Hard starting 3hp Johnson

[dogdaysllc]

Mid 90’s Johnson 2-stroke 3hp. Model J3REOD.

Motor is nearly impossible to start. However with just the tiniest squirt of starting fluid into the airbox it fires right up and runs great. I read that starting fluid on 2 strokes is bad so I’ve been spraying some gas/oil mix instead. It’s not nearly as effective as the starting fluid but I can eventually get it running. I’ve replaced the plugs, fuel lines and cleaned the carb (which is spotless). I’ve adjusted the air/fuel mixture screw to where it seems to like (about 1.5 turns out). It would seem like it’s not getting adequate fuel when cold since it fires right up with the starting fluid. Any suggestions?

 

[Crosbyman]

did you clean out all passages. including the orifices and drip chamber on top of the carb

choke plate closes ok ??

move throttle up a bit to start

 

[racerone]

Verify operation of the choke linkages and choke flapper.----Plastic bits on there that may have broken.

 

[oldboat1]

Idles smooth at your air/fuel mix?

 

[dogdaysllc]

Thanks for the quick replies. The choke flapper works perfectly and it seems to idle/accelerate/handle load fine once its running. When cleaning the carb I did make sure all the passages and jets were spotless. I’m not sure what the drip chamber is though. Can you elaborate?

 

[Maj92az]

I had a lawnmower that would do that. EVENTUALLY it would run ok... But it ended up being a vacuum leak between the engine and carb. The power or lack of while starting (pull starting) was not enough to create a venturi.. But once and if engine ran it could pull some fuel... I wonder if there could be a leak..maybe somewhere with reeds..

 

[dogdaysllc]

Thanks for the reed valve suggestion. I’ll look into that.

 

[oldboat1]

Think I would revisit the carb cleaning even though it seems clean. Need to take off the domed fitting on top (See Crosby's post, #2) There are two or three holes up there, and the orifice for the needle could be partially blocked. The vertical nozzle up through the middle of the carb needs to be squeaky clean -- think there is a jet at the bottom as well. I disassemble the carbs and soak tops and bottoms in lacquer thinner, then run soft wire in every opening and follow with carb spray.

 

[Crosbyman]

see diagram page 107 this is an older carb but same principle there are 3 very small holes under the dime size plug ​

just above the speed control plate

see procedure at 5:08 on this video for a 9.5 ​

https://www.youtube.com/watch?v=r-VTkOuSg00

procedure involves drilling a hole in the plug using a 1/8 drill bit just puncture the plug no more !! pull it out with a pick or nail ... clean the 3 holes reinstall a dome plug and crimp it down with a flat head punch (just enough to push it down then seal the rim with clear fingernail polish (that is what I use) ​

http://boatinfo.no/lib/johnson/manuals/1922-1964johnson.html#/112​

 

[dogdaysllc]

Thanks guys. I just pulled the carb and tested the reed valves by taping a little piece of paper in front of the chamber. Lots of suction when I pull the starter cord which indicates the reed valves are working properly. I’ll dive deeper into your carb suggestions and report back

 

[Crosbyman]

suction does not mean the reeds are working… they are likely ok anyway suction only tells you that they are not stuck shut and will allow fuel fumes into the crankcase.

the main job of reeds is to CLOSE on the down stroke so the fumes sucked inside the crankcase from the carb have nowhere to go but inside the cylinder IN ports on the up stroke.

if you have good 5/16 sparks and decent compression I would as you indicated…. focus on the carb for now..