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trouble with 1993 Johnson 25 hp


paradiselost69's Avatar
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Join Date: May 2010
Posts: 4
NY

05-06-10, 03:45 AM   #1  
trouble with 1993 Johnson 25 hp

I just bought a boat and motor from my neighbor who used it very little. I'm not sure if it needs a tuneup or just a little knowledge in how outboards run. I have had two boats before, each with I/O drives and large gas tanks and no priming. I replaced all of the gas and spark plugs on the motor. I have trouble keeping the motor running and have to keep pushing the choke button in and furthermore the primer does not stay hard. I'm not sure how old the fuel tank and connecting hose are so I am wondering whether to just flat out replace these items for a starter. I have never done any small engine repair and I have no manuals on either this 25hp motor or the extra (fairly new 2hp Johnson). There is also a twist knob below the start switch and I am not sure what that does. The boat is a Discovery Voyager 16 feet. the shift mechanism has OMC on it. I have a side mission right now - while attempting to tighten the existing start switch which was loose, I broke it and will be getting a replacement today. I think the package was a good deal but right now I am a bit frustrated trying to figure out and get things working properly. Any help would be greatly appreciated.

 
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Legal v8's Avatar
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Join Date: Sep 2007
Posts: 239
MN

05-06-10, 03:59 PM   #2  
Posted By: paradiselost69 I just bought a boat and motor from my neighbor who used it very little. I'm not sure if it needs a tuneup or just a little knowledge in how outboards run. I have had two boats before, each with I/O drives and large gas tanks and no priming. I replaced all of the gas and spark plugs on the motor. I have trouble keeping the motor running and have to keep pushing the choke button in and furthermore the primer does not stay hard. I'm not sure how old the fuel tank and connecting hose are so I am wondering whether to just flat out replace these items for a starter. I have never done any small engine repair and I have no manuals on either this 25hp motor or the extra (fairly new 2hp Johnson). There is also a twist knob below the start switch and I am not sure what that does. The boat is a Discovery Voyager 16 feet. the shift mechanism has OMC on it. I have a side mission right now - while attempting to tighten the existing start switch which was loose, I broke it and will be getting a replacement today. I think the package was a good deal but right now I am a bit frustrated trying to figure out and get things working properly. Any help would be greatly appreciated.
If this was my boat, this is what I would do:
Replace all fuel lines and primer bulb. Especially if it didnt get used much.
Replace spark plugs with what the MFG. recommends gapped to what they recommend.
Check spark - blue or purple is good, yellow or orange isn't good.
Try running the engine. If it still won't run off choke, then clean out the carb and blow out with compressed air. Install new carb kit w/ float and gaskets.
Run engine again. By now, if you do all of this, it should run like a top.

Again, this is what I'd do if it were mine.
Oh.. and that knob you're talking about.. I'd guess thats idle mixture. Counterclockwise goes rich and Clockwise goes lean. This would be something to adjust after replacing the hose and primer bulb. With the engine stalling with the choke off, try richening the mixture. If you max the knob out and it still won't run right, then I'd jump to the carburetor.

 
paradiselost69's Avatar
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05-06-10, 04:29 PM   #3  
Thanks, Legal. I bought a new fuel line with bulb today in anticipation of this. I also have the new key switch. The weather has turned colder again here in central new york and the wind has picked up. Since the boat is in the water (beached at my campsite) I will wait a couple of days until it gets warm enough to feel comfortable standing in the water while I work on it. I'm nervous about rebuilding the carb but I imagine if I go slow it will be ok. Thanks again. I will post when I have something new to report.

 
Legal v8's Avatar
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05-06-10, 08:29 PM   #4  
Posted By: paradiselost69 Thanks, Legal. I bought a new fuel line with bulb today in anticipation of this. I also have the new key switch. The weather has turned colder again here in central new york and the wind has picked up. Since the boat is in the water (beached at my campsite) I will wait a couple of days until it gets warm enough to feel comfortable standing in the water while I work on it. I'm nervous about rebuilding the carb but I imagine if I go slow it will be ok. Thanks again. I will post when I have something new to report.
Small outboard carburetors aren't that bad.. If you've never been inside of one, (or any carb for that matter) it can seem like a daunting task. If you have some mechanical knowledge, you can get the job done. If you do a little looking around, you should be able to find a diagram of your carburetor to go off of for reference. Another thing you can do is if you have a digital camera, snap pictures part by part on disassembly and just look at them in reverse to put it back together. See if you can find the model number on the transom bracket and I'll see if I can find a diagram for you. (or if one of the mechanics has one handy they could scan and post..) Since its a Johnson 25, I'm guessing its going to start with J25. I have a clymer manual for all early 90's Johnson/Evinrude outboards but I don't know if it has carb pictures in it or not. I'll look tomorrow.

 
samuari's Avatar
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05-06-10, 09:33 PM   #5  
Legal summed it up nice so I will just add that it's normal to have to choke it to start and may need to hit the choke a couple times before it worms up. Also the primer bulb may not stay hard, when it's hard it because it's putting pressure on the needle and seat of the carb. Once it's running the fuel pump will take care of regulating the pressure.

Good luck with it.

 
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NY

05-26-10, 02:15 PM   #6  
I had a friend come over before I bought the rebuild kit for the carb and he found an idle adjustment that I did not know about and once he tweaked it, the motor started running fine and no longer stalled. So now my two gas motors are running great but the MinnKota trolling motor has stopped spinning. It is a bow-mount with foot pedal. it rotates left and right but only clicks when I push the "go" pedal. I checked all the wires for continuity and they are good. There is a sealed circuit board with a relay and transformer. I hear the relay clicking and discovered that the 12volt ground is not switching when the pedal is pushed. I jumpered the two grounds together and I can get full speed and left right turning. I am guessing that I need the circuit board at $75 but would like encouragement before I spend this much.

 
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05-26-10, 03:27 PM   #7  
I just talked to tech support at Minn Kota and they say the circuit board is the most likely candidate, so I ordered one.

 
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