25 hp Johnson stalling out

newbeewhaler

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Need Help from some experts.


Finally took out a 25 hp Johnson in the ocean today. After cold starting her on muffs at the house, we drove the 13' whaler down to the boat ramp. Launched her, fired
up the outboard no problem. didn't warm her up to long (Less than a minute warm up).
Then started cruising towards the channel. Just crusing real slow using the channel cruise as a warm up time. Accelerated a bit to test her and she felt like she wanted to plane out :) so I was happy and went back to cruise and let her warm up.... That's when a 24' whaler was flying back in to the ramps, in the no wake zone and created a huge wake that hit us.
So we want to get some speed after going over the first wake because we were getting knocked around and as I try to accelerate.... the motor dies. Try to start her up again quickly as were in the channel, and winds are blowing us off of channel into shallow reef that could damage the long shaft. :eek: Start her back up and try to accelerate to get some speed and again she dies. :mad: start her up again and , she can only barely idle and any acceration in the throttle caused the motor to die out. Ok. decide to turn around back to ramp. :( Not even one minute out to sea. Head back to the ramp. We tie her up and take off the cowling and try to play with the air/fuel mixture. But can't figure her out. Decide to take her up the ramp and put the muffs on to test her. Well the muffs weren't tight enough so she wasn't peeing. I thought the water pump was bad so took her home. At home she was peeing, so not the water pump...:confused:

My question to any outboard mechanics out there is: What is going on here. Did we not warm the engine up long enough? Is the oil/fuel mixture slightly off?
 

Cofe

Lieutenant Commander
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Apr 23, 2009
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Re: 25 hp Johnson stalling out

Sounds like a dirty carb to me.
What year is your 25? Older fuel lines sluff off particles of rubber that can restrict or plug passages in the carb.
Your motor needs 50/1 fresh fuel mix.
 

kfa4303

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Re: 25 hp Johnson stalling out

Hi newbeee. It's good that she stars and runs on muffs, but I'm thinking it needs a carb cleaning/rebuild, but samo is right. We need a model and year to know what carb kit you need and what fuel:eek:il mix you should be running. Look on the transom clamp and see if you can see an ID tag riveted on there. They're usually on the left hand side.
 

newbeewhaler

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Re: 25 hp Johnson stalling out

Thanks guys


1998 Johnson 2 Cycle 2 cylinder

yes 50:1

Changed spark plugs recently as the older ones were worn. (By the way ran like a champ with older ones)

Compression check on both cylinders were pretty good. don't remember exactly. something like 120 and 110.

decarbed with seafoam. Ran like a champ last time.

I changed water pump, impellar, Lower unit oil was changed as well.

Been trying to baby her. Only thing I can think of is the fuel/air mixture screw was not quite right.
 

newbeewhaler

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Re: 25 hp Johnson stalling out

also bought new fuel line and bulb with connectors. to connect from 6 gallon tank
 

AlTn

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Re: 25 hp Johnson stalling out

if it ran like a champ last time before you replaced the fuel line and connectors, I'd suggest you go back and recheck that work...is the fuel filter in the tank clean?...is the tank vent open completely?
 

Haffiman

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2,454
Re: 25 hp Johnson stalling out

My guess is that your float/needle valve got a 'kick' and stuck.
Might be solved by tapping the carb, might need to pull it down and check.
 

alumachris

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Aug 16, 2010
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Re: 25 hp Johnson stalling out

could be something as simple as making sure the fuel tank is properly vented. confession: i've done it a few times.
 

newbeewhaler

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Re: 25 hp Johnson stalling out

Thanks again guys!!! Ya, had the vent open in the 6 gallon plastic fuel tank. almost 100% sure of that.

and have never checked the filter in the tank though. Will try to do that, then if no luck I guess I will have to take the carb apart, which will be a first. haha :)
 

newbeewhaler

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Re: 25 hp Johnson stalling out

Thanks AITn, checked fuel filter in the 6 gallon gas tank. Looks clean.
Also. roger that. on open tank vent . 99% sure it was open.
 

newbeewhaler

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Re: 25 hp Johnson stalling out

Right on Haffiman. sounds feasible. Do you mean that when the motor got tossed around in the water, it got stuck?

Tapping the carb? Sounds simple, do I need to take it apart? and clean or rebuild? Never done a carb before.
 

Haffiman

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Re: 25 hp Johnson stalling out

I would have pulled it down and checked. A complete rebuild is probably not needed, perhaps a new needle valve and float height and drop adjustment. Just be sure you have new gaskets.
 

newbeewhaler

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Re: 25 hp Johnson stalling out

Thanks Haffiman.

The last time she ran like a champ was several months ago, I just read that gas now a days starts to go bad in 30 days. I treated the gas with stabilizer and some seafoam, however It has been several months and maybe some older gas just went bad in there. Note to self. When you flush your motor out after boating, disconnect the fuel line to motor to burn out all the old gas so none of the bad stuff stays in there in case you don't take her out for a few months.
 

newbeewhaler

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Re: 25 hp Johnson stalling out

Took out new spark plugs and they are all fouled up and black!?? Also did compression check again, 110 and 100

Anybody know why new plugs are all dirty so soon? I sanded them down cleaned up. Poured some seafoam in the cylinder to try to clean out any carbon in there.
 

Haffiman

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2,454
Re: 25 hp Johnson stalling out

If carb has flooded due to a stuck open needle valve, quite normal.
Never 'sand' plugs unless you want to sand-hone your cylinders and pistons later when you start.
 

newbeewhaler

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Re: 25 hp Johnson stalling out

yikes. I already did it. I'm taking the out tomorrow morning. How should do you clean plugs so that no sanding residue is left on there. Don't want them contaminating the cylinder!!!
 

Haffiman

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Re: 25 hp Johnson stalling out

Just clean (no oil) fuel or carb cleaner, then let dry before installing.
In the 50's they had special sand-blasting cabinets for plugs - until they discovered what happened!!
 

newbeewhaler

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Re: 25 hp Johnson stalling out

Ok, cleaned plugs, engine still coughing and wanting to stall when throttle opened. When stalled out, hard to start again, have to wait before it will start again.....

this sounds like I have to clean out the carb? So my question is... if I have a 1998 25 HP Johnson, the Carb Kits only go up to 1995. Will this (up to 1995) year work for a 1998? If yes, I'll order that one..

Thanks
 

JDusza

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Apr 21, 2009
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934
Re: 25 hp Johnson stalling out

Don't count on it! There's more than one carburetor to choose from depending on your engine model.

Check out bestboatparts.com to get the Johnson part number. This is the BRP site. You do not have to log in. Click through Evinrude/Johnson until you get to "BRP Parts Catalogs". Click on "View Parts Catalog". Next screen, "Select Products", pull down menu to Johnson. Find your year, your horsepower and match to your model number. Model number is found on a tag on the engine's mounting bracket or on a Welch plug on top of the engine.

For example: 1998 25 hp model BJ20SRLECB: select carb for model 20SR: carb kit part number: 0396701.

Now go to ishopmarine.com and plug in part number 0396701 at the top of the page. Three brands to choose from; BRP $24, Mallory $19.89, or Sierra $20.02; all before shipping.

Good luck!
J
 
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