Pontoon Boat & Deck Boat Forum

Last month I had tried (spur of the moment) to take my project out for its maiden voyage and ended up having to tool around for about an hour on my "kicker" motor, because my main motor wouldn't start...I got back to "the yard" and began trying to figure out what went wrong. It took a few hours for me to notice that my automatic choke had somehow gotten out of adjustment....once I readjusted it, it fired right up...after running it from day to day for about a week, I pulled the plugs and they looked fine...
Fast forward to last tuesday, I re-launched.....had a hard time getting it to start, but once it started getting fuel, it would start up with just a "BUMP" of the starter switch...hmmm....after letting go of the launch dock, I backed out, turned around and headed towards open water...
After clearing the "no wake" buoys, I slowly eased the throttle forward and found myself cruising at about 15-17 mph and feeling smooth....I cruised around within about a half mile of the dock for about an hour....going from idle to full throttle and everywhere in between....it ran great for about an hour and a half and then, while at full throttle, it bogged down...I pulled the throttle back to about half and then it smoothed out....pushing the throttle forward again, it would briefly run fine, then bog down again....then surge...then bog...Feeling brave, I turned the key off...just "bumping" the starter, it would fire right up, but idle was rough...I started it back up and headed over to an area of the lake that had a smooth beach area and was protected from the wind....(I had a new set of plugs with me)...I pulled the plugs and the #1 plug was pretty black and pretty wet....#2 wasn't quite as black nor quite as wet. After changing the plugs, it fired right up & I headed back out. As soon as I got in deeper water, I pushed the throttle forward and it bogged down right off the bat...since I had put some sea foam in when I filled the tanks, and seeing how the boat has been sitting for at least 7 years that I know of, I kind of suspected I'd have some issues like this....right now, the plan is to order a service manual, carb and pump rebuild kits...replace all fuel lines, set timing and figure out and adjust the throttle/timing linkage...all in all, I had a pretty good day...I cruised around for about 7 hours, had a good lunch, didn't get stranded and best of all, my pontoons don't seep water....

Just some things to check....

Check to make sure the fuel tank vents are open.

Also, it might be that the fuel pump diaphragm needs replaced, or that the fuel line and/or bulb needs replaced.

Just some stuff to check if you haven't already.

Changing the membrane in the fuel pump is a 5 minute job. Seldom is carb kit needed if you are careful with the gaskets disassembling the carbs. A can of aerosol carb cleaner does the trick. Just screw down any adjustment screws before removing them and more down the "turns".

[quote="Bamaman"]Changing the membrane in the fuel pump is a 5 minute job. Seldom is carb kit needed if you are careful with the gaskets disassembling the carbs. A can of aerosol carb cleaner does the trick. Just screw down any adjustment screws before removing them and more down the "turns".[/quote]

I'm not sure this fuel pump is really rebuildable.... The repair kits I've looked at just have gaskets and filter screen and no diaphragm. https://www.marineengine.com/parts/john ... =Fuel+Pump

Yesterday I took off the fuel supply hose to the upper carb, turned the engine over and fairly strong spurts of fuel came pulsing out...I'm not sure what the pressure should be, but I'm not convinced it's a fuel pump issue because pumping the priming bulb doesn't help....there are a couple other things I'm gonna look at and try, but as much as I hate admitting it, I'll probably have to spend money I don't have on a service manual...timing specs, float specs, etc. etc....

Check to see if your fuel filter/water separator is full of water. That'll starve the engine of fuel at higher RPM's, but it'll run at lower speeds fine.

Most 45 year old motors barely have fuel filters, mich less fuel separators.

I still have my Yamaha 115 no 2/stroke from 1985. It is a 1 hr. Job for me to remove, disassemble, clean, reassemble and adjust the two carbs. And I am not even a mechanic.

The most common problem is needle valves getting gummed up, especially with 90/10 fuels. Thismismwhere the drip, drip, drip you can see Down the endocarditis carb comesmfrom.

And if there is any rubber item in the fuel system, 90/10 will destroy it--like a fuel pump membrane. Fuel pumps are very susceptible to deterioration.

Well, I found a used service manual on line for $24....ordered two carb rebuild kits...and even though I can't really afford it, a fuel pump....I'll do the tune up, rebuild the carbs and take the pump along to change out on the lake in case...it only requires a screw driver and pliers to remove and is readily accessible... hopefully I'll be able to throw it in the tool box to carry as a spare....

Water separator??? Yes...I'd thought of this...I think what I'm gonna do is try and find a small clear one to fit "in-line"...simple, cheap and it's always a good thing to be able to see the fuel in-line...

Well....rebuilding the carbs worked wonders...no more starting fluid for cold startup...Once I pulled the carbs apart, it was pretty obvious that most of my problems were carb related...It's running much smoother and throttle response is what you'd expect from a two stroke...I'm not gonna take it to the lake just yet though...I've got a few minor things I want/need to do first, because if I don't, they most likely will lead to bigger issues...Anything/Everything that the previous could have, should have, may have, or probably or possibly touched, fiddled with, adjusted or even LOOKED AT, is going to be gone over...yes, the carbs were THAT screwed up and I'm really surprised it ran as well as it did for as long as it did...