evinrude 15 hp fouling bottom plug

[warmachine]

Please help! I have been fighting this motor for a month. It has new coils and plug wires making good spark, rebuilt carb, New head gasket, New base gasket, e3 12 spark plugs, I put an electric fuel pump on it. Reed valves were good although some of the ports had old paint in them but I think that's for the old pressure tank so that shouldn't matter. With clean plus it runs like a scalded dog and when I come down to idle it instantly fouls the bottom plug. Is like it has too much fuel. Compression is good running 50/1 premium non ethanol. What is wrong with this thing?

 

[warmachine]

Re: evinrude 15 hp fouling bottom plug

Could it be the fuel pump forcing too much fuel in? If so then why is it not killing both plugs? I am ready to enjoy this thing is been allot of work.

 

[warmachine]

Re: evinrude 15 hp fouling bottom plug

I figured I could regulate the fuel pressure with the carb needles, but maybe not?

 

[warmachine]

Re: evinrude 15 hp fouling bottom plug

I think I need to ditch the electric fuel pump and try a diaphram pump. But what pump to use? Where do I start? I just need confirmation on my suspicion about the electric fuel pump. Would a diaphram pump not over gas at idle because it would follow engine rpm and not be a constant high pressure?

 

[warmachine]

Re: evinrude 15 hp fouling bottom plug

I built a new boat trailer, fixed up a John boat, rigged it to the t for bowfishing, and thought my motor was done. My wife is about to kill me and I have a bowfishing tournament on Saturday. So any advices would be greatly appreciated.

 

[warmachine]

Re: evinrude 15 hp fouling bottom plug

BTW is a 1956 evinrude fastwin

 

[Rick.]

Re: evinrude 15 hp fouling bottom plug

Your fuel mix should be 24/1. Go back to the pressure tank and forget the electric pump. I don't know your engine well enough to be much help. Best of luck. Rick.

 

[warmachine]

Re: evinrude 15 hp fouling bottom plug

I went to a vacuum fuel pump and still same result. I did the conversion correctly, fuel pumps as it should. Still once I idle, a wet plug that won't fire. I did notice that the spark is a bit weaker than the other, but it is firing. Could this be a condenser going bad? Also one of my sliders that run on my crankshaft is a little worn but I still gapped it to .020 like I'm supposed too. It looks more tilted than the other, another words is not lining up flat like the other. Should I replace points and condensers

 

[the machinist]

Re: evinrude 15 hp fouling bottom plug

The points arm can be tweeked (straightened) so the contacts fit better, sure wouldn't hurt. If in doubt & you are this far the low price of condensers would be another thing to cross off your list. And if you are there, then change the points also.

You could also have a corroded wire anywhere on the lower cylinder, even inside the spark plug boot.

 

[warmachine]

Re: evinrude 15 hp fouling bottom plug

Well thanks I just ordered a point and condenser kit from vintage outboard. I will post result later this week.

 

[warmachine]

Re: evinrude 15 hp fouling bottom plug

Well I put in New points and condensers, initial result was I thought it was fixed, runs good, then she fouled the bottom plug. Kit did make motor much smoother, but still the issue. I pulled the intake manifold and flipped my reed valves right on the water. thought maybe one was weak. Did not fix it. This problem has got to be in my carb. But what? Is got a brand new kit in it. Compression is 100 on the top and 97 on the bottom. This is a normal reading I assume?

 

[warmachine]

Re: evinrude 15 hp fouling bottom plug

Dang I think I figured it out,I bet my fuel slider is adjusted all the way out and is keeping my carb open at idle. When the timing decreases as I slow the engine it over gases it and fouls only the bottom because it gets fuel first. Let me adjust this and test.

 

[tacoma_2002]

Re: evinrude 15 hp fouling bottom plug

I see you put a electric pump in...however...

I have noticed that with a hole in the diaphram of a manual pump, it floods the lower cylinder. Sounds like its getting too much fuel from the pump. Pick up a in-line FPR from your local Advance Auto Parts (or other parts house) and try regulating the pressure manually to see if this fixes your problem.

 

[warmachine]

Re: evinrude 15 hp fouling bottom plug

That did not fix it. I just put a brand new mikuni pump on this thing. No way is my fuel pump.

 

[warmachine]

Re: evinrude 15 hp fouling bottom plug

I ditched the electric pump because that was my first thought too

 

[warmachine]

Re: evinrude 15 hp fouling bottom plug

Ya know that regulator might just do the trick, I've been mulling it over in my mind and I think I'll try that first thing tomorrow.

 

[ultra353]

Re: evinrude 15 hp fouling bottom plug

Make sure coils are correctly lined up on the bosses. If one is set back too far it will have a weaker spark as you indicated

 

[AlTn]

Re: evinrude 15 hp fouling bottom plug

fwiw.. 1978 factory manual/15hp..fuel pump test w/gauge tee'd into line from f/p to carb.....fuel pressure...600 rpm/1 psi...2500-3000 rpm/1.5 psi.....4500 rpm/2.5 psi

 

[nwcove]

Re: evinrude 15 hp fouling bottom plug

Why the heck are you running E3 plugs and not the correct champions?????

 

[warmachine]

Re: evinrude 15 hp fouling bottom plug

You guys are giving good info, my coils are lined up perfect, I adjusted the brand new regulator all the way down to 1/2 pound and still it fouled the plug. Maybe my carb float is sticking. Is the last thing to check. Everything else I know is right