9.5 hp Evinrude gas coming out of exhaust

Beek14 · #1 June 16th, 2009, 03:53 PM

I run a 1964 9.5 hp Evinrude on the back of one of my little boats, and I notice when idling, or very slow speeds, a bit of gas is coming out of the exhaust, and I was wondering what would cause that. Am I right to believe it may be the fuel pump? Too much gas being sent in and it getting unburned? I would just like to fix it before i spray too much into our lakes!! Any ideas would be great..

Cricket Too · #2 June 16th, 2009, 03:58 PM

My guess is that the cause of that is that it's a 2 stroke engine. All carbed 2 strokes shoot unburned fuel out of the exahust, it's just part of how the exhaust is scavenged by the intake charge, no way to avoid it, at least in carbed engines anyway. There is also unburned oil being shot out as well with it, not to mention the burned oil that comes out of the exhaust.

Not much you can do about that.

Beek14 · #3 June 16th, 2009, 04:14 PM

Well, that's kind of what I thought. I just wanted to make sure though.. And since it's older it might be more of a reason there as well.

Cricket Too · #4 June 16th, 2009, 04:24 PM

Yeah possibly, if the compression is lower you could be spitting more unburned fuel and oil out. You can run a decarb treatment and it may help a little but 2 strokes are just dirty engines.

I thought a lot of lakes didn't allow them anymore.

Beek14 · #5 June 16th, 2009, 05:08 PM

Well, 2 strokes are the most popular outboards out there. It's pretty tough to say you can't use a two stroke in lakes because then most people wouldn't be able to get on the water without having to invest in a brand new motor. When even a couple of years ago people were still buying brand new 2 stroke outboards for their rigs. Imagine how po'ed those people would be having someone say sorry you can't use that. What they are doing is trying to ban creation of new 2 strokes (if they haven't already) and convert them all to 4 strokes. Hoping that eventually over time, they will rid 2 strokes all together.

Cricket Too · #6 June 16th, 2009, 05:13 PM

Yeah it's a well known thing that 2 stroke carbed engines are being discontinued by most if not all companies.

Could have swore that I heard that some small lakes were outlawing 2 strokes though, maybe it was just here in NY.

Beek14 · #7 June 16th, 2009, 05:17 PM

I suppose that could be... They haven't over here in MN.. but I guess that isn't to say they couldn't have done something like that other places. What we have up here is the BWCA Boundary waters canoe area where they just ban motors all together ( in designated areas ).