1995 Yamaha 55hp 2 cylinder C55TLRS

[Carmstrong]

Having some problems with my outboard
first it was idling crappy and running bad over all
I removed the carbs and thuroughly cleaned them
the bottom carb had a bunch of blackish looking sediment in it
almost looked like something had broken down in the fuel system and then ended up in the bottom carb's float bowl
also took apart the fuel pump, cleaned and checked it out too
it looked fine
So thinking I had the problem resolved I took it to the lake for a water test
after some adjusting I got it idling nice runs good at low end and mid range
however it's still experancing a power loss at top end
then after attempting to run it for a while it will foul the bottom cylinder spark plug
so I'm back at it look for something more:
I've just eliminated a second inline feul filter, plus the fuel line from the tank looked to be to long, shortened that,
then I started testing for fuel flow from the tank to the carbs
it seemed to be a bit restricted so I removed the anti-siphone valve
now the fuel flow seems to be very well

another thing I noticed is the linkage for the timing appears to have some slop & or play in it when it's sitting at idle so I'm wondering if it might have some timing issues
plus it looks like some smuck was wreching/ vise gripping on the adjustment screw & nut
any others out there had experiance with this model?
and with the linkage or timing/ timer coil system?
wonder what's the best way to get the play out

By the way I bought this boat used
looks like it's my time to discover how it's been treated by previous owners & or repairs shops

Thanks
P S I checked the other forums for power loss issues one was suggesting thermostat issue could be a culprit, so next lake test I'll pull it out too and block the hole

 

[rodbolt]

Re: 1995 Yamaha 55hp 2 cylinder C55TLRS

check the timer base for wear, if the bushing wears the pulser coils hit the magnets.
timing can become eratic and the engine runs poorly. the slop at the advance arm is normal, its how it as designed.
its also why the bushing wears.
last I looked only 1 timer base is left and it has a bad trigger coil.
its 1 of 2 japan had. both had bad trigger coils.
dont ask how I know.

 

[Carmstrong]

Re: 1995 Yamaha 55hp 2 cylinder C55TLRS

Thanks much for the tips and more specifics
greatly apperiate it

 

[Skyking711]

Re: 1995 Yamaha 55hp 2 cylinder C55TLRS

Hi,
I too am having similar problems w/ my 55. Were you able to get the carbs off w/o having to take off the lower cowling?

If so, any suggestions?

Thanks in advance.

 

[Skyking711]

Re: 1995 Yamaha 55hp 2 cylinder C55TLRS

Hi,
I too am having similar problems w/ my 55. Were you able to get the carbs off w/o having to take off the lower cowling?

If so, any suggestions?

Thanks in advance.

 

[robert graham]

Re: 1995 Yamaha 55hp 2 cylinder C55TLRS

Maybe a bad fuel pump diaphragm causing fuel to get pulled into that bottom cylinder and fuel fouling that spark plug? When you pull that spark plug is it wet with gas? Remove fuel pump from motor but leave the fuel lines attached, squeeze primer bulb and look for gas coming out from back of pump. Good Luck and let us know what you find!