1992 115hp Johnson - low power, low rpm

[Yukonovitch]

Hi all thanks for a great forum.<br /><br />Just bought a boat with '92 115hp Johnson. Original owner says within the last week he had it running up around 4400 rpm and approx 25 mph. <br /><br />First run out I couldn't get over 3400 rpm and never past 15mph, and no amount of trim allowed me to get on step. The motor put out a lot of smoke as well. Supposedly the outboard shop here did some work on the choke recently, and I'm thinking these symptoms are related to that. When I push in the key to choke, I hear one click from the motor.<br /><br />I guess my question is, since I'm really quite new to outboard motors, does this sound like choke problems? Any other possible causes that I'm not thinking of would be greatly appreciated. <br /><br />Thanks in advance

 

[JB]

Re: 1992 115hp Johnson - low power, low rpm

Ahoy, Yukonovich. Your engine is almost certainly running too rich, and stuck chokes are a good suspect. Other possibilities are stuck or misadjusted floats.<br /><br />When you get her runnning right, you should be able to get between 5000 and 5500 at WOT. If, as the previous owner told you, 4400 is rpm at top speed you may be seriously overpropped. Very bad for your engine. Check it out.<br /><br />Red sky at night. . . <br />JB

 

[Yukonovitch]

Re: 1992 115hp Johnson - low power, low rpm

Thanks J.B.!!<br /><br />I just ran out and checked out the prop. It says 13 3/4 x 15. Not sure yet on what those numbers mean, I'm assuming diameter and pitch?? <br /><br />As far as 4400 rpm being at WOT, he didn't specify that, he just mentioned that that was an easily attainable rpm.<br /><br />So here's hoping it's something fairly easy like the choke, and I can stand down from Panic mode

<br /><br />Thanks alot J.B., from reading this board you seem to be a GREAT help to alot of folks.

 

[Yukonovitch]

Re: 1992 115hp Johnson - low power, low rpm

*Update*<br /><br />The smoking has mostly disappeared (bad gas?)<br /><br />I have been able to coax the boat up on step but ONLY after approx 5 mins of very slow throttle control movement. It usually tops out at 3400 rpm...15mph, then seems to stay there for a couple mins. Then seemingly of it's own accord, the motor begins to slowly rev up to about 4200 rpm and 27 mph. <br /><br />Any ideas why it's taking so long to get up to speed, and why the big pause at 3400 rpm?<br /><br />115hp Johnson 1992 pushing a 21' runabout