sudden loss of torque...no speed

[Neebar]

I have a 1961(62) 40 HP Evinrude Lark IV. Just rebuilt the carb and did a tuneup (wires, plugs, fuel filter). Took the boat on the lake worked alright (seemed to lack power in full throttle). Took the boat for a spin without the kids at teh end of the day and it ran great....then the problems started. While in a tight turn I heard what seems to sound like an exhaust backfire (not to sure though) then I backed the throttle to the start position the engine idles alright ...moved forward ...then I tried to throttle up and no power...I could hear the carb open and the engine sped up a little but no more speed. I was able to troll around at a slow pace but I was no t able to get much more speed than that. Any ideas?

 

[surlyjoe]

Re: sudden loss of torque...no speed

sounds like your high speed mixture is too lean, try richening it up a bit. if theres gunk in the carb, you will probably have to clean out the bowl, if thats the case you should just rebuild it. they are real straight forward. also check to make sure the rubber bushing in the prop didnt slip, you might do that first...

 

[Walker]

Re: sudden loss of torque...no speed

Basics. Compression, spark, fuel<br />Start with a compression test.

 

[Neebar]

Re: sudden loss of torque...no speed

I got the compression test etc done before I rebuild the carb..I think the reading was was 110 and 115. There's spark and the fuel is reaching the carb. Since I've just rebuilt the carb it should be clean...could dirt and gunk from the fuel lines/gas takn clog it up that fast? (it was the first day out since rebuilding the carb). I'll double check the throttle needle...maybe it came loose/or out of adjustment.<br /><br />Is there a chance that something could have broken? The boat is statring/idleing fine. When the trottle is in the start position and I'm idling, I shift it into forward and it goes...I can throttle a bit above that but then that's it...the engine doesn't rev past that speed.<br /><br />I'll readjust the throttle and test it out the next time I'm on the lake...or is this comething I can test at home whit the hose connection/set-up on the water inlet on the bottom of teh engine?<br /><br />Thanks for all of your help...this forum has been an amazing recourse...especially the previous posts. This is great!