Carb. Gas Leak

[nichols617]

Yesterday, starting out on a nice day run, the truck bucked and quit. When I opened the hood gas was running out of the bottom of the carb. I start the truck with an electric pump and then shut it off. Did I stick the float or blow the power valve? any idea?
thanks, Stu

[Dick's Hot Rod Place]

Crud in the needle and seat or the float filled and sunk. Power valve could have blown if you had a nice backfire when you started it. All 3 items are easy to check. Also, if you don't have a regulator with that electric pump you may have simply blown passed the needle and seat.

[nichols617]

I'm going to pull the carb. this pm and check. I'll check the float first.
thanks!

[Dee]

Take a good look at the economizer valve while you have it apart.

[ken ct]

Your lucky you didnt have a fire ,i wouldn't have started it with all that gas leaking out and the gen. sparking away right in front of it. Man you are lucky.ken ct. Not a brite idea.

[nichols617]

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How can you tell if the power, economizer, valve is bad? I have it apart.

[G.M.]

What was the outside temperature and the engine temperature when you had this problem? Don't rush into tearing things apart before trying to find the cause. Fuel pressure in the 7 to 8 lb range will push through the needle valve, there is not enough up force on the needle valve from the float to over come that fuel pressure. When this happens fuel spills over the top of the bowl. The temperature of the outside of the fuel storage bowl in the carb, this gives you a good idea of the fuel temperature. When this new fuel gets up in the 120 to 125 range on the bowl it is getting close to boiling and flooding over the bowl in the carb. This usually happens after it is shut down and the temperatures rise. In real hot weather, engine up near the 200 range this can occur in stop and go traffic or at idle. Under these conditions you will usually get poor power in slow moveing traffic and in extreme conditions lose of power below 50 MPH. Above 50 MPH there is enough gas flowing through the carb to prevent boiling. After refueling the cool gas will almost eliminate the problem as long as the fuel is not getting heated on it's voyage from the tank to the carb. G.M.

[Dee]

Power valve check: with the valve in place and the bowl plugs in fill the bowl about half way with gas. Look for drips of gas from the valve. Any moisture of gas indicates a leaking gasket or leaking diaphragm.

[nichols617]

Thanks, guys! Always good advice here!

[G.M.]

What was the outside and engine temperatures when this happened? There is a recent history of these problems. It would be good to get details of conditions when this occurs in order to solve this problem and help others. G.M.

[flatjack9]

I doubt it would be the power valve. More likely the float needle.

[nichols617]

It was a mild day here in charlotte. About 60.
Do I take the float hinge pin out, to get to the float needle?

[Dee]

Yes.

[ken ct]

Remove pin take out float,check in a pan of hot water for bubbles [leak]. remove brass fitting and install a old style steel needle and stake needle to fitting by placeing seat on work bench[wood] and hitinserted needle with a lite hammer blow.To form a good seat. and replace. Set float @ 1 7/16 top upside down on bench with no gasket. ken ct.

[nichols617]

Thanks, Ken