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15 HP Evinrude 2 stroke

M

mrtmaag

Contributing Member
"This motor has seen a lot of

"This motor has seen a lot of good use. We have logged many hours on it and I would like to clean it up and help it last a lot longer. It will idle all day long without dying but sometimes after using it for 1/2 an hour or so it hesitates quite a bit when you give it some gas. It has been used very frequently so the gas probably doesn't have a chance to go bad. Also it looks like a little oil is leaking out the foot. I am quite mechanically inclined, what would you recommend with this motor."
 
"Troy, when you say "hesit

"Troy, when you say "hesitates quit a bit" is it "missing"? or just slow to respond? or does it kinda surge it's way back up to higher rpm?

You second issue, leaking oil, lower unit oil? (which would be a gold colour) or is black oil (kinda like dirty motor oil)???"
 
It is slow to respond and kind

It is slow to respond and kind of surges to higher rpms. If you run it full throttle it surges and eventually opens up with full power.

The second issue of the leaking oil is kind of like dirty motor oil that is almost dark gray or black.
 
if it's gray in color at a

if it's gray in color at all then you have water getting into your oil..........head gasket could be a culperate........which would explain the power loss. my marine gear oil is dark green!! Graham........is it suppose to be GOLD? My experience is that a little leakage of oil is ok......as long as you keep it filled!! I've seen evinrudes that were filthy with oil and ran great......I've personally seen very clean outboards that ran like crap!!
 
"Troy, the surging is "usu

"Troy, the surging is "usually" a fuel system related problem.

I would start checking out the "easy" things first.

Inspect the fuel pick-up in the tank for a slight clog and make sure the tank vent is working properly (opening fully).

Check your hoses and connections - are the lines old? Some get eaten up a bit by the new gas additives causing them to collapse internally.

Check the fuel filter.

If all are ok and functioning like they should, next I would check the fuel pump - particularly the diaphram for perforation, tears, general wear and then the carb.

Despite the fact that you run it often you may have got some crud in the carb which is partially blocking the jet - besides, a cleaning never hurts...

The "oil" that is leaking is most likely just burnt/unburnt marine oil. The exhaust leaves all kinds of nasty deposits inside the exhaust housing (leg).

The more you run it, the more goop that builds in there. When the motor is sitting out of water this "gunk" slowly slithers down the leg to the top of the lower unit and leaks out either the drain holes (near the cavitation plate) or through the exhaust in the prop hub.

In either case, nothing to worry about - it can appear anything from "black" to something that looks like (and has the consistency of) chocolate milk shake
"
 
"Thank you for the advice. Th

"Thank you for the advice. The oily stuff is leaking out the drain holes and the prop hub. It especially leaked out last summer when it was really hot and the boat was out of the water. It sounds like it is probably just exhaust soot.

The surging is most likely a fuel related problem as you suggest. the tank and fuel line are very old, I wouldn't be suprised if there is a vacuum leak in the host connections even. I think I will get a new tank and hose as these have more than paid for there many hours of service. I will try this then go in for the more difficult stuff."
 
"Yes, Troy, you will get that

"Yes, Troy, you will get that gunk leaking after running long periods or especially after it is first started if the motor has been layed up for a bit - totally normal.

And if your lines are old the alcohol added to the fuel now may be doing a number on them - for a few bucks a modern fuel line may be the cheap fix..."
 
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