Help with Yamaha 2004 50TLRC 2 stroke problem

[Steve Helmrich]

I have a 2004 yamaha with an intermittant problem....I have invested nearly $2000(including extensive analysis by Yamaha certified mechanics) and they are baffled....

After the engine warms up...you can not exceed 5 mph without the engine konking out...here's what we have done...new plugs, new fuel filter / water filter..( there is no water or contaminant in the gas) rebulit the 3 carbs and (cleaned multiple times including run though an ultra sound cleaner), new thermastate, new fuel pump, ...most recently changed out the pulsar coil ...and then finally the CDI...after the cahnged pulsar coil we thought we nailed it but, after 3 days the intermmitant problem is recurring....I think it is electrical ...when the engine runs it runs well...idles well, you can take it out of gear and rev up to 4000/5000 RPM...but, when the intermmitant issue is occuring (once the engine warms) once you put it in gear and attmept to go more than about 5 mph it konks out...starts righ tup again ...no hesitation....then repeats the same thing...up to 10 or 15 try's and then magically ...will take off....can not help but think this is an electrical issue...because the engine runs and sound great ( when it runs)....one trick ( and I know this is not good and used for emergecny only ) but, when it starts acting up...if I take it out of gear, throttle up then quickly pop it into gear ...it overcomes the issue and takes off.... any body know what is going on.....it does not appear to be the low oil safety...(e.g. if you run low on oil the engine will limit it's speed to 5 mph....that is fucntioning ok....)

And when this issue starts occuring ...the eneigne will immediatley fire back up...but, once in gear can not exceed 5 mph).....we are baffled...not to mention it is getting expensive...even Yamaha after repeated other tests...is baffled...any ideas?????? HELP

[boats.net]

Needs to be tested when the problem is occurring, check charge coil, pulsor coil and CDI output voltage at time is shuts off. If pulsor made some improvement check all wire connections on ignition components and all ground wires to engine block. Can be run on a new main harness and key switch to eliminate electrical problems in boat.

[Steve Helmrich]

Ok thank you for the response....they have run a variety of voltage output checks which is why they changed out the pulser coil...but that did not resolve the issue, the CDI appeared to ...but now the issue is recurring...being sporadic doesn't help ...

Could it possible be the voltage regulator...if that were acting up...could that be the sporadic issue that is occuring>?????

[robert graham]

Maybe check some of the simpler, more obvious things like fuel tank pick-up, check valves, primer bulb/check valves, quick-disconnect on cowl, air leaks in fuel system, carb float needle valves. Problem sounds like it could be electrical or fuel related. Good Luck!

[Steve Helmrich]

Thanks Robert for yoru response...I'll take any and all thoughts and ideas...I almost don't know what to do next....the thing that really baffles me is why (if out of gear) it will rev up fine and if I drop it into gear once it's reved up...it resovles the immediate problem and takes off....that is what I don't get....and the fact that when the problem is occuring and the engine konks out...it will immediately start back up....jsut can't throttle any were past 5 mph

[robert graham]

Is your fuel tank vented properly? No air leaks in fuel delivery system? Have you tried pumping the primer bulb when problem occurs, which could indicate a fuel pump issue? Good Luck!

[Steve Helmrich]

Thanks again Robert...no I have never tried pumping the ball when it acts up...but, I will.....next time....I did put a new fuel pump on ...

Actually I have a 2004 CapeCraft boat that has on and off had a little venting issue....occassionally gas does get in the vent tube which makes it hard to fill with gas .... I think I have dealt with that and blown all the gas out of the line....I have do not seem to have difficulty filling up any more...but, used to because it was not venting properly....

Thank again for your responses...I will be checking all these things....

[dorf]

Just a wild wild guess, how about the anti-siphon valve in the on board fuel tank outlet fitting ???

If it aint opening..... no fuel flow.

Tell us of the fix when you find it.

[markle]

markle

Hey Steve,try this.Start the motor and disconnect 10 pin harness back at the engine connector.That will eliminate the shifter assy and everything external from motor.Run it like that and see how it go's.Yall' just have to plug it back together to turn it off.Let us know one way or nother.

[Steve Helmrich]

Thanks Dorf/Thanks Markle...I'll check those things..I really like your suggestions and ...they're cheap fixes if they work...anybody with any other thoughts please let me know.....and, I will post the solution if I can ever find one....thanks you guys...

Steve

[mrpontoon]

tank

try a 3gal.tank with a hose to see if it is yout tank or hose

[robert graham]

Thanks and we'll all be very interested to hear what this turns out to be. Hopefully something simple, obvious and cheap! Good Luck!

[ronniepearson]

yamaha 50TLRC

Ok I have this same engine. I had a problem like this. My motor would start up an idle perfect. Soon as I went to put it in gear and take off it would die. I changed bulbs, plugs, gas hoses, ****pits. You name it and I tried it. I cleaned the carbs a few times. The carb was my problem though. After tearing the carbs apart I used some small wires to run it through the orffices. When I did that, thats when I realized that the holes I thought werent plugged were almost completely plugged. You couldnt tell unless you ran something through those small holes in the carbs. By the way I took mine to a dealership and they couldnt fix it either. Hope this works.