Leaky Motor

[Sean McGuire]

Not a true DS question, but I have a related question. I have a Nissan 2.5 hp 2 stroke motor that came with the boat when I bought it a couple years ago. The problem is that the motor leaks gasoline when it isn't running. I have checked the gas tank for cracks and all the lines and fittings but can't find the source. I thought at one point that pressure was building up in the gas tank and pushing gas out the carb so I left the cap vent open, but it still leaks. Over the season, I probably leak more gas than I burn. Any suggestions?

Thanks,

Sean McGuire
1984 DS II "Iona"

[adam aunins]

If you could find a UV die that is safe to use with the fuel you could then use a black light to track the leak down. If your carb has a float and needle I would check them also. If worst comes to worst you can hold a lit candle around it until it lights off, then you'll know where the leaks at.

[algonquin]

I would go ahead and replace the gas lines and clamps. Gas doesn't need much of an opening to leak through and you can cheaply replace the lines and clamps and eliminate them as a cause.

[SUNBIRD]

If your NISSAN 2.5 is the same as my old Johnson 2.3 (I'm 99.9% sure it is, from looking at these motors) then the drain plug in the carburater bowl may be leaking (a hex-head screw on bottom of bowl). Do you shut off the fuel valve on the side of the motor while not using it? I always did, and I never had a problem. Otherwise, check all connections, and check the hoses since the new alcohol-enhanced gas can affect fuel lines and seals.

[hriehl1]

The Nissan was made by Tohatsu (who also made Mercury and Mariner)... they're all basically the same. I think they manufactured for Johnson and Evinrude too.

99% likely it is a sticky carburetor float and needle-valve assembly. Or needle-valve doesn't fit properly in its seat. Happens once-in-a-while on my '86 Merc 2.2 and often on my '83 Mariner 2. Sometimes a thump seats and seals it, though I'm diligent with the fuel shutoff valve too to avoid spills.

Though before opening the carb bowl to check the float and valve, do see if there is a drain-screw on the bottom of the bowl and be sure that's not leaking.