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1976 Johnson 25hp

S

sdelam

Member
Hello everyone, I have been lurking here for a few weeks and have learned alot but could use some help now.
I bought this motor two years ago and only ran it 1/2 dozen times. I knew the last two owners and knew thay took good care of it but it had sat for about a year when I bought it. New gas and it was good to go. It always worked fine so I didnt mess with it. This year I got a couple new duck holes that have required a boat so I've had it out at least a dozen times since Oct.

A few weeks ago my motor lost all power, it would run fine at idle but bogged down when given throttle. I also had fuel/oil leaking from the water drain hole on the lower unit. I pulled the plugs and the top plug was very wet and fouled, the bottom plug seemed fine. Looking at the coils I noticed the top one was very old, it had cracks etc.. the bottom one looked new so I reasoned that the top one was going bad and that I was likely running on one cylinder.

I replaced the coil and it didn't change anything. Next step was to rebuild the Carb....twice before it would start again...My first carb rebuild. I set the low speed needle to one turn out like the service manual says. I also replaced the gas (the other gas was only 30-45 days old with stabilizer) incase I somehow messed up the mixture. Bought a new hose and cranked it up in the test barrel. Again it ran fine at idle but bogged down above idle. I tried to adjust the low speed needle in and out but 1/4 turn either way killed the motor. I adjusted the little red screw behind the throttle arm, it made the idle higher and after that I could rev it in gear but but it would die when I went back to idle unless I went real slow.

I noticed I had some fuel leaking around the inlet hose on the carb. So today I bought some hose clamps to replace the zip tie. I pumped the hose and it leaked like pretty good. So I loped off the last 1/2 inch and reinstalled it, now its holding. I will pick up some hose next chance I get and replace it completly soon.

Now to the part where I think I need help....while messing with the fuel hose from the ful pump to the carb, I noticed that if I pushed on the fuel pump slighlty it leaked fuel. So my question is...is this normal and if not what seals do I need to replace..and of course could this be my real issue?

Thanks guys!
 
So I got new fuel hose and took it out, ran good at idle while sitting and picking up duck decoys. After the hunt I decided to open her up and check it out. It ran good for 10 minutes or so then I lost power again. Went and bought a compression tester and got 95 on the top and 100 on the bottom. Then decided to check the filters on the fuel pump, screen was good, gasket looked old but ok. So I broke into the pump itself and found that the only metal plate in the thing had bad corrosion to the point where half the diaphram was caked full. Looks like bits maybe breaking off and plugging the carb. Either way I have been running at half strength fuel pump.

So I ordered a new fuel pump, ignition tune up kit, impeller kit, and low speed needle (didnt replace it when I rebuilt the carb). Guess I'll tear the carb down again... will probably save the tune up and impeller till spring. Planed on resealing the lower unit then anyway. Maybe a tell tale mod in the works to while I'm tearing it apart.
 
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water drain hole leaking fuel/oil?????? there is not a water drain hole as far as i know, if you have to drain water out of your lower unit you have a considerable problem. the lower unit oil drain plug(if thats what you ment) should not be leaking oil, and if it is thats how water can get in. the upper and lower drain plug should have a small gasket/ring thats probally bad if anythings leaking from the lower plug.
 
Not the lower unit oil screws, lower unit is good (after I replaced theplug seals). It was the small water drain hole above those, but that seems to be fixed now that I have both cylinders going again.

Just wish I didnt have to wait a week for a new fuel pump.
 
i gotchya, i think its actuall a exaust releif hole but that may not be the correct name. i do know its normal to leak some unburned oil/fuel when you flood the motor trying to start it and then get it running. got any pics of your motor? i love those ol sea horses!!! best small outboards ever made if you ask me.....
 
Here are some as it sits now, sans starter and fuel pump.

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I would like to replace the sticker on the throttle, and the neutral etc sticker. I'll leave the hood decals off for now. Not sure the ducks would apreciate them as much as we do.

I took the sarter off to get to the carb bolts and am awaiting a replacement fuel pump.
 
i see.... yeah they only sell the whole set. you could make a cover out of some camo cloth to sit over it when your filling the sky with steel....
 
Just above it yes, I dont think this motor came with electric start originally. The battery cables are run through two holes drilled on either side of the slow speed knob where the "Lean" and "Rich" used to be. BTW, the starter motor is just sitting there, its not bolted in.

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the solenoid on mine is on the same side as starter, and i forgot he said he had it and the pump off. sdelam, i beleive your right, if i remember right my grandpa replaced the little metal plate where the choke and stop button is with one that has four holes, choke,start, battery cables, and stop button. also different is that mine has a black plastic silencer in front of the carb and to get to the low speed needle you have to remove the motor cover. and i meant what was that black and silver deal on the side in front of your gear switch? if you know your model number you can tell if it origionally had electric start..keep us posted after ya get it back together and good luck!!!
 
The Model number is 25R76E. If you have a link to the decals you mention, I'd be happy to take a look. As a side note, I have to be careful when tilting the motor because of the way I built the duck blind, sometimes the start switch will hit the blind frame and scare the crap out of me when the motor turns over unexpectedly.

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those model numbers i gave ya were off the decal site. have to look at the model year chart to know if it was electric from the factory or not....
 
Alright, finally got my parts in, just a summary of work done to date;
replaced ignition coil, plugs, fuel lines, fuel pump, low speed needle, and rebuilt the carb..again.

Ran it tonight and it started fine but would miss and die after 30 sec's or so. BackED out the low speed from the one turn to about 1.5 before it would stop missing. Seems to run smooth now but maybe idle a bit fast. The video shows it in gear but at idle. Let me know what you think.

CLICK IMAGE FOR VIDEO

 
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50:1 mix...The manual says to start at 1 turn out, but that caused a lean miss. I backed it out to about 1.5 and everything smoothed out. I adjusted it in fwd gear at idle after the motor warmed up 4-5 minutes. The the idle stop screw is on the back of the throttle arm but backing it out any further dosn't help, the throttle wont go that low. I plan on taking it out tomrrow and will play with the mixture then. Thanks.
 
kimcrwbr1 said:
It sounds like your close are you adjusting it in gear fwd. Fuel mix 50:1. turn the idle air out 1 1/2 turns and warm the engine up to temp. If it is idleing high adjust the idle stop the idle is controlled by the timing the stop is either on the throttle shaft going in the lower housing or above the carb I will check on your model. You may nedd to adjust both the idle air and stop screw until you dial it in. Turn the idle air out until it starts to load up then back in until it starts to cut out. Once you get the smoothest lean adjustment turn the idle air out 1/4 a turn and then center the adjustment knob stop to stop. You want to run a little on the rich side to protect the engine while your trolling it needs a little more oil. It needs to be in gear and wait for the crankcase to stabilize after you make an adjustment. I always flush the engine after each use, run it for a bit then disconnect the fuel line and run it out of fuel. Enjoy time to take it out for a good workout.
Click to expand...

100% agree with running a little rich, and out of gas completely after each use. i disconnect the fuel line at the motor right before i get to the dock and let it idle, by the time i get backed up to load her shes dead. my 80 25hp i start with 1 and a 1/4 turn out on mylow speed needle and adjust from there. n ot sure if its been said but after each small adjustment of any type give the motor 15 or 20 seconds for it to react all the way to your adjustments, if you dont youll be chasing the setting you want back and forth and never get it where you want it. at least thats been my experience
 
I took the boat out this morning for a Duck hunt and to play with the mixture. The motor fired right up and ran at high idle for 10 min or so before I pulled it out away from the ramp. It throttled up fine and got us to the spot but when I throttled down it started to miss a bit again and eventually died. I used the trolling motor to put out decoys and then fired it back up to hide the boat again with it missing a bit at idle.

After a pitiful excuse for a duck hunt, I fired the boat back up to play with the mixture. Took a 5 min spin around the lake at 1/2-3/4 throttle to warm it up and then went back to idle but in fwd gear. It did not like goiny any leaner so I started backing it out. Got about 1/2 turn out (in small increments, waiting for the motor to respond between adjustments) and then it started bogging down. I turned it back in maybe a 1/4 turn and it idled nice and ran good.

I'm thinking "Great! I got it" but when I pulled the boat out of the water I had fuel/oil leaking from the "drain" hole on the lower unit again.

I guess I'll lean it out a bit more and deal with it missing after throttling down. I guess...any ideas

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I pulled the thermostat and checked in a pan of water, it started opening around 140-145 and was full open by 160ish. removed from heat and it closed fully around 145ish.

However it did bring up another question. I noticed that the seal was not installed per the picture I found on the net, here is the contrasting pic's. Bottom is what mine looks like, top is from internet. Which is correct or does it matter?


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I don't think I've ever ran the motor for an hour, lol. I actually have cleaned up the prop some, it was pretty rough. I didn't think about it being left over from before I adjusted it. Thought that would have cleared out on my way back to the ramp.

Taking it out again tomorrow but it will be pretty shallow lake so I won't be doing any WOT. thanks guys
 
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