1979 Evinrude 25 hp tiller

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PikeSlayer

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Appleton, WI
So I bought an old boat and motor rig from an old farmer who lived near by me. He told me that he ran it up every year, then ran stabil through it and packed it up for the year as he didn't ever have time to take it out fishing. Low and behold, I took it out this weekend to run it up in a garbage can of water and I could not get it to start. I put fresh gas in and I pulled and pulled until my fingers blistered and my arm was sore and didn't get so much as a pop. I called the guy back and finally got the truth from him, that he hasn't run it in 3 years! I'm wondering where to start as taking it to a local marina is probably going to be a pretty decent hit to the wallet. I figured to start by pulling the plugs and making sure they're not all fouled up. I also figure if I can get someone to help me hold the plug against the block and pull it through I can make sure I have spark. What else, if anything, would be good to go through on it? I didn't get any kind of a book with the motor so I'm not sure what else to do with it. Any info or tips would be much appreciated. The motor does pull through so I don't think anything is seized up. Thanks!
 
Probably needs a carb clean or rebuild even. Fuel and spark will be the issues you need to address by the sounds of it. If you have fuel and good spark then you can move on to other possible problems. May want to think about replacing all fuel lines also. Especially if they are original lines.
 
I'm not sure if this is normal or not, but when I pump the bulb until it builds pressure, I can pull the motor through a few times, and if I go to pull the fuel line off the motor, there is still pressure in the line so it squirts out a bit. How else can you check to make sure you are getting fuel to the cylinder? If I pull the plugs and let it dry out, then prime the bulb, pull the choke, and pull it through a few times, there should be fuel in the cylinder?
 
First thing I would do is a compression test, once you've done that and assuming you have good compression, I would think it should be at least 100 psi and within 10% of each other. I would then check my fire, if none we then find out why and fix that, if there is good fire and it will not start, squirt a little premix into each cylinder and see if it will fire, if it does we now have to figure out why it is not getting gas to the cylinders. Been setting 3 years, almost without a doubt going to have to rebuild the carb. Should also replace the water pump impeller even if it seems to be pumping water good, that is cheap insurance.
 
Take the plugs out, hook them up to the ignition wires, use alligator clip jumper wires to make sure that you have the body of the plugs grounded, turn off the lights and in a dark room, pull the start cord, if you see a spark, then proceed to the carb.

Check the vacuum tube that transfers crank case pressure to the carb's pumper diaphram for disconnection or leaks.

Gas dries out, leaving a residue that clogs jets and orifices. Take the carb off and dissassemble it, take pictures of each step along the way so you won't mis-remember how it goes back together. With fine wire and compressed air, clear all the passages. Take care with the pumper diaphram and inspect it for holes/leaks that might prevent it from pumping fuel. You might have to buy a rebuild kit to get the washers and seals that time and your disassembly have rendered unserviceable.
 
I checked online and it looks like I can find a carb kit for less than $20. I can also buy a water pump repair kit, which appears to be all the parts for the water pump, for less than $40. I can also get a whole new fuel pump assembly for about $50. All of the lines appear to be in good shape on the engine itself. Assuming that compression is good on the cylinders, do I just start shotgunning parts at the motor? Or do I try to go bit by bit, start with making sure I have spark to the plugs. I'm still not sure of the best way to make sure I'm getting fuel to the cylinders. I figure if I can at least get it to light off, then I can determine how good or bad its running before I start to throw parts at it. I know things will need to be replaced, and I understand motors need upkeep, but at this point I really want to get on the water. Am I being unrealistic and should I just replace all old parts? What parts would be recommended replacement on an older motor? Thanks guys!
 
I would check compression, then make sure you have good spark, then rebuild carb (and even if fuel lines look good on the outside I would still replace ALL of them if they are original lines, the old OMC fuel lines were not meant to run ethanol and they deteriorate from the inside out. And for around $10-15 bucks for all lines it is a cheap way of eliminating concerns about that. Little tiny black pieces of rubber can clog carb jets easily.) I believe after you do these rather cheap fixes and it still doesn't run you can proceed to other possible problems.

Put some 50:1 mix in a spray bottle and spray it down the carb to start if it doesn't start right away. Then you will know fuel is going through the intake to the reeds. You can also spray a little bit through the spark plug holes to lube up cylinder walls and what not since it hasn't been ran in so long. Thats my 2cents at least
 
I pretty much agree with Johny25, if you just want to hear it run make sure you have fire and squirt a little pre-mix into the cylinders you should at least get a pop. In the end you should replace all the mentioned items even if they seem to be OK. When I go thru an older motor (most of mine are late 50's to early 60's) I replace all fuel lines, do a carb kit, ignition system, etc. One thing I alway fix/replace is the water pump impeller, it may seem like it is working fine and it may for some time but then again it may loose a blade at any time too. Just remember, you might be on the lake and you loose fire or have a fuel issue, most likely the engine will just stop running, if the water pump stops working it may stop running and seize up which is generally not a good thing.
 
Well I've got the carb kit and new water pump on order, should be here next week. I'm still trying to get it to pop off while I wait, and I've so far confirmed spark, and I've traced fuel up to the pump through the filter. I pulled off the air box and I've pumped and pumped the bulb, choke on, and pulled through dozens of times. I'm not getting fuel to the carb. I'll have to keep digging, but I don't know if the issue is that the pump is bad, line to the carb is clogged, or if the valve and float are stuck. Any other tips for this would be appreciated. Thanks guys
 
I guess you could go ahead and pull the fuel line just before it goes into the carb, if you are getting fuel thru it, when you pump the bulb, then you pretty much know the carb is not letting any fuel in. My guess, you will find the needle stuck closed when you open up the carb. Did you try pulling the plugs and squirt a little pre-mix directly into the cylinder to see if she will pop?
 
You were right bb, I pulled the carb off and I could squirt fuel through the line leading to the bowl, but nothing further than that. Once I took the bowl off the needle was shelacked in its guide. I was able to clean it up pretty well. I soaked it all in carb cleaner and flushed it out as best I could. Threw it back together and BLAM, she started right up. Took me a while to get the idle adjustment right. I'll be doing a carb kit on it anyway when it arrives this week. I'm assuming I'll need to adjust the idle setting again. Is there any reason to do anything with the fuel pump if the motor is running fine as is? I found where I can get a new fuel pump, but I just don't know if it is necessary or not. Also, how difficult is it to change out the water pump? I have one coming this week, but I've never changed one before and am not sure how difficult it is. Thanks again guys!
 
Johny25 said:
Probably needs a carb clean or rebuild even. Fuel and spark will be the issues you need to address by the sounds of it. If you have fuel and good spark then you can move on to other possible problems. May want to think about replacing all fuel lines also. Especially if they are original lines.

That is what the first person who commented said to do :wink:
 
You have no idea how old the fuel pump rubber stuff is. It's probably old enough to be allergic to ethanol. I wonder how much of that stuff on my '78 is original???? I'm betting the fuel pump was redone at some point or it wouldn't be working, but who knows about the lines.
 
If you are running alcohol in your gasoline you will be living on borrowed time with your fuel lines and fuel pump (vintage) but you have the option of running non-ethanol fuel or replacing your fuel lines and putting a kit in that pump. There is no additive that will rid today's fuel of alcohol.
 
Carb kit is done, new water pump installed. Checked fuel lines etc... The motor runs AWESOME until I put on the airbox. Then it doesn't seem to want to run right. It runs rich (I think) and when you try to accelerate, it bogs down and dies. I figure there must be something in the air box. There was some mouse nesting material in the bottom of the engine compartment. I can't figure out if there is any way to get inside the airbox to see if it is clean. Is there a filter element inside or can I just blow it out with compressed air?
 
I blew air through the air box and got flow. No debris came out. I can't figure it out. I cleaned the carb initially and I got it to idle well. Then I put in a carb kit and a new water pump, ran the motor with the air box off and it ran and idled perfectly. I put on the airbox and I couldn't even get it to start. When I put the airbox on, the choke lever that hooks to the arm for the choke plate, doesn't allow you to move the choke more than a little bit. When I run it with the airbox off, I can completely close the choke. I've looked at parts drawings and all the parts appear to be right, so I don't get why you can't use the choke properly with the airbox installed. However, now, I cannot get the motor to idle even with the airbox off. It continually wants to die off, but if I flick the choke closed for a split second, the engine will rev back up. I can give it throttle, pop the choke for a second and get it to run smoothly at high rpm. It just won't stay at idle. It also doesn't like to be throttled up from idle to speed. This is a real head scratcher for me. Any advice????
 
I have an '81 25hp with the air silencer like yours. First, lets get the choke lever working properly. The only thing I can think of is when put the air silencer on, its blocking the carb linkage somehow? Also, it can be a little tricky getting the choke lever (#23) mounted correctly. It has to fit correctly with the bellcrank (#1) as well.
Anywho, I know I put it on wrong a couple times, LOL. Take a good look at it again. Also, I think if the choke detent (#43) or choke knob (#21) is upside down, the choke knob may not slide in/out correctly?

https://www.marineengine.com/parts/johnson-evinrude-parts.php?year=1979&hp=25&model=25904R&manufacturer=Evinrude&section=Carburetor

edit: Also, I have a few carb pics, maybe it will help. Let me know if need more.

SDC12594.jpg


SDC12593.jpg


SDC12592.jpg


SDC12591.jpg
 
I cannot get photos to post on here. Is there some kind of a setting I need to change or something? I've got pics of my carb in its current configuration that I want to post to see if there is any obvious issues.
 
PikeSlayer said:
I cannot get photos to post on here. Is there some kind of a setting I need to change or something? I've got pics of my carb in its current configuration that I want to post to see if there is any obvious issues.

They may be too large.
The easiest way is load your pics on a picture hosting website like photobucket, etc.
Then post the image code (or link) in your thread.
 
As far as not being able to get it to idle properly without blipping the choke just richen your idle mixture screw a little bit and it should run start running properly. Turn the screw counter clockwise around 1/2 turn and see how it runs. You may be able to turn it back in 1/8 turn at a time (allowing around 30 seconds for the new mixture to stabilize the engine) and increase the idle quality until it once again shows signs of running lean. Then back it back out a little.
 

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