1967 johnson 20hp fd21r need help

[@bebeslife4519]

Okay I have a similar motor and I think I know what the problem is likely. So at idle, the carb roller needs to be fully closed. That will richen the idle mixture. If it is slightly open or if you pull the butterfly with your finger, you are bypassing the timing and just making the motor run lean. This will cause that coughing condition. The next thing would be the top crankshaft seal! On these years 18-25 OMC motors, the top crankshaft seal likes to leak on heavily used motors. That will cause a poor idle quality no matter what you adjust. If the engine runs for a few minutes and dies, but starts right back up again, you know the fuel pump is working. Happy tinkering!

[@donk499]

These carburetors have a strange design. The low speed needle threads into an aluminum sleeve which is just pressed into the carb body. Holding the sleeve in place requires that the packing nut be tightened enough to secure the threaded sleeve. So, when you think you are turning the needle valve, you are actually turning the whole sleeve in the carb body, so the actual low speed needle adjustment is not changing...

[@tonywright510]

Make sure your coal wire is not Arc in at the coils

[@marioflavin2141]

Sounds like its shorting out somewhere.

[@TheFrogfeeder]

The sweet spot is usually(but not always) between 1 turn out and 3/4 out, you get there by turning clockwise in small increments from that 1.5 turns out starting point. And give about 15-20 seconds for the motor to respond to each adjustment.

[@kimchua9939]

Same thing happened to my Johnson 40hp 1972. Check the low speed needle point at the end. Also 3 tiny holes below low speed needle. I soaked the carby with carby cleaner but still didn`t work..! By the end i used vaccum cleaner to suck out all shit inside low speed needle hole. The motor run very strong and smooth. The low speed needle 1.5 turn out.

[@TEKKKNO]

Check the retainer seal on the needle maybe it sucks air from the idle needle

[@TheFrogfeeder]

the 1.5 turns out is already a RICH mix. You supposed to LEAN from there. Here’s how you do it... turn the needle all the way clockwise till lightly seated, back needle back out 1.5 turns counterclockwise, start motor and let warm up for a minute let it cough it’s fine, turn needle CLOCKWISE to lean out from there. Lightly seated means fingers not pliers. You are going WAY TOO RICH by keep turning the jet needle counterclockwise, you need to LEAN IT OUT from the starting point. Use very small fractions of a turn. Keep LEANING the motor out, in small increments, until you find the sweet spot where the rpms are solid and it don’t cough. Your cough is 100% that needle being turned the wrong way from the starting point of 1.5 turns out from lightly seated. That needle...turning to the right(clockwise) restricts more fuel, turning to the left(counterclockwise) lets more fuel in...at 4 turns counterclockwise you might as well not have a needle restrictor there at all, you just dumping fuel into the motor... I know it’s been a long time, but that is 100% your problem, you are adjusting the needle the wrong way...

[@TheFrogfeeder]

With these old motors, 95% of the time 95% of their problems are fuel related. It’s good you changed all them other parts trying to chase down this cough, but I have never had a motor that NEEDED new parts u dear the flywheel, maybe if they been in saltwater those parts would be compromised over the years... I do replace those parts sometimes, but really I think that stuff is rarely the problem, it’s all so simple it has to work... Always remember, a cough in a motor at idle means too rich.

[@ACDC5540]

Vacuum leak

[@K3NN3DY102]

You sure model number is fd-21r? I can’t find electric start setup for mine

[@seniorLu48]

Did you ever find the issue with your motor? I had one not like yours and it was the fuel tank vent needed to be cracked open.

[@gregpeel1212]

supposed to be a metal rod runs from there

[@WeAreINEndTimes]

Hello Sir......I have the exact same motor as yours and it is doing the very same thing as yours. I realize this is an old video but i am at a loss here just like yourself!! Did you every find the problem? I have looked the web over and cannot find another motor doing what ours are doing. Please sir if there are any way you can help me I sure would appreciate it. Any advice at all would have to help. I cannot figure this out. Thanks in advance...

[@marcus123841]

Link and sync is your problem

[@bradleygreer9211]

Push the choke in

[@taylormorgan2774]

Did you ever get that boat motor going?