YAMAHA 50HP 4 STROKE INTERMITENT ROUGH RUNNINGP

GORD B

Recruit
Joined
Jul 10, 2003
Messages
2
MOTOR WILL SEEM TO RUN FINE FOR HOURS AND THEN RUNS LIKE A BAG.FIRST HAPPENED THROTTLING DOWN<br />FROM 5000 RPM TO IDLE .IDLED LUMPY,THROTTLED UP<br />5000RMP THEN IDLED FINE @ RAMP.SECOND TIME RAN<br />FINE 6HRS THEN BAGGED @ 5000RMP (DROPPED 1000RMP)<br />SEEMED IT LOST A LITLE ON ALL 4 CYL NOT JUST ONE.<br />CHECKED <br />FUEL TANK VENT O.K.(OPENED CAP STILL DID IT)<br />REPLACERD PLUGS O.K.<br />HIGH TENSION LEADS FOR ARC O.K.<br />WATER IN FUEL O.K.(RAYCORE)<br />NOW CONVINCED IT WAS IGNITION IT WENT TO THE LOCAL<br />WRENCH.THEY HAD THE SAME MOTOR IN SHOP SO WE SWAPPED CDI,TRIGGER COILS,CHARGE COIL,RAN OFF REMOTE TANK SAME THING.STUMPED HIM SO I HAVE IT BACK.<br />WHILE RUNNING ON MUFFS IN DRIVEWAY TRYING TO TROUBLE SHOOT I NOTICED FUEL FILTER BOWL RUN TO 1/2 EMPTY THEN FILL TO 3/4 THEN FILL COMPLETLY.<br />(I FORGOT TO MENTION THIS WAS WITH THE DONOR MOTOR FUEL PUMP)THIS HAPPENED WHILE RUNNING OFF A <br />REMOTE TANK CONNECTED TO THE IN SIDE OF THE FUEL<br />FILTER.I HAVENT BEEN ABLE TO DUPLICATE THIS IN THE DRIVEWAY YET BUT I THINK IT MAY BE A CLUE.<br />QUESTION.WHAT COULD CAUSE FILTER BOWL LEVEL TO RISE AND FALL IF FUELPUMP HAS BEEN ELIMINATED<br />AS PROB. AND A REMOTE TANK IS HOOKED TO IN PORT<br />ON FILTER BOWL?
 

jim dozier

Lieutenant Commander
Joined
Jan 8, 2003
Messages
1,970
Re: YAMAHA 50HP 4 STROKE INTERMITENT ROUGH RUNNINGP

Leaking hose connector on the engine to fuel line fitting.
 

GORD B

Recruit
Joined
Jul 10, 2003
Messages
2
Re: YAMAHA 50HP 4 STROKE INTERMITENT ROUGH RUNNINGP

THANKS FOR THE RESPONSE JIMD.<br />IS IT POSSIBLE LINE HAS A PIN HOLE AND DRAW AIR BUT NOT LEAK FUEL.IVE ALLREADY CONSIDERED THERE MAY BE AIR LEAK AT CONNECTIONS AND HAVE REPLACED STOCK HOSE CLAMPS WITH GEAR CLAMPS BUT I'LL EXAMINE CLOSELY FOR PIN HOLES
 
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