Overfloating problem SU

[UHR850]

After about 8 months it was time to start my engine up, it has a twin SU Hs2 set up.

After starting the engine the float chamber kept on over floating. Any ideas what to do ?
The floater is not leak so this is not the problem.

Kees

[IslandBlue]

Check the float and needle valve for a start, even a a small piece of debris in the valve will stop it from sealing and the bowl will keep filling...

I had this after my car was laid up for a while, I got very good at stripping down the float chamber lid and valve assemblies by the side of the road until I installed a fuel filter.

[UHR850]

Thanks, lucky it's in my garage and the filter is already in it

Kees

[UHR850]

done, problem solved.

[UHR850]

Still overfloting every ting is clean so why and how to solve this

[UHR850]

Mybe the wrong flote ?

[woodypup59]

One of my cars often does this if it hasn't been used for a bit.

I've tried several needle valve types without a definite result.

As I have a fuel pump switch I turn it off for 30s while still driving, and i turn it back on it usually behaves.

[Peter Laidler]

Take the float head off the carb, attach a piece of pipe to the inlet pipe and blow moderately hard. Lift the float and that will stop the flow of air. That is a bench test. You don't say where the fuel is leaking from. It's one of two places. Through the overflow vent (under the little silver plate held in by the inlet pipe) or through a gasket. Clean/clear the needle opening with a cotton wool bud

[UHR850]

It leaks on the gadget, so the reason must be the fuel will not be stopped when the float will be high enough

[Peter Laidler]

CORRECT. The fuel pressure is quite low. I suspect and agree that the needle is not stopping the fuel flow for some reason. So remove and clean the needle and housing as described. I fear that the fuel is leaking via the small vent, hidden underneath the strip of foil - beneath the intake tube. But you've solved the problem.

Ignore fuel leaks like the plague - especially when they're this close to the exhaust!

Can I add something else too? Make sure that when you remove the 3x float chamber screws, you account for them, physically. Or stuff an old sheet down the back of the engine before you start. If, as happened to me, one of the screws drops through into the remote housing itg can - and did - anyway......

[UHR850]

But why now, it did work oke last summer and just of a sudden not any more.

[Spider]

Check the fuel pressure too. Needs to be 2.5 - 3.5 PSI.

[Peter Laidler]

We have a phrase in England that I first heard in Bandiana (Australia). It's used when there is no other explanations available. Well used in engineering circles and probably used by one or two forumers in the past. It says '......shit happens'

It happened to me a couple of summers ago. Insufficient fuel getting through. I strip carb fuel system down and use Mr Henry Hoover to suck out the shite. Worked very well. So well, that Mr Henry was spluttering. Until I looked around and saw that he was on fire!

[UHR850]

shit happens'

[Spider]

We have a phrase in England that I first heard in Bandiana (Australia). It's used when there is no other explanations available. Well used in engineering circles and probably used by one or two forumers in the past. It says '......shit happens'

It happened to me a couple of summers ago. Insufficient fuel getting through. I strip carb fuel system down and use Mr Henry Hoover to suck out the shite. Worked very well. So well, that Mr Henry was spluttering. Until I looked around and saw that he was on fire!

Take it as a sign,,,,,,

A sign you needed a new Auto-suck.

[UHR850]

I found the problem, where is this small hole for what does it do bisides overfloting ?

Kees.

[Ronnie]

It is an air break, stops fuel siphoning out the fuel tanks.

[UHR850]

Is it possible to close it without problems, The float has no influence on this, it will continue to overflow on it.

Kees

[Ronnie]

NO You must have a float level/ needle v/v or fuel pressure problem for fuel to be running out in the first place.

[Peter Laidler]

Nope....., that is a vent hole to allow the float to raise and lower without undue influence of trapped air. If the float were punctured in some way, and was sitting lower in the bowl that it should be, slightly BEFORE it could operate the needle valve, the fuel would vent through this hole too.