74 johnson 2 hp wont run below 3/4 throttle

Driving me nuts !! I run high test gas with synthetic oil 50 : 1 mix> Engine completely dies when you lower throttle below 3/4 position. tried the jet adjusting new line cleaned carb thouroughly twice. Even switched to an electronic ignition module, still no better. I had it run smoothly once and once only ?? I do notice the coil housing or cover has a crack from age or heat or??? but I didn't think this would be the problem seeing that at full throttle the engine runs flawlessly. I know everyone want's to say low speed adjustment but believe me I've tried that a hundred times. It just completely dies very suddenly when you throttle back??? I even drilled two of the four exaust holes bigger in hopes of allowing the engine to breath a little better.

Re: 74 johnson 2 hp wont run below 3/4 throttle

Cleaning the carb does not mean the carb is clean, Jay.

The smaller the engine the smaller the jets and tiny orifices that feed gas into the carb throat at low speed. Only when you target them specifically are you likely to get them clean.

Look in the carb throat. At the bottom of the throat, just about where the throttle plate touches, there are (usually) two tiny, tiny orifices. You can get best access to them by removing the plug opposite them (There are replacement plugs in the carb kit), but I usually bend a small wire into an "L" and poke it through from the end of the throat.

Good luck.

Re: 74 johnson 2 hp wont run below 3/4 throttle

i do the same. on all my carbs, , but I usually bend a small wire into an "L" and poke it through from the end of the throat. i use a small paper clip.

Re: 74 johnson 2 hp wont run below 3/4 throttle

OK OK I got it ! I will try another carb cleaning and see what happens. I know of the tiny tiny passeges you speak of and maybe they or one of them has become plugged. I will let you guys know later today. Thanks for responses guys

Re: 74 johnson 2 hp wont run below 3/4 throttle

JB said:

Cleaning the carb does not mean the carb is clean, Jay.

The smaller the engine the smaller the jets and tiny orifices that feed gas into the carb throat at low speed. Only when you target them specifically are you likely to get them clean.

Look in the carb throat. At the bottom of the throat, just about where the throttle plate touches, there are (usually) two tiny, tiny orifices. You can get best access to them by removing the plug opposite them (There are replacement plugs in the carb kit), but I usually bend a small wire into an "L" and poke it through from the end of the throat.

Good luck.

Click to expand...

Thank you Thank you!!!!!!!! actually there are three tiny tiny holes and I used the bent wire and then liberal amounts of brake parts cleaner. After that I used a rubber tipped blow gun and blew compressed air through the low speed needle port. A littli patience adjusting the needles and she runs fine fm idle to full with no problems. Thanks again for the replies, I've learned some valuble info once again.

Re: 74 johnson 2 hp wont run below 3/4 throttle

Thanks for the report, Jay. Too often we offer advice and get no feedback about whether it worked or not.

Knowing that it worked makes my day.

Re: 74 johnson 2 hp wont run below 3/4 throttle

Also, remember that in your first post, you said one of the coils was cracked. If it's not bad now, it probably will soon be. If you lose spark on one of the cylinders in the future, that'll be the place to look.