40hp Envin bucks at High Speed

[bud659]

On a 1990 Envirude 40hp, when the engine is at high speed it will buck. The engine will run at high speed for about 10 seconds then the engine will decrease in RPM and eventually stall by itself. It feels like it is some sort of fuel pressure problem but don't know where to begin? I want to make sure of the problem before I spend any $$$.<br /><br />At low speed it runs fine. At a cold start, it will run for a few seconds then stall. After a few more starts, it will finally stay running. <br />The problem is mostly stalling at high speeds.<br /><br />Appreciate any help. Thank you,

 

[DJ]

Re: 40hp Envin bucks at High Speed

bud,<br /><br />What happens to the primer bulb when it stalls? Does it collapse?<br /><br />If so, try running the engine with the fuel filler cap loose.

 

[bud659]

Re: 40hp Envin bucks at High Speed

thanks Admiral for your reply.<br /><br />Its funny how you should ask that. At low speeds, the ball is pretty firm. However, at high speeds when the bucking happens, the ball is squeezed in. It is like I sat on it or something.

 

[OBJ]

Re: 40hp Envin bucks at High Speed

Bud....check your gas tank for ventilation.