115 merc loss of power

[brad1975]

I am frustrated, boat seemed to run fine until I changed plugs,replaced bulb and line, used different oil. Will run good for awhile then bogs down to nothing and stalls out, will start back up go for awhile and do same thing. Took family out yesterday after I used different oil (synthetic tc3) and boat did not even want to stay running, same problem but did not even want to start back up, went home and drained all gas out of it. Some of it towards the end looked like sludge. Is it a fuel problem, carbs gummed, HELP!!

 

[ddennis]

Re: 115 merc loss of power

Some tanks have a screen around the pickup,,,,if there was a lot of crud in the tank the pickup screen could be clogged...if no screen check the fuel filter...

 

[skimmer]

Re: 115 merc loss of power

If you've just changed the plugs it's not a bad idea to check the gap 90% of the time they are right but I have had one instance when new plugs didn't fire properly. Having said that it is more likely to be a fuel problem if the fuel filter looks alright, clean your fuel tank thouroghly and I'd start by giving your carbie a good clean and pay particular attention to your jets!

 

[AMD Rules]

Re: 115 merc loss of power

Start with the fuel tank and work your way up to the carbs. Sounds like the entire fuel system needs a good cleaning.

I've seen it quite often where a small piece of deteriorated fuel line makes its way up to the main jet and clogs it. The fact that you had been installing new lines suggests you may have something blocking the carbs intermittently.

Double check compression and spark on all six, just to rule out electrical issues.

Take your time, and you'll find the problem.

 

[Laddies]

Re: 115 merc loss of power

Sounds like a heat problem, either lean (fuel system) or cooling. In as much as it started with the maint. then it's probably fuel or lack of it, You said that you went to synthetic oil (why?) it still needs 50 to 1 mix and a lot of older engines relie on the regular oil as a sealant for rings. Which ever end you start on tank or carbs don't let the engine continue to seize or you won't have to worry about it as it will trash it's self out. Fix it quick

 

[Chris1956]

Re: 115 merc loss of power

Brad, Don't forget the fuel filter screen on fuel pump. If you have the backdrag carbs there is a screen under the brass fittings that fit into the carb bowl covers. If conventional carbs, there is a banjo fuel fitting under the carb bowl covers.