Billhein94
Member
OK. . I'm going to make a short story long in hopes that somebody can make some sense of what I have been doing.
Earlier this year I bought a 14 foot boat and trailer with an Evinrude 25 HP (ended up being a 1975 25502B). I took it out and it started up just fine. It ran good, but WOT didn't seem like it should. RPM's seemed low and wasn't as much power as I was hoping for. I also notice that it had a hard time idling. . like it would die when I cut the throttle. It would start right up again, but I would have to give it some throttle to keep it running. I also noticed a significant amount of fuel/oil in the water. I took the hood off to look at stuff and when I went to take the spark plugs out, I noticed 2 things. 1: The plugs were dark and wet, 2: the bottom plug was not connected. So....I connected the plug thinking that the fuel in the water was from unburnt fuel from that cylinder. I ran it the rest of the year like that. Still seemed low on RPM's still not as much power and still not idling very well still fuel in the water, but it was manageable.
This fall, I decided to rebuild the carburetor to hopefully clear these issues up (I am not a mechanic and have never done anything like this before) After watching videos and reading forums I felt I had a pretty good grasp and it was also recommended that I rebuild the water pump as well. So I rebuilt the carburetor, with the kit from this site. I did notice that the slow speed needle was out way further than it should be like 5 or 6 turns. Knowing what I know now. . there is a good chance that was the major cause of all my problems. When I put everything back on I also noticed that the butterfly valve for the throttle was not opening all the way at WOT. So, I lined up the cam follower with the end of the biggest lobe (which should be WOT) and adjusted the linkage so the valve was completely horizontal. I do have a service manual, so I followed it to link and sync the throttle with the 2 lines. I also replaced the impeller on the lower gear unit and put in all new fuel lines.
I got it started, but it was running even more rich than before I couldn't even keep it running. There was a lot of fuel in the barrel that I was running it in. It was recommended that I take a look at the fuel pump, so I just went ahead and put in a new one. Things improved with the fuel pump and I was able to start it and keep it running. I was able to make adjustments with the slow speed needle and could hear changes in the engine. I could put it in gear and increase the throttle but it would seem to sputter. I checked the spark, but it was with a cheap tester that just shows a light if there is spark or not. When I checked it I noticed some spark coming from behind the bottom coil, almost like it was sparking to the engine block.
Oh yeah. I have a 1973 18HP that has a lot of compatible parts as well. .. so, I took the a coil from that to fix the spark problem.
So, where I am at now. . I can get it to start pretty easy and it will run, but I am still seeing a lot of fuel in the water and the plugs are still wet and black. I did notice a small pool of fuel at the front of the carburetor (not sure if that is normal) and also when I put the carburetor back in from the rebuild it looks like I might have pinched the vacuum line the is back there. (I'm not sure what that does....fuel pump?) My next step in my head is to change the points and condensers with the thought that I don't have enough spark and unburnt fuel is coming out of the exhaust and showing up in the water. I am hesitant to take off the flywheel because I really don't want to mess with the timing. I was also thinking that the reed valves may be at fault and the 18 HP motor has the same part number. So maybe between the 2 motors I can get one good one! Another thing to note, I have been able to start it without using the choke and that leads me to believe that is still pretty rich.
Also, the idle screw is missing, so I could be going to far and allowing the RPM's to go too low, maybe that is the cause of my idling woe's. I have an RPM indicator on the way and I plan to get that part figured out then I can make other adjustments.
It really didn't run that terrible before I started tinkering and I am afraid I am making it worse, but I don't think I have ruined anything yet?? Am I on the right track here?
Earlier this year I bought a 14 foot boat and trailer with an Evinrude 25 HP (ended up being a 1975 25502B). I took it out and it started up just fine. It ran good, but WOT didn't seem like it should. RPM's seemed low and wasn't as much power as I was hoping for. I also notice that it had a hard time idling. . like it would die when I cut the throttle. It would start right up again, but I would have to give it some throttle to keep it running. I also noticed a significant amount of fuel/oil in the water. I took the hood off to look at stuff and when I went to take the spark plugs out, I noticed 2 things. 1: The plugs were dark and wet, 2: the bottom plug was not connected. So....I connected the plug thinking that the fuel in the water was from unburnt fuel from that cylinder. I ran it the rest of the year like that. Still seemed low on RPM's still not as much power and still not idling very well still fuel in the water, but it was manageable.
This fall, I decided to rebuild the carburetor to hopefully clear these issues up (I am not a mechanic and have never done anything like this before) After watching videos and reading forums I felt I had a pretty good grasp and it was also recommended that I rebuild the water pump as well. So I rebuilt the carburetor, with the kit from this site. I did notice that the slow speed needle was out way further than it should be like 5 or 6 turns. Knowing what I know now. . there is a good chance that was the major cause of all my problems. When I put everything back on I also noticed that the butterfly valve for the throttle was not opening all the way at WOT. So, I lined up the cam follower with the end of the biggest lobe (which should be WOT) and adjusted the linkage so the valve was completely horizontal. I do have a service manual, so I followed it to link and sync the throttle with the 2 lines. I also replaced the impeller on the lower gear unit and put in all new fuel lines.
I got it started, but it was running even more rich than before I couldn't even keep it running. There was a lot of fuel in the barrel that I was running it in. It was recommended that I take a look at the fuel pump, so I just went ahead and put in a new one. Things improved with the fuel pump and I was able to start it and keep it running. I was able to make adjustments with the slow speed needle and could hear changes in the engine. I could put it in gear and increase the throttle but it would seem to sputter. I checked the spark, but it was with a cheap tester that just shows a light if there is spark or not. When I checked it I noticed some spark coming from behind the bottom coil, almost like it was sparking to the engine block.
Oh yeah. I have a 1973 18HP that has a lot of compatible parts as well. .. so, I took the a coil from that to fix the spark problem.
So, where I am at now. . I can get it to start pretty easy and it will run, but I am still seeing a lot of fuel in the water and the plugs are still wet and black. I did notice a small pool of fuel at the front of the carburetor (not sure if that is normal) and also when I put the carburetor back in from the rebuild it looks like I might have pinched the vacuum line the is back there. (I'm not sure what that does....fuel pump?) My next step in my head is to change the points and condensers with the thought that I don't have enough spark and unburnt fuel is coming out of the exhaust and showing up in the water. I am hesitant to take off the flywheel because I really don't want to mess with the timing. I was also thinking that the reed valves may be at fault and the 18 HP motor has the same part number. So maybe between the 2 motors I can get one good one! Another thing to note, I have been able to start it without using the choke and that leads me to believe that is still pretty rich.
Also, the idle screw is missing, so I could be going to far and allowing the RPM's to go too low, maybe that is the cause of my idling woe's. I have an RPM indicator on the way and I plan to get that part figured out then I can make other adjustments.
It really didn't run that terrible before I started tinkering and I am afraid I am making it worse, but I don't think I have ruined anything yet?? Am I on the right track here?