Carb Overflow Problem

[SDJHAWK]

Good Afternoon,

Long time reader, four-time poster. After reading through all of the other posts about carburetor overflow problems and doing all that I could to repair what I thought was the issue, here I am posting for you help.

Last week my #1 carburetor began purging fuel out the overflow. I pulled out the float, checked it, looked at the needle seemed fine, but noticed that the float lever was bent at the bump stop contact point. Using the other float levers as a guide, I reshaped the lever to match the others, thinking that this would solve the problem (silly me).

I am still gushing fuel out of the overflow; does anyone have any other avenues for me to try? Any help would be greatly appreciated, especially since my wife hates it when I keep coming home stinking of fuel!

 

[Michael Oritt]

Where is the fuel level in the carbs in relation to the jet bridge?

 

[ThomP]

Sudden overflow situations, usually indicate crud in the fuel system not allowing the needle valve to seat. Do you have a good fuel filter near the carbs? Was the bottom of the fuel bowl clean? If your answer is yes, then I'd suspect your fuel line is deteriorating and bits of rubber from the fuel line after the filter are doing the evil deed. New fuel line? Then.... Hmmm, that's all I can offer. Hope it helps.

 

[SDJHAWK]

I am not sure, how do I check the level?

 

[dlamb43]

You could try replacing the needle and seat assembly with grose jets. I like 'em.Cheers, David

 

[SDJHAWK]

I was just monkeying with the float lever again and when the lever in is in its fully closed position the fuel stops over-flowing. Is it possible that the float, while not showing any leaks, could have lost buoyancy? Or may it be needle issue?

 

[MarkA]

If the float is "leaking", then you would hear or feel liquid inside of it when shaking it. The needle could still be failing. You may be putting more pressure on it manually to stop the flow than the float will normally put on it when the fuel is overflowing the bowl.

Mark

 

[Patrick67BJ8]

I was just monkeying with the float lever again and when the lever in is in its fully closed position the fuel stops over-flowing. Is it possible that the float, while not showing any leaks, could have lost buoyancy? Or may it be needle issue?

I think it's a needle/seat issue. For some reason the tolerances between these two parts are critical. I used to use Grose jets and they seemed okay for a while but I found out that the cars vibration was allowing fuel to get past the ball & seat.
Patrick

 

[Ed_K]

Do you have a stock fuel pump ? If not, perhaps too much pressure ?

 

[healeynut]

Any time you have fuel overflow problems one of the first things you can do is give the float chamber fixing bolt a quick tap or two with a spanner. That'll usually get it to shut off and keep it working for the rest of the drive.

If that doesn't work then you need to check your float for leaks. Pull the float out and shake it, if it has fuel in the float then you need to wither fix or replace the float.

Cheerio!

 

[AndrewMawson]

Plunge the float in warm water. If air bubble stream out then it has a leak.

I suggest though that having tweaked the float level (with the best of intentions!) then now you need to go through the level setting up procedure having either replaced the needle valve or lapped them with metal polish.

AWEM

 

[roscoe]

Don't forget that a blocked float bowl vent can cause the bowl to pressurize because the fuel level never rises enough to shut the valve off, before it allows fuel to squirt out the jet.

Jon

 

[AndrewMawson]

Don't forget that a blocked float bowl vent can cause the bowl to pressurize because the fuel level never rises enough to shut the valve off, before it allows fuel to squirt out the jet.

Jon

I knew there was something I was trying to remember that was an obsure reason for overflow !! Check that the fibre washer for the hold down banjo bolt hasn't been replaced with a standard one. It should have three lobes on the inner circle to allow air/ petrol vapour to escape and relieve the pressure. At a push you can take a standard fibre washer, and carefully file three relief notches with a rat tailed file to create an air passage from the float chamber to the banjo 'space'

 

[judperk]

Try loosing the bolt (slightly) that attaches the bowl to the top. Just induced the same problem after I tightened the bolt because it seemed loose. I let up on the bolt slightly and problem solved. Eureka.

 

[AndrewMawson]

Well in that case you definately need the special fibre washer - don't leave the banjo bolt loose or things will rattle off just at the wrong time !