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MG MGB Technical - Petrol gushing from 'breather'

Hi; My 1978 MGB GT UK spec is pouring petrol from one or both of the two metal pipes that are clipped to the engine block very close to the manifold - I thought those pipes were breather pipes for the carbs but I'm not very mechanically minded!

What's the problem and what's the fix?

Chris
Chris Thompson

It sounds like your float or float needles are sticking! The fix is to remove the float and clean out the needle and seat so that they close properly! Without them closing properly, the fuel pump will continue to push fuel out!
Jeff
Jeff Schlemmer

Or a punctured float. Though if the problem comes and goes, then it's more than likely a sticking problem.

You could try tapping the carb with a screwdriver handle to see if that unsticks something. Only as a temporary fix, of course.

The two pipes aren't breathers, they're overflow pipes, such that when the float bowls overflow, as in your case, they discharge onto the ground and not onto the hot exhauust manifold. But don't be tempted to block them.

'78 UK spec? Would that be dual SU HIF4s? Not so easy/convenient to access the float and needle to check as the HS4.

Bood luck.


Derek Nicholson

Chris

I recently had the same problem with my MG and following advice from here changed the floats and needles its a quick inexpensive job which sorted the problem.

John
John

It's a long time since I used this bulletin board but it's nice to see that people are as quick to respond and as helpful as ever. Thanks.

Chris
Chris Thompson

Chris,

As well as the previous advice, I would fit an in-line fuel filter. The plastic type with the paper element.
Small particles from the fuel tank can jam the float needle valves.

Mick
Mick Anderson

This thread was discussed between 20/08/2006 and 21/08/2006

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