Fuel only making it to one cylinder Johnson 9.9

[Jmac870]

So I discovered the other day a cylinder was not firing on my 76 Johnson 9.9 and after some tinkering around realized the top cylinder is not getting fuel. I took the carb off yesterday and cleaned it to the best of my ability (new to working on motors) and did spray a bit of carb cleaner into intake manifold before I put the carb back on. Fired the motor up and it idled beautifully for about 30 seconds before it lost the top cylinder again and started whooshing a coughing big burps of exhaust out of the prop. Question is if my carb is clean and other cylinder getting enough fuel to run the motor. Could something be clogged up in the intake manifold that's not letting fuel pass to top cylinder? Thanks in advance for any advice

 

[tblshur]

Jmac870 you might try spraying some premix in top carb if it smooths out some maybe still something in carb good luck :joyous:

 

[Chinewalker]

The carb feeds both cylinders equally. If one cylinder is getting fuel properly, the issue is likely NOT the carb. Other things that might prevent fuel delivery to one cylinder and not the other - a worn upper main seal (under flywheel), broken intake reed, obstruction in the intake plate, low compression in upper cylinder. No much else it could be.

Which begs the question - are you SURE it's a fuel issue and not ignition? Have you done a compression check? A proper spark check?

 

[Jmac870]

I have checked compression and both cylinders read right about 90PSI give or take a couple PSI, the top cylinder has a brand new coil on it and new plug as well, while I haven't measured the distance the spark will jump it is for sure 7/16. I'm not sure if pulling the flywheel is something I'm really equipped for tool and knowledge wise and unfortunately. I guess one thing I have not done is tried switching the coils because I kind of assumed it being brand new was working properly.

 

[Jmac870]

Is water getting in the cylinder somehow a possibility?

 

[Chinewalker]

Check the plugs for evidence of water - water droplets should bead up on an oily plug electrode...

 

[Jmac870]

That may not be my issue then I switched the plugs back and forth and ran the motor a couple times to see if the other plug came out clean but it did not and I could not see any water droplets

 

[Bosunsmate]

You should light it to make sure its fuel. Ive had plugs looking wet with fuel but wouldnt burn as water was actually on it too but not discernible.
Swap your carbs over, then you know if its carb problem.
Have you tried a bit of paper held in front of carb trick?

 

[Vic.S]

You should light it to make sure its fuel. Ive had plugs looking wet with fuel but wouldnt burn as water was actually on it too but not discernible.
Swap your carbs over, then you know if its carb problem.
Have you tried a bit of paper held in front of carb trick?

Its only got one

 

[Vic.S]

deleted

 

[racerone]

A broken reed valve does not show up on a cylinder compression test.--The reed valves have to do with compression in the crankcase.-Totally seperate things.

 

[Jmac870]

So to check the reed valve what would I go about doing? Would the flywheel need to come off or can I remove intake manifold? I am not the most mechanically inclined person and part of the the reason I bought this motor that needs work is to try and gain some mechanical knowledge so please bare with me if some of my questions are amateur.

 

[Jmac870]

Also, when looking at the parts list for the intake manifold there is a "Leaf valve" listed, states I need 2, im guessing this is another name for the reed valve or am I mistaken?

 

[Vic.S]

You guess correctly

 

[Jmac870]

So to check the reed valve what would I go about doing? Would the flywheel need to come off or can I remove intake manifold? I am not the most mechanically inclined person and part of the the reason I bought this motor that needs work is to try and gain some mechanical knowledge so please bare with me if some of my questions are amateur