91 48spl wont reach high rpm's in forward

[bowhunter83]

I have a 91 48spl on a 21' pontoon. It runs fine,but will not reach high rpm's or top speed in forward. In reverse and with the choke lever up the rpm's will rev up,but in forward they will not and it feels like it goes faster in reverse than forward. Ive checked the manual and adjusted the throttle linkage and all that mess to spec. but even with the throttle lever in full forward,the butterfly valves on the carbs are wide open, but it will not rev up or reach top speed. Not sure what size the prop is off hand,but Ive had the boat for 3yrs now and the prop hasnt been changed and it ran fine last year and at the begining of summer,and just started doing this the last few weeks. The spark plugs were changed 2 months ago with the same size as the ones that were removed. And its got me stumped,bc I dont think its a fuel prob being as it revs up in reverse. And shouldnt be a timing issue since it goes fine in reverse. Any help or ideas would be appreciated.

 

[bowhunter83]

Re: 91 48spl wont reach high rpm's in forward

ttt

 

[steelespike]

Re: 91 48spl wont reach high rpm's in forward

Are you sure its running on both cylinders.Dissconect and ground one plug wire at a time see if it runs.

 

[JPRidley]

Re: 91 48spl wont reach high rpm's in forward

could be either a faulty power pack circuit or a faulty SLOW sensor (speed limiting overheat warning) - most likely the sensor

 

[tashasdaddy]

Re: 91 48spl wont reach high rpm's in forward

choke lever up???? are you saying you can raise the fast idle lever with the motor in reverse? if so, you have something wrong in the control itself. that lever should not be able to move when in forward or reverse. by the way that is not the choke lever, it is the fast idle lever. you push your key in to activate the primer, your motor does not have a "choke".