Webber 32/36 Strange Fuel Leak - Help

[Guest 2B-EVO]

Hi guys,

Hope someone can help me with this - I have a standard 2.0 pinto running a 32/36 webber. Car starts and runs fine. No fuel leaks while running however when I switch off after a minute or so fuel starts to drip from the bottom accelerator pump diaphragm cover arm. I've replaced the pump diaphragm but the problem still persists. Anyone any ideas as to why it only leaks when I stop the engine?

 

Cheers

Andy

[IanS]

When engine running it is sucking air in therefore everything in the carb is below atmospheric pressure, how much below depends on where in the carb.

This sucks the petrol in.

When stopped the carb then becomes at atmospheric pressure and the petrol can leak untill the float chamber is empty.

[Bob Tucker]

The accelerator arm is the lowest point on the carb.

A leak from higher up on the carb, may well drip off the accelerator arm.

Look for a greasy yellowish stain above the arm

[Guest 2B-EVO]

The only stain is on the inlet manifold, however having had a closer look it may be that the fuel is leaking out where the butterfly spindle comes through the body of the carb and therefore does anyone think it may be that the float height needs to be re-set or possibly a faulty needle valve is allowing the carb to flood after the engine is stopped?

I think i've answerd my own question here .

I'll report back.

Thanks

Andy

[Bob Tucker]

I suspect float height, so start with that.

 

Whatever pump (mechanical or electrical ) you are using will stop as

soon as you tun off the engine, so a leaking needle valve shouldnt cause it,

but I guess there could be residual pressure in the fuel pipe.

A full refurb of the carb should fix it.

I dont know if there is an O ring for the spindle?

[PaulF2B]

If you do need to strip the carb' or just see the internals, check out this topic in our forum, there's a nice link there:

 

"Rebuilding A Weber 32/36 Dgav Carb"

 

http://www.rhocar.org/index.php?showtopic=36620&hl=%2Bweber+%2Bcarb+%2Bsite

 

 

 

[Guest 2B-EVO]

Hi all - quick update on the fuel leak. Thanks for the link Paul - I had already seen that guide but your link provided a quick ref when servicing the carb today. Anyway I traced the leak to a seized ball bearing in the needle valve allowing the carb to slowly flood after the engine was off due to the residual fuel pressure in the fuel line. While I had the top off the carb I noticed that the hole that is linked to the power valve diaphragm is blocked by what looks to be a crushed brass insert. The car funs fine but does feel a little flat until the second butterfly opens. Does anyone think this could be the source of the slight lack of power?

 

Thanks Andy

[Guest 2b cruising]

Yes. If the accelerator pump is not pumping fuel down the Venturi, this will cause a flat spot.

Edited August 15, 2015 by 2b cruising