21 replies to this topic

[dowdow]

Hi there.I am new here! I have a mini and the carb..su carb is leaking petrol from around the gasket of the float chamber..the gasket is new..the float is good,not punctured etc and the level is good too..even the valve which stops fuel from entering the chaber is new..it starts ok ec..after about half a in a minute I see petrol leaking from around the gasket..a slight leak..the mini was stood for a while and has new petrol pump..any help please?! thanks

[robminibcy]

That would be the valve not sealing for some reason.take it out and give it a clean to make sure there's no grit stoping it from closing properly

[dean]

Very strange. It's always something that you have over looked are something you have touched. Double check for blocks

A mate had the same problem fine when the revs were above 1100rpm. But below that it started to mess about.

Think he just changed the float bowl to save any messing around with a spare he had.

What type of carb its it hs, or hiff

[dean]

Also heard that the petrol can wear the seat where the valve sits against

[dowdow]

but I tought that if the valve is not seating good..the fuel level would be high when I remove the float cover..but the level is good.ie about 2 cm from the bottom of the flaot chamber...

[dowdow]

sorry it an hs carb...tnx

[dean]

We found that too you blow down and it seems to seal tight.

If you have a spare float bowl and nothing else works , swap it over

[dowdow]

i changed the float bowl with a second hand one I had laying around.becouse the one I had had a hole..it has the fixed type float..so I cant even adjusting it..could it be there is s small crack on the float cover? I even put 2 gaskets ! its gettting me crazy!

[wile e coyote]

Just an idiot question for you - you say it's got a new fuel pump - std mechanical or electric???? If electric could be pumping fuel in at far too high a pressure - with all due respect to those that shop for go faster toys(and that includes me) temptation can get in the way... the std facet one is fine at about 2- 3psi from memory (don't quote me on that) but any high performance / fast road etc pump run without a pressure regulator can overwhelm - causing leaks.....

[Ivor Badger]

Check the fuel pump pressure, but probably correct. Replace the plastic float and float needle valve. The problem is probably the float as changing the nv doesn't often solve the problem. Never actually seen a fault in the float, but I suspect the top goes soft where it sits on the nv.

[carbon]

If car has been standing for a while its possible there may be some dirt in the fuel line. Just takes a small lump on the float valve to cause a leak, been there. The fix for this is an in-line petrol filter positioned just before the float chamber, the cheap disposable type works fine just make sure the tubing fits well and use proper hose clamps of correct size.

[dowdow]

hi..the pump is mechanical type..its not the same design but I think the pressure is the same..I will put a filter before the carb as someone said,..yes the petrol is a little bit old...

[KernowCooper]

Are you sure its the gasket? I have seen the rubber fuel line where it pushes on the inlet to the float cover brass inlet pipe leak and the fuel will run around in a 360 arc and look like a gasket leak

[dowdow]

hmmm sound interesting kernowcooper..! I will start the engine and look very closely to see from where is the leak....tnx mate

[dklawson]

Along the same lines, old fuel lines have trouble sealing once disturbed and they can shed crumbs of deteriorating rubber from their inner wall. If the hoses are old, fit a fuel filter between the pump and carbs and replace all the flexible lines from the pump to the carbs.

The difference between high and low fuel in the float bowl is difficult to judge when you remove the lid from an HS carb. Remember that a large portion of that fuel (that will appear low) is displaced upward when the float is in the bowl.

If the float is the all plastic type without the metal arm, you may want to adjust the number of fiber washers between the needle valve and the float bowl lid. An extra washer will effectively lower the fuel in the float bowl by quite a bit.

There have also been anecdotal reports of new float valves not sealing properly. (Before going further, if you have installed Grose Jets with the ball bearings... remove them and fit Viton tipped traditional float valves before spending any more time troubleshooting). If you have a float valve with metal on metal sealing surfaces, you can try lapping the two contacting surfaces together. People on this board have used toothpaste for this purpose in the past. If that is not something you want to try, buy the Viton tipped float valve I mentioned earlier. The Vition tipped valves seal very will for long periods of time when other valves have problems.