Evinrude 9.5 Sportwin power loss

I am new to this. I have inherited a Mid 70's 9.5 HP sportwin. It's mint with only 2 tanks of gas through it ever!<br /><br />I have found after 3 tanks of gas, a steady but decrease in power at full throttle. It Idles, trolls well at low speeds, even has high rev's when not in gear. I figure it is only acheiving 50% power at full throttle when in gear (no smoke).<br /><br />Could my carb just need to be rebuilt?

Re: Evinrude 9.5 Sportwin power loss

You need to mix oil with that gas, you knew that allready though, huh?<br /><br />If it's spend so much of it's life just sitting around it may have dried gasoline deposits starting to dislodge in the cab and clogging the jet.<br /><br />Just a thought.

Re: Evinrude 9.5 Sportwin power loss

Some more information would help. How's the compression feel? Is the motor pumping water? (There should be a stream of water coming out of the spitter on the port rear of the lower motor cover.) Is the motor cooling? (The cylinders are cooled by a water jacket, and the surface should be about 140 degrees F - you should be able to hold your hand on it for about 5 seconds.) Is it running smoothly at all rpm ranges, and if not, where is it stumbling? Let us know...

Re: Evinrude 9.5 Sportwin power loss

1) yes, I add oil to the fuel mix as per the owners manual. I meant "no smoke" as in excessive smoke....that my indicate ring damage???<br /><br />2)Water pumping out just fine. It runs fairly smoothly through all rpms. I can achieve the high full throtle rpm when the motor in not under load.

Re: Evinrude 9.5 Sportwin power loss

continued.....<br /><br />The engine stumbles a bit during a very slow troll, but the rich/lean adjustment seem to remedy that after its been warmed up. Cold starting seems fine. Full choke, 1 or 2 pulls and it starts.<br /><br />It runs smooth at max throttle, but the higher rpm and tourque under load are no longer present and boat does not get up on plane any more. It actually feels like "If you could just give the throttle a "half a twist" more....

Re: Evinrude 9.5 Sportwin power loss

Hi Gruntr2000,<br /><br />How's the bulb when you're running? Firm or collapsed?<br /><br />Give the bulb a squeeze when you've got her cranked. DO the rpm pick up?<br /><br />Remove the cover and look for excess/leaking gas on or around the carb.<br /><br />Let us know what you find. The more detail the better.<br /><br />There are plenty of guys around here that can point you in the right dircetion if they have enough info.<br /><br />My first GUESS would be a fuel delivery problem. You might consider replacing all of the OLD fuel lines (the one from fuel connector to pump can be a bear at the connector end), remove and clean/rebuild carb.<br /><br />Good Luck<br />HAVE FUN!

Re: Evinrude 9.5 Sportwin power loss

Totally stumped here.....This motor has been in storage for over 25 years and has less than 500 hrs on it. I'd say 350 hrs by me over the last 6 years...<br /><br />If it "delivers fuel"...I've replaced it<br />It it "electrical" I've replaced it<br />Fuel mix 50:1<br /><br />"Decarboned" it, Pulled the head, cylinders look good. New head gasket.<br /><br />Runs like a banshee (in neutral) in the tank with cowl off. RPM's drop when cowl replaced.<br /><br />Trolls fine on the lake, but won't go full out. I'd say only 50%, with cowl on and marginally better with the cowl off ....WHY?!?!

Re: Evinrude 9.5 Sportwin power loss

...sorry... forgot to add the the water pump is good too.