean as a new one. No fuel restrictons. I ran it fairly hard towing a small alumn. boat slow,for three miles, ane maybe it was running on the lowspeed jets at the time. I will replace the pitted piston, but don`t want it to happen again. I was told to up the jet size and back the timming 2 degrees. I hope this will do the trick. Any other sugestions?

 

[starcraft1982]

Re: Carb> question

JMO,you need to replace the pistons,and anything else to make it right.Then you need to go through motor,cleaning,testing and checking everything.Lastly you need to set everything TO SPEC. acccording to your service manual.Outboards dont like to be "altered".Fix,clean,and adjust to spec.Simple,really. Also,would be a great time for ALL new gas lines,hoses,bulb,etc.

 

[swordfish25]

Re: Carb> question

Because of this junk fuel, I thought it would better to oversize the jets, and back off the timming 2*.I am sure they were not set up for this crap. Am I wrong about the changes.

 

[starcraft1982]

Re: Carb> question

pIm sure others may have different opinions.Mine is that these engines will handle todays fuels fine PROVIDING you keep good,fresh gas in it and run frequently.If you dont go through a full tank in a couple weeks you need to treat it AND install a fuel/water separator.Separator is good regardless of how frequently you run.The big "E"can and will mess w/lines,bulb,and some of the rubber in your carbs,in time.So best to nip it in the bud now,while youre down anyway.Theres some on heree that seem to blame EVERY issue related to fuel on todays gas.While some may very well be,you CAN take precautions,relatively inexpensively.Best of luck in your "rebuild".Done right,it will purr again AND last.

 

[swordfish25]

Re: Carb> question

Thanks, I do have a water seperator on now. I cut it open, and it too was totaly clean. Like I say it has been running fine until I towed a small boat back from the island about 3 miles, and it was running on the idle jets about 1800 rpms. I think this started the pistons pitting, and when I ran it harder the next day it made it worse. If the alumn. haden`t shorted that cyl. out I think is would have done more damage. It runs fine on the mufs right now. That cyl. still has 120 lbs comp.,the rest 135. I think I can save it. The fuel lines are the gray ones. I thought those were neaoprine.