HTHM Posted July 5, 2008 Report Share Posted July 5, 2008 Well, I put the 20 hp on Lure Laundry, and on GPS I am doing 20 MPH at wide open throttle. Not too bad I think! However............when I try to go 1/2 throttle the motor will not run very smoothly, and when I try to troll it stalls out all the time. Any ideas as to why this is? This was done with me on the tiller, and my 175 pound son in the front. The rate of speed was the same when positions were reversed. The motor is a 81 (?) Johnson seahorse. Link to comment Share on other sites More sharing options...
modny Posted July 5, 2008 Report Share Posted July 5, 2008 that seems slow to me , even at WOT my old merc 20 could push me, my dad and my 17 foot sylvan at close to 30 mph has the motor had a carb clean? or adjustment? might have to do with the floats. could be running rich and chokin out maybe. Link to comment Share on other sites More sharing options...
HTHM Posted July 5, 2008 Author Report Share Posted July 5, 2008 It was just bought from Bay city marine, and they indicated that the motor was fully serviced and tuned up. My boat is a 14' fiberglass. Link to comment Share on other sites More sharing options...
nancur373 Posted July 5, 2008 Report Share Posted July 5, 2008 have the carb and jets cleaned. If problem still persists try taking a compression reading. Link to comment Share on other sites More sharing options...
modny Posted July 5, 2008 Report Share Posted July 5, 2008 bay city on hester is a pretty solid place/ i'd call them up and see what they say...especially if u just bought it Link to comment Share on other sites More sharing options...
HTHM Posted July 5, 2008 Author Report Share Posted July 5, 2008 bay city on hester is a pretty solid place/ i'd call them up and see what they say...especially if u just bought it I agree, it took me a year before I finally pulled the trigger on a deal there, and Clarence seems like a decent fellow. I asked him prior to the purchase if the motor had been serviced, listened to it run, and felt confident walking out the door. I will talk to him on Monday. Link to comment Share on other sites More sharing options...
Greencoachdog Posted July 5, 2008 Report Share Posted July 5, 2008 Pull the spark plugs and see what they look like. What gas/oil mix ratio were you using? Was it fresh? How old is you fuel line? Link to comment Share on other sites More sharing options...
BillM Posted July 5, 2008 Report Share Posted July 5, 2008 If you just bought it, take it back. Make the dealer worry about it. Link to comment Share on other sites More sharing options...
nancur373 Posted July 5, 2008 Report Share Posted July 5, 2008 Also the choke may be sticking a little. Link to comment Share on other sites More sharing options...
glen Posted July 6, 2008 Report Share Posted July 6, 2008 20mph top speed is about right for that (boat 400lbs or so) plus people. I aint sure what is wrong with it. But if the fuel line is old and the rubber is hard i would buy a new one. Link to comment Share on other sites More sharing options...
forrest Posted July 6, 2008 Report Share Posted July 6, 2008 Obvious issues with a new purchase? Call the dealer. 20MPH.....nothing wrong with 20MPH as long as 20MPH is normal for that boat, engine, prop set up. Ask the dealer about that too. forrest Link to comment Share on other sites More sharing options...
blehst Posted July 6, 2008 Report Share Posted July 6, 2008 (edited) my dad has a 14.5 foot boat. with a 30 and he only does 32mph. so id say your right around ball park Edited July 6, 2008 by blehst Link to comment Share on other sites More sharing options...
Zamboni Posted July 6, 2008 Report Share Posted July 6, 2008 that seems slow to me , even at WOT my old merc 20 could push me, my dad and my 17 foot sylvan at close to 30 mph His reading was by gps-guessing your reading was the boats dreemometer? Link to comment Share on other sites More sharing options...
modny Posted July 6, 2008 Report Share Posted July 6, 2008 His reading was by gps-guessing your reading was the boats dreemometer? i'm not even lying about this at all. mind you it was like 16 years ago when i weighed 150 lbs less, and my old man atleast 50 hahah Link to comment Share on other sites More sharing options...
sturgman Posted July 6, 2008 Report Share Posted July 6, 2008 Just a thought... I am experiencing the same problems as you with my 9.9 after installing a new propeller.. Maybe your prop pitch is incorrect as I have discovered mine is.. Link to comment Share on other sites More sharing options...
FinS Posted July 6, 2008 Report Share Posted July 6, 2008 that seems slow to me , even at WOT my old merc 20 could push me, my dad and my 17 foot sylvan at close to 30 mph has the motor had a carb clean? or adjustment? might have to do with the floats. could be running rich and chokin out maybe. id like to see that on video Link to comment Share on other sites More sharing options...
HTHM Posted July 6, 2008 Author Report Share Posted July 6, 2008 Pull the spark plugs and see what they look like. What gas/oil mix ratio were you using? Was it fresh? How old is you fuel line? Plugs are brand new, (dealer has indicated that the motor was just tuned up, with new points and condenser and he says the coil is good) Gas is 50 - 1 approximately 2 months old with stabilizer in it. My fuel line is max one year old, looks brand new. Link to comment Share on other sites More sharing options...
HTHM Posted July 6, 2008 Author Report Share Posted July 6, 2008 Just a thought... I am experiencing the same problems as you with my 9.9 after installing a new propeller.. Maybe your prop pitch is incorrect as I have discovered mine is.. original prop as I understand it Link to comment Share on other sites More sharing options...
Fish4Eyes Posted July 6, 2008 Report Share Posted July 6, 2008 My 40hp evinrude does not like to troll either, but when on the throttle it goes smooth. Link to comment Share on other sites More sharing options...
Randy Posted July 6, 2008 Report Share Posted July 6, 2008 ....... when I try to troll it stalls out all the time....... I agree with other posters, this would lead me to believe that the carburetor would need cleaning. Since you just bought it, take it back to the dealer and get him to fix it. Link to comment Share on other sites More sharing options...
Zamboni Posted July 6, 2008 Report Share Posted July 6, 2008 i'm not even lying about this at all. mind you it was like 16 years ago when i weighed 150 lbs less, and my old man atleast 50 hahah Didn't mean to offend-boats speedometers were generally innacurate and most people are suprised at their actual speed when a gps is used. Those GPS units must be very heavy as they cause many boats to go 5-10mph slower Link to comment Share on other sites More sharing options...
HTHM Posted July 6, 2008 Author Report Share Posted July 6, 2008 Well, I just looked over the motor, and yes the plugs are new, the fuel lines appear to be sound, however I am missing the lean rich adjustment knob at the center of the motor. Could it be that the motor is running too rich or too lean?? Link to comment Share on other sites More sharing options...
forrest Posted July 6, 2008 Report Share Posted July 6, 2008 Well, I just looked over the motor, and yes the plugs are new, the fuel lines appear to be sound, however I am missing the lean rich adjustment knob at the center of the motor. Could it be that the motor is running too rich or too lean?? Anything is possible, fuel systems are tricky.....a service manual is your motors second best friend. There is almost nothing worse than a man made problem, if its free, before anything gets messed up worse ask the dealer. forrest Link to comment Share on other sites More sharing options...
modny Posted July 6, 2008 Report Share Posted July 6, 2008 Didn't mean to offend-boats speedometers were generally innacurate and most people are suprised at their actual speed when a gps is used. Those GPS units must be very heavy as they cause many boats to go 5-10mph slower well im just going by another boats speedo so it def could have been inaccurate Link to comment Share on other sites More sharing options...
bigbuck Posted July 7, 2008 Report Share Posted July 7, 2008 I'd give them a call and let them know that they owe you a lean adjustment knob, you may be running either too rich or too lean and that's why she doesn't like trolling or part throttle. Link to comment Share on other sites More sharing options...
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