50 HP johnson wont open up

mstrud

Seaman
Joined
Dec 5, 2007
Messages
72
I have a VJ50TLETB on a 20 foot pontoon. I hadn't taken it out in a few months, but did the other day with a few friends. It fired up fairly easily for having sit for a few months i was actually a bit suprised at that. Upon launching it though I was suprised at the dock when the fast idle lever was all the way up it just didn't sound like it was reving as high as it used to. Predictably when underway with the throttle all that way down she wasn't whinning like usual. I dont have a tach but estimate her top end to be around 2500-3250 RPM. The boat was pretty heavily loaded but it's propped for those conditions. I know it's running on both cyl as its only a two cyl when one fails (and has in the past due to a faulty 'new' powerpack) you can definatly tell and it wont get above a rough half idle, that and there was no sign of unburned fuel so I'm pretty sure all is well ignition wise. I've redone the entire ignition system before, actually just short of a engine rebuild, and carb rebuild I've done everything to the motor that I possibly could have. My question is... Is this lack of get-up-n-go indicative of needing a carb rebuild? I've ordered the carb rebuild kits as I'm guessing that this is what it has to be, but just wanted to see what the old salts have to say. Your opinions please...
 

mstrud

Seaman
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Dec 5, 2007
Messages
72
Re: 50 HP johnson wont open up

yeah, that's all well and good. Could you just answer my question about 'will clogged carbs cause this to happen' the 1 in a million things like, the flywheel slipping (as assinine as that sounds because there's a groove on the crank shaft that the FW slides onto to keep such a thing from happening and to assure correct timing sequence) or levers not advancing ought to be saved for desperate 'what ifs'. If this isn't normal behavior of carbs that need a rebuild... state that, then feel free to ad advice on top of that. I'd just like an answer to the question I posed, not answers to questions i didnt ask.
 

mstrud

Seaman
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Dec 5, 2007
Messages
72
Re: 50 HP johnson wont open up

one more peice of follow up. Everything on the motor is as it should be. ie cables work, things move when needed to etc... the improbable stuff isn't an issue.
 

james williams

Petty Officer 2nd Class
Joined
Jul 22, 2006
Messages
105
Re: 50 HP johnson wont open up

Are you positive it`s got spark on all three cylinders. hope this helps..james
 

5150abf

Vice Admiral
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Aug 12, 2007
Messages
5,808
Re: 50 HP johnson wont open up

Concur, one or more carbs are dirty.

You will want to fix this before you run the boat again, no gas, no oil, and it doesn't do your crankshaft any favors either to have a dead cylinder.

I have used a dental syringe(CVS pharmacy) to squirt a little gas into each carb until you find the one that is dirty although I really recommend you clean them all.

Do them one at a time and mark them so you get them back on the engine right and keep the jets with the cover screw so you don't mix them up and work on a piece of newspaper, a cloth can leave lint.

Use a stranded copper wire to clean the jets, just pull back strands till it just fits , run it through a couple times and you are good, also make sure you run a wire through the passages between the idle and mid jet and use compressed air to blow everything out, the "air in a can" for your computer works well.

Last but most important, get an OEM manual(not clymers/Seloc or CD)here at iboats, it Will pay for itself immediately.
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,758
Re: 50 HP johnson wont open up

While you are asking one single question, people are trying to help you with other ideas. Here are some more things that can affect operation. Bad gas (you said it sat for a couple of months). Do you use a fuel treatment like Stabil or SeaFoam? Did you actually pull the plugs and check them? Water in the fuel? If you live in area where regular grade gas is an ethanol blend that can be an issue with long term storage. You may simply have a float/needle and seat that is stuck shut and not allowing fuel into one carb. But to answer your question, yes -- gummed up carbs can cause this issue. That doesn't mean that should be the first thing you should dive into.
 

mstrud

Seaman
Joined
Dec 5, 2007
Messages
72
Re: 50 HP johnson wont open up

alright thanks guys. Getting back to one of the replys, it's a 2cyl engine so a dead cylinder would make it run totally different so I know it's not that. Glad to hear that remark about the high speed nozzles being glogged, that's reassuring, I dont intend to run it again until I at least have the carbs rebuilt, I've had a motor in the past loose all compression in a cyl from something like that. I'm a little worried now that I did run it the last day i took it out, I hope I didnt burn a cyl from an hour of running it with one or more cloged carbs. **** well I'll do a compression test when i redo the carbs and pray both cyls are still 145ish. In the future now I know and if the same happens again I know not to push it to full throttle bc of risk of burning a cyl. from a lean mix. damnit what was i thinking...
 

tashasdaddy

Honorary Moderator Emeritus
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Nov 11, 2005
Messages
51,019
Re: 50 HP johnson wont open up

good luck, let us know what you find.
 

mstrud

Seaman
Joined
Dec 5, 2007
Messages
72
Re: 50 HP johnson wont open up

stuck needle. really stuck, i knew that had to be it when i took off the drain plug and absolutly no gas came out, im glad its only a 2cyl and was capped at 2500 rpm, othewise im sure the hour i ran it would have been more deterimental with a 3 cyl that could still rev a lil higher on 2/3. ill check compression tomorrow and let yall know what running an hour with no gas can do to a cyls compression.
 
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