Fuel overflowing from Carbs on first fill - help please

[rjahunter]

Hi all.

Just put petrol in the tank for the first time tonight, and discovered the fuel pump wires were the wrong way round ! Changed them and the pump sprang into life. Watched with a tear in my eye as the fuel filter under the bonnet filled up for the first time in twenty years.............and then switched off quickly as fuel began pouring out of the overflow pipe from the carburettors !

Any quick thoughts ? I THINK I've got my carb plumbing all the right way round but if anyone wants to tell me the eejit's guide to which pipes go on to which nozzles on the carbs I'll give it another check, although I thought I had it right.

Bit of a setback, but onwards and upwards.

[fastblatt]

Overflow pipe?

[rjahunter]

Overflow pipe?

These ones:http://www.rimmerbros.co.uk/ProductI...GRID005207.gif

[Mark S]

Carbs off - Single nut in centre of pedestal and you should get away without having to remove the cables, float chamber bottoms off, needle valves out and to be freed off (preferred) or replaced (poorer quality than original).

[rjahunter]

That sounds simpler than I suspect it is ! I'll have a look and see what I can do - thanks for the advice.

[Mark S]

Not quite that simple but not too onerous for the uninitiated either.
You will need to remove the breather pipes, air filter box (there is a little pipe underneath that you will need to release if its still there), vacuum advance pipe (and the little screw fitting on the carb). You will need a thin walled socket to undo the pedestal nut then the whole assembly will lift off. There MAY be enough slack in the cables to lift the whole lot off and turn it upside down.
Be careful not to drop anything into the manifold! I stuff old carrier bags in such holes just in case.
Undo the float chamber screws (remember which screw goes where) and tease the bottom off. Unscrew and remove the needle valve being careful not to bend the float assembly. Squirt with penetrating oil and work the tit until it moves in and out very freely. Blow into the bottom of the needle valve and make sure it opens and closes off when pressed in.
Remove the plastic cap from the bottom of the float chamber while its off and replace the O ring as it will probably be perished!
Check the floats for holes (no petrol inside) Refit the needle valve and float chamber bottom using a new gasket.
Repeat for the other carb.
Remove the bags and refit the pedestal using a new big O ring.
Make sure that both carb pistons move freely, lift up and drop smoothly, remove and clean if they don't.
Remove the diaphragm covers and check they are not split or perished, and top up with oil.
Refit the filter box and other bits you have removed.
Check that the choke and throttle mechanisms operate.
There are no doubt some bits I have forgotten but when you get going, the job is common sense really.
Good luck!
Mark.

[rjahunter]

Now that really is what I call helpful instructions ! Thanks a lot Mark. The carbs are a newly reconditioned set and all gaskets etc will be new, but I'll go through this at the weekend and see what's up with the needle valves particularly. Richard

[Ian Durrant]

I have only one thing to add to Marks excellent synopsis, check the float height! mine was out by 2mm and it fixed all sorts of flat spots and other issues when I corrected it.

[fastblatt]

Ah...... That overflow pipe...... I have had this same problem myself recently, It doesnt do it all the time and when it does it stops after a while but here's the thing, I have changed the valve twice and it's still overflowing. I have also set the float height and checked that it is not leaking. I'm now at abit of a loss as to what to do next.

[GDPR]

Float fitted upside-down?

[fastblatt]

Now...... I had considered this but the witness mark on the paddle that closes the valve indicates it is correct. Hmmmm. Also thinking about it, I don't know if the petrol is coming out of the overflow. It just seems to be running down the side of the carb (bowl gasket seems fine).

[the tim]

what does angus think it is,i though he was helping you,

[rjahunter]

What valve ?!

I hate to be boring in terms of solutions, but remember my carbs are new refurbs as opposed to original - on the advice of the guys who built the engine, we removed each overflow pipe in turn and proved only the passenger side carb was overflowing, whereupon we GENTLY tapped the float chamber with a HAMMER () and ten seconds later the pump pressured up and the leak stopped. What a relief not to have to do the whole carb removal thing. Still not got the car started mind you - see separate post !

Richard

[V Mad]

What valve ?!

I hate to be boring in terms of solutions, but remember my carbs are new refurbs as opposed to original - on the advice of the guys who built the engine, we removed each overflow pipe in turn and proved only the passenger side carb was overflowing, whereupon we GENTLY tapped the float chamber with a HAMMER () and ten seconds later the pump pressured up and the leak stopped. What a relief not to have to do the whole carb removal thing. Still not got the car started mind you - see separate post !
Richard

The same happened to me. I rebuilt a set of Stroms for a friend, and when fitted one overflowed (flooded). We gave it a tap/shake and then all was well; and still working ok.