1977 115 Hp Johnson that sneezes/spits

[saltwaterbluefish]

1977 115hp Johnson

After fixing a water pump issue on this motor, I finally got her started, however, after about 5 minutes you here sneeze or spit back for a second and then return to normal. I went through and cleaned the carbs, but still no luck fixing the sneeze/spit. I did a search and someone who had a similar issue said it could be the reed valves need cleaning. If it is the reed valves how do you get to them?

 

[rockyrude]

Re: 1977 115 Hp Johnson that sneezes/spits

What you describe sounds like what is commonly called "lean sneeze". If you set the carbs up on the muffs, you need to get the motor in the water to do the adjustments correctly. The muffs don't create the back pressure that the motor sees in the water, changing the carb settings.

 

[emdsapmgr]

Re: 1977 115 Hp Johnson that sneezes/spits

A lean sneeze is a carb problem. Esp at idle, when the carb butterflys are closed. The fuel passes through dedicated passages at idle. Small ones. If they get any dried fuel in them, that carb throat can run lean. Maybe miss every few rpm's. Possible the carb cleaner you used during your cleaning just did not dissolve that fuel gel completely. Usually, once the engine is throttled up even just a little other jets supply fuel and it may run just fine. You may need to clean them again.

 

[saltwaterbluefish]

Re: 1977 115 Hp Johnson that sneezes/spits

Thanks for the info. I will dive into it tonight. I am thinking it may be the lower carb since there is a little fuel pooling underneath after running for a few minutes.

 

[emdsapmgr]

Re: 1977 115 Hp Johnson that sneezes/spits

Also, check the airbox drain hose. If it's missing or not connected, that will allow some fuel to pool under the lower carb.

 

[saltwaterbluefish]

Re: 1977 115 Hp Johnson that sneezes/spits

Rebuilt the carbs and found that the gas line running the lower carb was leaking. Got everything rebuilt and tightened and fixed the lean sneeze.

BUT THEN

headed out to try her out on the river. She ran perfect until I tried to give her throttle. I would get about 5-10 mph then try and give her more throttle and she would cut out or run as though she was struggling to get gas to her. One time I did manage to push the throttle to the WOT position, but the motor jumped up speed twice and then died. I did install a new 10 micron fuel filter and new gas lines, also did a pressure test on the lines and they were tight. Also while running the bulb was tight so she is getting gas.

I had this issue last year and after letting her warm up she would finally get up to speed. This issue developed two years ago after having the carbs professional rebuilt (The mechanic just said it was the age of the engine), so I am pretty sure there must be another issue at play beside the carbs.

Any ideas?

 

[emdsapmgr]

Re: 1977 115 Hp Johnson that sneezes/spits

Could be a fuel supply issue. That engine was not made to accomodate a gas/water separator filter. If you are running one, you might try it without that filter in the fuel line. If the fuel pump is weak, you can perform a simple test. Have a friend constantly prime the fuel hose bulb. This will force extra fuel into the carbs. If the engine runs fine as long as you constantly prime the fuel hose bulb, it could be the sign of a weak fuel pump.

 

[saltwaterbluefish]

Re: 1977 115 Hp Johnson that sneezes/spits

I took off the air silencer just to see, and it looks as though the top carb is getting alot more gas than the bottom. Maybe the bottom carb jets are still clogged. Would dipping the carbs overnight in something like this work Berryman? Chem-Dip? Carburetor and Parts Cleaner | Berryman Products

 

[emdsapmgr]

Re: 1977 115 Hp Johnson that sneezes/spits

You can try the product. The bottom line is that you want to know if fuel will flow properly through each passage. The only way is to compare the outflow of one orfice/passage on one carb-with the same one on the other carb. Only way to do that is to blow carb cleaner thru them and visually compare the outflow between the two. If you have a restricted passage you will see it quickly with this method.