84 Johnson 40 HP Weak Top End/No Slow Idle

[racerone]

Parts should not be hard to get !-----Most motors rev right up in neutral.---It will rev on one cylinder !----A V-4 will rev right up on 2 of 4 cylinders !------That proves nothing at all.

 

[foreman05]

These were brand new before our fishing trip today. The top one definitely has some oil on it or fouling. The bottom one doesn’t even look used.

 

[racerone]

See post #2 in this saga.

 

[foreman05]

See post #2 in this saga.

Not sure what your problem is but I’m not making you read this am I?

yes, thank you for post #2 like I said earlier, advice followed. Spark check, it is sparking although it’s more of a red spark than blue.
compression check, yes 130+

 

[racerone]

Some want to know.----Does spark jump a gap of 3/8" ( 1 cm ) on a test device , yes or no ?

 

[tphoyt]

That bottom cylinder is clearly not firing.
Before you check your spark with an adjustable spark tester get some oil into that cyclinder even if it’s just WD 40.
If it’s not getting fuel it’s not getting oil.
Damage to that cylinder is not far behind if it’s not already been done.

 

[foreman05]

Sorry tphoyt, didn't see your post until after I checked it.

Yes it has spark on both cylinders, it will spark at 3/8".

I will also spray some WD in there. Could we assume with strong spark and a clean spark plug maybe its not getting fuel to that cylinder?

I am going to get new wires, these don't make the most positive connection.

 

[tphoyt]

If the plug was dry then most likely it’s not getting fuel. I really think you would benefit from a complete carb job. The kit are cheap and readily available. Finding parts is not going to be a problem.

 

[oldboat1]

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ww2.iboats.com

Disassemble your carb and soak all metal parts in solvent (separate the top from the bottom of the carb, and soak both without removing linkages. Remove the aluminum plug on top before soaking in order to open idle passages. I would leave low speed and high speed jets in place for soaking. Use carb cleaner to blow through to make sure the passage is open. Finish carb cleaning by blowing carb cleaner through every hole you can locate, and replace the aluminum plug (compression fitting) with on in the carb kit for your motor. Get the kit with a replacement float. Make sure to use gasket 7 or the carb will not draw properly.

 

[foreman05]

Will do,
I just order this kit

https://www.amazon.com/dp/B000XBKNCQ?psc=1&smid=ATVPDKIKX0DER&ref_=chk_typ_imgToDp

I also added a fuel pump because why not. I will pull off all the fuel hoses this week and get new ones, doesn't seem like there any hose sets to buy.

Thank you all for all the feedback on this!

 

[foreman05]

Well to let everyone know the outcome.

I picked up a new fuel pump and two carb rebuild kits and had them installed by a boat guy. Figured this was better in case the issue want just refreshing the carbs. During the carb rebuild he noted the brass line from the carb bowl was almost completely clogged.
After rebuilding he said it still wasn’t perfect so he ended up rejetting the carbs and replacing all the old fuel lines.

now the beast is tearing up the water! I was able to get it to 28 mph with just myself and 25 with my whole family in it. Super impressed and thankful it wasn’t a major repair.

thank you all again for your help and advice on this!