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carb rebuild and now I have gas in the crank case mixed with the oil, any suggestions?

naterion

New member
We have had Nissan service out 3 times for a rough running 9.8 Nissan. They rebuilt the carb and it worked for a day, now we have gas in the crank case mixed with the oil. Any help would be greatly appreciated!
 
I too have discovered a large amount of fuel in my crank case. I was having a high speed problem - it operated well at low speed and idle - I pulled the carb to check and found it clean. I re assembled, and found the fuel line bulb would not get hard and expect I was pumping into the crankcase....??? Is this a fuel pump issue?
 
I too have discovered a large amount of fuel in my crank case. I was having a high speed problem - it operated well at low speed and idle - I pulled the carb to check and found it clean. I re assembled, and found the fuel line bulb would not get hard and expect I was pumping into the crankcase....??? Is this a fuel pump issue?

Probably. Pull the fuel pump and prime. If the diaphragm is shot, fuel will leak out near the pump pushrod.

Always disconnect the fuel line at the motor at the end of the day.
 
I checked the fuel pump and detected no leaking. I am expecting a gush. I starts easily and will run well but then increase in RPM with no additional throttle. I also noticed that there is varying amounts of moisture in the exhaust. Is this normal?
 
What is "expecting a gush"? If you have the pump out of the motor (but connected to the carb and inlet, and prime up, if it does not leak at the push rod, the pump is not leaking.

If the bulb will not firm up, either you have air in the line (such as due to a bad o-ring at the tank connector... or bad check valves in the bulb, or the float valve in the carb is not seating... which would lead to flooding, steam in the exhaust, and gas in the crankcase, among other issues.

Are you saying that when idling around say 1000 rpm, suddenly, the motor climbs in RPM? If so, the carb idle speed may be set too high, to cover-up a poor idle circuit. If that is the case, the carb needs a Proper cleaning.

Some steam coming from the idle relief port is normal, and most pronounced in cool weather, shortly after a cold start. You will also see it when the humidity is very high.
 
Re: "gush" when the bulb didn't firm up, I figured I was pumping all that fuel to the crankcase. There was ultimately at least 8 ounces over the dipstick level so it was a significant amount. I drained and flushed and refilled the crankcase. The bulb did firm up and all seems well now, except for the surging RPMs.

As much as I enjoy pulling things apart and tinkering, I think this needs some attention from a pro.

I appreciate your help.
 
I don't comment on small outboards (9.9's)because I don't service enough of them but, I was on a service call on a Honda BF30 with 5400 hours on it. The owner installed a new portable fuel tank, and developed a rod knock due to gas in the crank case.

Here is what I found, maybe this will help....... The new portable fuel tank is un-vented and requires a fuel demand valve, he did not have one. With the tank hooked to the engine and the sun beating down on the the tank, it swelled like a balloon and pressurized the fuel system forcing fuel past the carb float needles and into the intake past the rings and into the crank case.
 
The EPA tanks are not unvented. That would make them a bomb. They regulate at about 5 PSI, which is above the limit for the float/needle/seat. That is why you must disconnect the fuel line at the carb (which you want to do anyway to idle the carb dry). Yes, they will swell up like a pillow in the hot sun, and crush like you stepped on them at night. Thank the EPA for that crap.

Demand valves may or may not work. But in any event, disconnect the fuel line at the end of the day and you will be OK.

FWIW, many owners remove the "duck bill" valve from the EPA tank caps of Scepter tanks, making them regular, vented tanks. Technically illegal, but it solves a lot of issues. Not doable on an attwood tank, as you don't have access to the valve inside the cap.



I don't comment on small outboards (9.9's)because I don't service enough of them but, I was on a service call on a Honda BF30 with 5400 hours on it. The owner installed a new portable fuel tank, and developed a rod knock due to gas in the crank case.

Here is what I found, maybe this will help....... The new portable fuel tank is un-vented and requires a fuel demand valve, he did not have one. With the tank hooked to the engine and the sun beating down on the the tank, it swelled like a balloon and pressurized the fuel system forcing fuel past the carb float needles and into the intake past the rings and into the crank case.
 
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