Hey y'all, I'm a new member here! I'm new to outboards but not to doing my own work. I don't like owning things which I have no knowledge of, so to that end I'll be ordering a SELOC repair manual and/or a factory repair manual for my outboard. I'll be more than happy to help others out on here as I learn!
Anyhow, a few weeks ago I bought a 14' aluminum v-hull jon boat. It has a 1974 Johnson 50HP, model 50ESL74M, that's giving me some trouble and generally runs like crap. I'm trying to get it in good running order but right now it barely even idles long enough for me to push the fast idle lever down and get it in gear!
Here's the symptoms:
- Won't idle in neutral or in gear.
- Has more power at 90% throttle than it does at 100%.
- Hard to start (requires brief choking if it sits for more than a minute or two even after just having been run, also have
to crank it quite a bit)
- Sometimes, depending on throttle setting, seems to miss in one cylinder (engine is a twin cylinder).
- Doesn't seem able to rev to it's full speed, it will only push my boat to around 17 MPH.
And here's the story:
When I first bought the boat/motor, the guy selling it (private seller) said it would only run about 15 MPH and needed the carbs cleaned. I registered the boat and trailer and went down to the river to see what I was working with. First off, water pump is working and the engine stays cool enough I can leave my finger on the upper water jacket all day long. Took her out in the channel after having to crank it for several seconds, and she would barely stay running at idle as well. Around 1/4 throttle or so it seemed to clear up and run smooth, boat was doing around 5 MPH at this point. I opened it up to full throttle and the chartplotter showed a speed of 17 MPH which is about what the previous owner said to expect, and the engine seemed to surge as well.
Took it back to the house and, remembering what the seller told me about the carbs needing cleaned, I picked up two Johnson/Evinrude kits and pulled the carbs apart. Found brand new parts in both of them! Since I already bought the parts, I stripped each one down and blew all the passages out with air, removed the one jet that I found at the bottom of each bowl and made sure that was clear, and reassembled them both with new floats, float valves/seats, welch plugs, gaskets, etc. I also took the filter screen off the fuel pump and only found some minor debris in there, which I blew out with air as well. I set the idle mix screws back where I found them (1.5 turns out/open) and headed for the river again the next day.
Back on the river it behaved the same way as before, except now instead of surging at full throttle, it would just lose
power. Backing off to 90% throttle seemed to clear it up a bit but still only topped out at 17 MPH. Squeezing the primer bulb while running at various throttle settings didn't seem to affect the engine in any way.
I'm thinking because of the way it behaves at full throttle that I might have a fuel delivery issue, and since the carbs are clean, perhaps I need to take a look at the fuel pump and lines. Am I on the right track with this thought? What's the best way to test this, or is there something else I need to look at? I don't think it's ignition-related, although I read about outboard ignition systems and haven't ever worked on or diagnosed one before.
Anyhow, a few weeks ago I bought a 14' aluminum v-hull jon boat. It has a 1974 Johnson 50HP, model 50ESL74M, that's giving me some trouble and generally runs like crap. I'm trying to get it in good running order but right now it barely even idles long enough for me to push the fast idle lever down and get it in gear!
Here's the symptoms:
- Won't idle in neutral or in gear.
- Has more power at 90% throttle than it does at 100%.
- Hard to start (requires brief choking if it sits for more than a minute or two even after just having been run, also have
to crank it quite a bit)
- Sometimes, depending on throttle setting, seems to miss in one cylinder (engine is a twin cylinder).
- Doesn't seem able to rev to it's full speed, it will only push my boat to around 17 MPH.
And here's the story:
When I first bought the boat/motor, the guy selling it (private seller) said it would only run about 15 MPH and needed the carbs cleaned. I registered the boat and trailer and went down to the river to see what I was working with. First off, water pump is working and the engine stays cool enough I can leave my finger on the upper water jacket all day long. Took her out in the channel after having to crank it for several seconds, and she would barely stay running at idle as well. Around 1/4 throttle or so it seemed to clear up and run smooth, boat was doing around 5 MPH at this point. I opened it up to full throttle and the chartplotter showed a speed of 17 MPH which is about what the previous owner said to expect, and the engine seemed to surge as well.
Took it back to the house and, remembering what the seller told me about the carbs needing cleaned, I picked up two Johnson/Evinrude kits and pulled the carbs apart. Found brand new parts in both of them! Since I already bought the parts, I stripped each one down and blew all the passages out with air, removed the one jet that I found at the bottom of each bowl and made sure that was clear, and reassembled them both with new floats, float valves/seats, welch plugs, gaskets, etc. I also took the filter screen off the fuel pump and only found some minor debris in there, which I blew out with air as well. I set the idle mix screws back where I found them (1.5 turns out/open) and headed for the river again the next day.
Back on the river it behaved the same way as before, except now instead of surging at full throttle, it would just lose
power. Backing off to 90% throttle seemed to clear it up a bit but still only topped out at 17 MPH. Squeezing the primer bulb while running at various throttle settings didn't seem to affect the engine in any way.
I'm thinking because of the way it behaves at full throttle that I might have a fuel delivery issue, and since the carbs are clean, perhaps I need to take a look at the fuel pump and lines. Am I on the right track with this thought? What's the best way to test this, or is there something else I need to look at? I don't think it's ignition-related, although I read about outboard ignition systems and haven't ever worked on or diagnosed one before.