mERCURY 2002 9.9 4 STROKE NO FULL THROTTLE

[jlyar]

I HAVE A 2002 MERCURY 4 STROKE 9.9 WITH 10 HOURS ON A 4000 POUND SAILBOAT THAT<br />doesn't seem to reach full WOT. The motor has been modified to have a remote throttle and <br />shift using a Mercury supplied kit. The motor starts and runs very well up to three quarters <br />throttle. If the throttle is advanced from three quarters to full throttle range on the motor <br />I can see the throttle linkage actually move to the full throttle position on the<br />motor but see or feel or hear nothing happen to indicate I have advanced the throttle .<br />The motor is a sailpower bigfoot 25" electric start with a 3 blade 10x9 prop.<br /><br />Any ideas would be appreciated.<br /><br />John

 

[Reel Appeal]

Re: mERCURY 2002 9.9 4 STROKE NO FULL THROTTLE

jlyar,<br /> If your Mercury is carburator eguipped,there may be a throttle stop screw on the carb linkage.Once you locate the correct screw try backing it out(counter-clockwise) a few turns(at a time)until you get it right.Please be careful not to over-rev the motor while adjusting/checking.Also,check to make sure the linkage rod to flywheel/stator is not disconnected.If it is the ignition timing may not be advancing.

 

[12Footer]

Re: mERCURY 2002 9.9 4 STROKE NO FULL THROTTLE

Welcome to iboats.com.You're gonna love this place <br />But Reel Appeal has the best advice.<br />If you are sure that the throttle plate on the carb is opening all the way, you may have a slipping hub in the prop. Has it allways done this? If so, it may be setup (trim or over-propped) to begin with.<br />That's a lot of hull for a small engine, and if it doesn't have a prop designed for lower speed, high torque, it will die and early death. It needs full RPM, or at least, the ability to reach full RPM for a long life.<br />If the engine is proppped for a 12ft jon boat, it will act like that on your sailboat hull.

 

[jlyar]

Re: mERCURY 2002 9.9 4 STROKE NO FULL THROTTLE

ALL,<br /><br />Thanks for the information on my problem. The motor runs great up to and at three quarter throttle. It has done this since it was new. I had a 9.9 johnson 2 stroke on this same boat that performed without any problem until someone took it. The carb linkage looks ok, the linkage seems to be moving the throttle wide open to the stop ok. If I watch the linkage at the carb<br />it sure seems to move everthing as far as it should and like I say after it reaches about three quarters throttle the linkage keeps moving but I feel or hear nothing more from the motor.<br />There is no misfire, no stumble, no cut out, just no more power.<br />Do you think it could be fuel problem.....bad fuel hose,bulb??????????<br /><br />Thanks again.<br /><br />John

 

[Reel Appeal]

Re: mERCURY 2002 9.9 4 STROKE NO FULL THROTTLE

jlyar,<br /> If the carb. butterflys(flaps) are horizontal(or flat) when at 3/4 throttle,then the motor IS at full(throttle) rpm's and your linkage may need adjusting.Otherwise,the prop is either over-pitched or under-pitched.Over pitched would cause engine load,lower rpms,cavitation(bubbling) or ventilation(check prop).Under pitched would cause higher rpm's.Full speed potential would not be met.Does it sound like it's reaching full rpm's? Advice: Look up the prop size on your old motor(if year is known)and compare.

 

[jlyar]

Re: mERCURY 2002 9.9 4 STROKE NO FULL THROTTLE

The butterfly is not full open at 3/4 throttle. As I said above, everything seems to be ok with the linkage both at my throttle lever and at the carb on the motor. There just is not anything happing from 3/4 to full throttle and I think I should hear, feel something from the motor. I think it is dealer time for my concern as this motor has never been set up by a dealer, I bought it new through the net and had it shipped to me, so it is one of the in-the-box motors that has never seen a dealer. I don't seem to be able to get any information on a different prop for this motor from Mercury etiher. I am not expecting any great speed as my hull speed is around 5 knts. anyway. Just would like to know if the Motor is OK.<br /><br />Thanks for your input and information.<br /><br />John