Oil in carb bowls after winter lay-up.

1988 3 cyl. 90. First time this happened. I did see oil on the ground last year. I run the motor out of gas when winterizing but leave whatever oil is left in the engine mounted holding tank. It appears the air and oil in the tank expanded with the heat this summer and was force thru the oil pump, gas pump, fuel filter then into the carb bowls till the float rose. Does anyone know why this is happening recently? I plan to leave the oil tank cap loose next winter or possibly drain it.

Residual oil in the fuel will be left when the gas evaporates. Good reason to use a fuel additive to keep that from getting gummy. Some call it snake oil and won't use it. I have for most of my 60 years of boating. Never had a carb gum up from fuel residue in all 60 years. When I buy a used motor, first thing I do is rebuild with a factory kit. Then use fuel additives after that, and I use E gas, never had to rebuild that carb again. Running carbs out if gel is a good idea, but does not remove all of the fuel. Some us still in hoses and lines that eventually end up in the carb bowl. One thing that could help is to remove the drain screws under the carb bowl if your has those. Even spray some carb cleaner in there to flush it. Fuel additives are much easier though....

electricjohn said:

1988 3 cyl. 90. First time this happened. I did see oil on the ground last year. I run the motor out of gas when winterizing but leave whatever oil is left in the engine mounted holding tank. It appears the air and oil in the tank expanded with the heat this summer and was force thru the oil pump, gas pump, fuel filter then into the carb bowls till the float rose. Does anyone know why this is happening recently? I plan to leave the oil tank cap loose next winter or possibly drain it.

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Check the oil tank venting and the oil injection system. A sealed tank can build pressure with temperature changes, but it usually shouldn’t force oil through the pump and into the carbs. A sticking check valve, leaking oil pump, or a problem with the tank vent could allow oil to migrate while the engine sits.

Avoid leaving the cap loose unless the manual specifically calls for it. Check the oil lines, pump, and any check valves for leaks or failure. Since it’s a 1988, age related parts like seals and valves could be the cause.

Well as you fun that motor out of fuel the only think still pumping is the oil.

A friend had that problem. Turns out he was turning the motor over with the starter several times while in winter storage. As described above, the gas evaporated and the oil was left.

The oil pumping regardless of gasoline in the line is a problem I had with my engines when I got older and they sat a lot. Getting them started for the then current outing, took awhile for the gas to get to the cylinder (even with pumping the bulb up to firm) but the oil was pumping as long as the crankshaft was turning. Pre-mix solved that problem. If you used your engine frequently this problem didn't occur (for me).