Yamaha 2004 50 2 storke

[Mangoman]

Hey guys,

Need some help. Rebuilt the carbs and running much better, but still will not take the power after sitting idle for a while. When running tilt up into shallow water at idle, then shutting her down for a drift, crank her up and advance the throttle and won't budge past medium range for a while until she is ready.
Once the motor has run at half throttle for a while, gradually the rpm increases and off we go. Fuel pump? I'm thinking maybe hole in fuel pump diaphram, full runs great. Any help would be much appreciated.

 

[Yamajoe]

Re: Yamaha 2004 50 2 storke

Could be fuel pump;try squeezing the primer when you takeoff, what happens? Does the primer feel firm, spongy or deflated? If when priming fuel,motor picks up, pump needs an overhaul; if the primer bulb is spongy check for restrictions and airleaks from the tank to motor. Is the inline fuel filter clean? I suspect an air leak in the fuel system, check from tank connectors, lines through to fuel pump.
What are the state of the plugs? Check that you have good spark on all plugs;
Recheck the link and sinc and timing.

 

[Mangoman]

Re: Yamaha 2004 50 2 storke

Yamajoe thanks for the input,

Primer bulb is firm, new plugs, and new fuel filter. Air leaks and timing I am yet to get into, so thats where I'll go this week. Seems like the timing on these outboards is pretty straight forward. Could it be possible to have a prop with to much pitch, causing it to load up because it does run great in the driveway.

Thanks Again. Pulling my hair out.

Mango

 

[Silvertip]

Re: Yamaha 2004 50 2 storke

An engine running on half its cylinders will seem to run fine in the driveway on muffs with no load. If the engine runs great at full throttle then the fuel pump, lines, and primer bulb are not the issue. You still have a carb problem on one or more carbs. When you rebuilt the carbs did you fully disassemble them, soak them in the carb cleaner, ensure all passages are clear, blow them out with compressed air and reassemble with new kits? Is float level set correctly? Is link&sync correct?

 

[Mangoman]

Re: Yamaha 2004 50 2 storke

Supreme,

Thanks for the input, did all that with the carbs during overhaul, but the manual I have really did't get into the sync of the three carbs. Float level measured per manual in the seated position was correct. Because the primer bulb is firm and is running good flat out, still makes me want to lean toward the carbs again. Checking timing and plug wires today. Whats strange is after I get her runnig flat out, I can chop the throttle and immediately go full again with no problem. The hesitation only occurs after idling.

Thanks again for all responses,


Mango

 

[Silvertip]

Re: Yamaha 2004 50 2 storke

Is the idle mixture adjustable on those carbs? If so, you may have them set too rich so it's loading up at idle.

 

[Mangoman]

Re: Yamaha 2004 50 2 storke

Hey,

I think I have found the problem, thanks to all of your responses generating some more thinking. I ran the engine with the muffs this morning and noticed the #2 cylinder was warm, but not as warm as the others. Started doing some continuity checks on the ignition coils and found what I believe is a bad primary coil. From what I understand there are 2 circuits in the ignition coil, the primary and the secondary. The one that goes from the plug connection to ground (primary?) had no continuity. The others showed about 3,000 ohms. I have the part coming hopefully tommorrow, and I will keep you updated. Also did a spark test and the #2 was real weak, so I think I'm on the right track, I hope anyway. Thanks again for the input.

There is no mixture on these carbs, just the jets and idle adjustment.

Later,
Mango

 

[Mangoman]

Re: Yamaha 2004 50 2 storke

I now have a much better spark on #2, but that was not the problem. Went back to the carbs, and this time I soaked them for a couple of days and was surprised to see all the crap that came out. Boats running great now. So before you go chasing ghosts like I did, clean the carbs real good, especially with this gas problem were having now. Thanks again for all the responses.

Mango