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Carb spewing fuel? Fuel in oil?


lancemb

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66 Skylark, which only last year ran for first time in 20+ years, ran surprisingly well with minor help with exception of a small lifter noise. When starting it again today, the carb (Rochester 2bbl) started spewing fuel out a hole at the top, yet ran. I tapped on the carb a bit and the spewing stopped. However, the car was running rough like it had a miss, and the engine was noisier. I shut it off and check the oil - it was full but smelled like gas. Anybody know what was going on with the carb? How could it get fuel in the oil? Are these related? I am thinking so.

Sorry, I grew up working mostly on fuel injection systems! Now I need to learn more of carbs...

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Definatly float stuck from most likely dirt in needle and seat. Fuel system surly must have it's share of crap floating around including the carb. You can rebuild the carb as it probably needs it after 20 years sitting but the sticking float problem may continue till all the tank and line crap passes through. An inline filter may help to. Good luck

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When the float is stuck open--and it sounds like that's the case--fuel keeps pouring into the engine even after you shut it off, until the pressure is gone from the fuel pump. It runs roughly because the engine cannot burn that amount of fuel, so the spark plugs get fouled quickly, and there will also be lots of black smoke coming out the exhaust pipe. You need to change the oil if it has that much fuel spilled into it, although some of the fuel may evaporate as the engine warms up, but I would not want to run it long with gas in the crankcase. It will ruin a lot of expensive parts (bearings, etc.)

Pete Phillips, BCA #7338

Sherman, TX

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Thanks for the info. I shut it off when I realized what was happening, but unfortunately it ran for a few minutes before I realized what was going on; at first I thought it may have just been condensation in the distributor cap. Do you think it still may be okay once I change the oil, rebuild carb, and replace plugs?

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Lancemb,

Just another quick experience we had with regard to gas in the oil.

Dad`s 51 Nash (6 cylinder) ran great but when idling spit out oil from the vent tube. Like you, when checking, the oil level was right up but with lifter noise. Finally checked the fuel pump and the rubber diaphragm had a small hairline crack in it allowing gas to get into the crank case yet still able to pump enough fuel to the carb.

After 100,000 miles guess the rubber finally went. Could be due to the type of fuel compatibility with the older rubber also. Suggest when rebuilding your fuel pump ensure new diaphragm is the latest material not NOS.

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  • 2 weeks later...
Guest 57Roadmaster75

I agree, check the fuel pump for sure. I've seen this happen several times. The diaphragm rubber gives out and you can get fuel into the crankcase.

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