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76' 17 Montauk w/ 2005 Johnson Issues

tunahunter197

New member
Hey guys...so I bought the boat from my uncle and had it shipped out a month or so ago. I'm having nothing but troubles with the motor. The motor is a 2005 Johnson 115hp (J115PLSOR), 2 stroke carbed with 300hrs. I feel the issue is fuel related but a little lost at this point.

I've ran the boat a handful of times and my main issue is at idle the engine wants to stall out and sounds like it is starving of fuel. At first I was able to give it more throttle and it stumbled/sneezed but got up to speed (boy that little boat is fast at WOT!) but my main issue is at low rpms. Since I've replaced a bunch of parts the boat is a dog and bogs down while giving it throttle and not able to get up to speed.

Since receiving the boat I've changed:
- Fuel primer ball
- Fuel line
- Rebuilt carbs
- New motor fuel filter
- New tank & connections (new fuel as well)
- New fuel/O2 seperator and clear draining bowl
- Check plugs, look good (will be changing)
- Checked spark on all 4 cylinders, check
- Compression check after work today, but have suction through each throttle body (will update the thread with compression #'s)

Some notes for thought:
- On initial startup I use the choke but after stalling the motor I constantly have to use the choke to kick the motor over
- No fuel leaks present
- The new primer ball is not rock solid but also not flat by any means (seems normal to me)
- The boat has the original Morse controls ('76)
- Neutral RPM's are ranging from 800-1000 but drop to 600-700 shortly after start up
- My uncle had the same problems with the old motor but not totally basing my due diligence off this since he didn't really maintain this engine well
- Ran motor on a portable tank, same symptoms so ruled out everything before the motor (if fuel related)
- When putting the Morse control into the fwd clutch position I don't see any movement to the linkage but moving the throttle a little further there is movement
- When I take off the air silencer small puddles of fuel are present, normal?

Final thoughts:
- Could it be a failed powerpack?
- Could it be a failed fuel pump? May have ruled this out since we lifted the portable tank above the motor (gravity feed) to take stress off the fuel pump, same symptoms.
- Could it be the original Morse controls?
- Since my RPM's are pretty spot on I don't think an adjustment is needed, but I'm not a professional.

Thanks!
Rob
 
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