Fuel Vent

[maxt]

I did something really stupid this weekend, I have a 40hp 63 evinrude, which was on a 15' fiberglass boat. I bought the boat and the engine about 3 years ago and just let it sit. Well, finally a couple of weeks ago I took it all apart, and restored everything. I also took the whole engine apart, changed the head gasket(cylinders had no scratches on it), rebuilt the fuel pump and the carb. Changed the points and spark plug wires. Also cleaned the whole lower unit, and everything looked good. Changed the water pump. Well, I finally put everything back together, and started the engine in a bucket. It started right up and ran perfect, I leaned the needle valve until the engine started dropping rpm, then i richened it back up, but i noticed that no mattter how much i would rich it, it wouldn't make a difference. It ran good at idle, so i went to the lake to try it. Well, i was pretty dissappointed. I know 40hp engines are small, but the boat which is about 600lbs would barely go. It wouldn't get on a plane, and the wind would feel like somone was just barely blowing in your face. So i was about to just go buy a new boat, when i came across a post here where a guy said his 90hp wouldn't have any power wide open either, and one of the suggestions was that he should make sure the fuel tank vent was open. That's when i felt really stupid. The vent on a plastic fuel tank was closed. I know that would keep the engine leaned out to the point where it wouldn't get power, right? I'm new at this and i don't really know what speeds to expect. I also was runing the engine for about an hour, and noticed that i barely used any fuel at all. I just wanted to double heck that leaving the fuel vent closed would do this. What speed should i expect from this engine, or should i just go and buy a new one? <br /><br /> Thanks a lot for the help in advance! Max

 

[Capt DHD]

Re: Fuel Vent

Hello Max;<br />Don't buy a new engine, Yet. By your description you only have one needle on the carb to adjust. Am I correct? If so, I think you need to clear the high speed jet that exists in the carb bowl, this may be your problem.<br />If the jet is partially plugged it will allow enough fuel for idle (all the fuel reaching this engine comes through this orifice) but may not allow enough to run at a higher rpm. Before you put this engine on a heap, check this.<br />Any fuel restriction could cause your symptoms so a closed vent is not out of the question, but I think you would have noticed the shape of the tank changing, they tend to inplode some. <br />I hope this leads you to your problem.

 

[maxt]

Re: Fuel Vent

Thanks for the help,<br /><br />I rebuilt and cleaned the carbs, so they should be clean. But i didn't think of the fuel vent until the next day, when i was taking out the tank. It was closed the whole time. I had to troll for a while out of the area before i could give full power, but when i gave it full power, it didn't have any, and one time it did the lean sneeze and died. Everything was rebult and it should be clean. But since i trolled for probably 5 minutes that would be enough time to make big enough suction in the tank to lean it out at full speed wouldn't it? Now i'm worried about that i burnt a piston and rings with it lean. I had a 32:1 oil mixture. You don't think that runing it lean would have hurt any of the bearings do you? The most the engine would run to was about 1500 rpm. It still started great and idled good. Should i get new rings or should the ones that are in there(new ones) be ok? I can't check them becuase i am away from home for 3 weeks, but should i go ahead and get the parts?<br /><br />Thanks again, Max

 

[corm]

Re: Fuel Vent

Hi Maxt,<br />The Capt is right,save your money.Test run it<br />with the vent open. If problem is still there<br />squeeze the primer bulb to force fuel into the carb to see if that helps. On land turn key OFF shift motor into foward gear while turning the prop, push gas lever to wide open, and visually check to see if the butterfly is in the horazontal wide open position. Some times the link arm between the spark advance and carb gets bent and the motor won't run past a fast idle.<br />Your bearings, pistons, rings,ect,are alright. Unless the motor siezed up on you.<br />32-1 is richer than you need in that motor<br />50-1 is ok if you use TC3W oil from a major outboard motor co.<br />Let US know how it goes.<br />...have fun...corm

 

[maxt]

Re: Fuel Vent

Thanks for the help corm and capt. I used 32:1 just to be on the safe side that first time (good thing considering it was lean with the vent closed). The butterflys do open. I checked that. I was just worried about a burned or scuffed piston since it was leaned out. Will run it when i get back home. Thanks again - Max

 

[suzuki40]

Re: Fuel Vent

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