'91 48 Special looses power at WOT

[N4WJT]

I have a '91 Johnson 48 Special that idles fine but sometimes when you are planing off or shortly after you get planed off motor starts to 'buck' with rpms slowing and then increasing in cycles. If you don't pull back on the throttle, it will eventually die. If you do pull back, it will idle fine. Even if you pull back to 3/4 throttle, it will run fine of a few seconds then start to buck.<br /><br />I've traced fuel system up to the carbs. Fuel supply is OK. Thinking of rebuilding carbs if I can find kits. Any other suggestions?<br /><br />Billy

 

[Solittle]

Re: '91 48 Special looses power at WOT

The carbs are the place to start. Use a manual if you have never done it before.

 

[N4WJT]

Re: '91 48 Special looses power at WOT

Thanks 'SoLittle'. I recently purchase the repair manual but haven't been able to find the carb rebuild kits from this site. I'm suspecting it may be the 'high speed' inlet. I noticed from the manual the carbs have inlets for 'low speed, 'intermediate' and 'high'. Someone suggested the powerpack but from the manual my motor has a UFI ingnition. Am I correct in that I don't have a 'powerpack'?

 

[fireman57]

Re: '91 48 Special looses power at WOT

Napa can help you with parts. You might try pumping the primer bulb when it bucks to see if it stops it. that definitely would indicate fuel rather than electrical problems.

 

[N4WJT]

Re: '91 48 Special looses power at WOT

Thanks 'fireman57'. I had my fishing buddy try pumping the bulb and it didn't seem to help. I've removed the single screw from the pump and check the screen. It was clean. I reassembled the pump and remove it from the powerhead, pumped the bulb until tight but no gas leaking through the vacuum hole so I assume the diaphram is OK. The only thing that concerns me about rebuilding the carbs is the linkage and throttle adjustment. Can they be disconected and reinstalled without effecting the adjustments. Or do they possilby need adjusting?

 

[fireman57]

Re: '91 48 Special looses power at WOT

If you have a manual then after you rebuild the carb go to the link n sync portion and follow the instructions to the letter and that job should be complete. If you have a Seloc manual it may be kind of generic. There are posts here if you do a search from the top of the page. There is a great post by Joe Reeves on setting carbs if you do a search. You still may want to check your spark when it starts to buck.