will not rev

[Elsley]

Help<br /> I own a 83 Merc,40HP S/N 1004616 that starts no problem,idles rough but will not rev up properly it has new coils,pick up,brain box,new plugs,comp in both cylds is good,it appears to try to rev up but just wont do it,ignition or fuel any suggestions would be most welcome,thanks I know somebody will be able to help.

 

[JB]

Re: will not rev

Howdy, Elsley.<br /><br />We get this same question six or eight times a day.<br /><br />Giving the same advice over and over gets a little old, but I'll try it again.<br /><br />Crank it up on the earmuffs. It will sound okay, but that means nothing. Short out or pull each plug wire in turn. If there is no change that is a dead cylinder. If rpm drops or the engine dies that cylinder is making power.<br /><br />If all cylinders are making power, try spraying some fuel mix into each carb as you try to rev it up. If it picks up and revs that carb is gummed up, overhaul it.<br /><br />Let us know what you have found and we'll go from there if needed.<br /><br />Good luck.

 

[4link1955]

Re: will not rev

Also check the carb and make sure the high speed jet has not backed all the way out. I had this to happen on my 140 Evinrude last year.It would run fine at low speeds and just as soon as you went to full throttle it would act like it was going to go and then it would just flaten right out and not turn any more. <br />Jason

 

[cclemon]

Re: will not rev

A failing timing advance could also cause this problem.