Leaking float chamber

Post by **splitscreen** » Sun Oct 12, 2003 5:40 pm

The fuel pump on my '63 saloon wont cut out, shooting fuel out of the carb float chamber/inlet hose. I've checked the float and tried on two other lids from the same type of carb and replaced the float needle, seating and lid gasket but all to know avail.
Any advice would be much appreciated.
Thanks, Paul

Post by **Gareth** » Sun Oct 12, 2003 5:58 pm

Your float chamber lid ought to have a small baffle covering the overflow, just underneath the fuel hose - make sure this is in place.

Also, check the tightness of all the hoses.

You have tried some other lids so it shouldn't be the lid/float assembly. I presume you just fitted a "known to be good" lid and float assembly - the other way is fraught with problems, and is very difficult.

If all is well here, then it could indicate that the pump is pumping too hard. Have you had the pump replaced? Have you had the car long?

Post by **rayofleamington** » Sun Oct 12, 2003 6:16 pm

The petrol pump is designed to run until the car shuts off completely. When th carb is shut of (full) pressure builds up and this stops the pump from carrying on.

Did this happen all of a sudden?

the carb float chamber/inlet hose

Can you see exactly where the fuel is coming from??
There is an overflow from the carb, close to the inlet hose. If fuel is coming out of your carb, then it isn't shutting off completely. The bits you have been looking at are the right bits - to check the needle is sealing, you can press it into the lid lightly with your finger and blow down the inlet to see if it seals (clen the petrol off before blowing down it !!!)
It could be that the hose isn't sealing well to the carb - is the inner end of the hose in good conditions with no gouges scratches or chunks missing? Also is the hose clip in good working order and does it close up small enough to hold the hse VERY tight on the card. Also is it the right size - bigger jubilee clips might close down to clamp the pipe but if they started life as a bigger clip, they will look D shaped and they won't work properly.
If you have the round wire spring hose clamp - is the pipe soft enough to allow the clamp to work? If the hose has gone really hard it may not work well enough.

Post by **splitscreen** » Sun Oct 12, 2003 7:20 pm

Thanks for the advice Gareth and Ray. The inlet hose is near new and when the wire clip is tightened it wont pull off. I've had the car nearly two years and it has been fine - just notice last week that the pump wasn't cutting out. I've checked the needle is sealing by blowing through the pipe and tried a new needle and seat.The baffle over the overflow hole is in place.
Paul

Post by **Willie** » Sun Oct 12, 2003 9:35 pm

This should be simple...if petrol is pumping out of the
float chamber overflow then the needle valve is faulty
or the float is not rising up to operate it. Petrol cannot
emerge from the float chamber gasket unless the
level is too high..again caused by an inoperative valve.
Let us know what you find.

Post by **Benjy** » Mon Oct 13, 2003 10:29 am

If the pump doesn't stop pumping, is there enough pressure to push the needle back down and hence flood the chamber? Is it worth placing your thumb over the fuel pipe to see if the pump stops?

Just a thought.

Ben

Post by **lowedb** » Mon Oct 13, 2003 1:09 pm

I had a 'bike that would do something similar, every so often. Worse bit was it spilled onto the hot engine. Never quite managed an 'event' though.

Took me ages to find it, but flakes of paint from the filler neck were sitting on the valve seat and holding it slightly open. The in tank filter had been removed, so I fitted an inline filter that fixed it instantly.

I guess your problem could be particles of rust, bits from a failing pump diaghram, or maybe even dirt in the fuel. There should be a filter in the fuel pump, so check this too.

Morris Minor Owners Club

Leaking float chamber

Leaking float chamber

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