Holley 1 barrel flooding

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CARS

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Before I tear into my carb, what causes a carb to dump excess fuel?

Last week I noticed a "fuel smell" and parked the car after I made it home.
Drained a couple gallons of gas with the 5 quarts of oil.... Not happy. It was literally shooting out the valve cover! (she may be clean now, but she is also going to need some work after this).

Took the carb off and looked it over (while the crankcase was drying out), didn't notice anything hanging up. No gumming, everything seemed free/normal. Don't really know what to do.

Any thoughts???
 
Flooding is usually caused by the bowl over-flowing because the fill valve is not closing tight. Very similar to a toilet tank level control. With the carb on the car, it is easy to remove the needle with the inlet fitting. A flare wrench is best to not damage the tube nut. Remove the needle and look for crud or a degraded rubber tip. Also, your float may not float anymore. Replacements are available, but harder to find.

If the tip checks out, remove the fuel bowl to check for contaminants or a bad float. Use a flat screwdriver with a thick tip to not bugger up the screwheads. Assuming your filter still works (change regardless), you might have chunks of rubber from inside the fuel lines. If you replace, use the special "fuel injection" hose since it has better rubbers that stand up to ethanol, etc in gas today.
 
Well mine did that i just got a newer carb lol im not good with them so im no help here .. now my val had set a year and was now getting gas so i took a wrench and taped it alitte and it started picking it up .... it mite work both way i think i got lucky i dove it a year after that then sold it after the crash
 
Mechanical fuel pump? I've seen diaphrams rupture and pump a crankcase full of gas (different engines, different manufacturer, though). The car would drive OK, but oil pressure would quickly drop.
 
The carb kit arrived at the shop this morning and I replaced everything. The float checked out ok, as did all the diaphragms.

The inlet needle was free. Actually too free compared to the new one. I wonder if the "slop" in it caused it to stay open or leak???

Thanks for the help guys. I'll bolt it on tonight, finish the oil change and see what it does.
 
I would bet on the fuel pump with that much gas in the crankcase. If that was all caused by the carb, you'd notice it running rich by black smoke out the tailpipe or it dripping off the throttle shaft.
 
cudamark said:
I would bet on the fuel pump with that much gas in the crankcase. If that was all caused by the carb, you'd notice it running rich by black smoke out the tailpipe or it dripping off the throttle shaft.
Click to expand...

Doesn't a fuel pump either pump X gallons a hour or nothing??? How would it ever "over-pump"???

I have heard of older engines (Flathead era) that would do this. Maybe I should read up on how a fuel pump pumps?
 
Something just dawned on me... Are you thinking that the pump is leaking directly into the crankcase???
 
CARS said:
Something just dawned on me... Are you thinking that the pump is leaking directly into the crankcase???
Click to expand...
Yup, it will syphon fuel from the tank right throught a bad diaphram and into the crankcase.
 
Yes. Well-made slant-6 fuel pumps (getting harder to find) don't fail often, but when they do, squirting gas into the crankcase is the most common failure mode. Not through any kind of syphon action, but with even a tiny hole or tear in the diaphragm, every time the pump is actuated a shot of gas goes right into the crankcase.
 
Well, I had two that the gasoline would siphon through a bad pump. I was changing the oil and filter because of the fuel dilution and the "oil" just kept draining out of the oil pan and into the drain pan. Not pouring through, but a steady 4-5 drips a second that wouldn't ease up. When I realized that it wasn't just oil but mostly fuel, I started pulling the fuel pump. As soon as I disconnected the fuel line from the tank, it broke the siphon and stopped draining through the fuel pump. I think it was a combination of high fuel level in the gas tank, bad diaphram, leaky valves, and the angle the car was sitting but the same thing happened to me twice so it's not a complete fluke. One was a '64 Dart and the other was a pickup with a cab tank.
 
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