Flooding

[LordAnthony]

Hello,

My fuel pump won't stop ticking and it floods the engine when idling.
I've taken the carb to pieces and have cleaned it all up and fitted new gaskets etc. I've taken the lid off the chamber and have attempted to blow through the valve and couldn't do it so I assume that the float needle's ok. Could the problem be the float itself? Any other suggestions?

[Neil MG]

If it has a brass float then they often fill with fuel due to tiny cracks or pinholes. Easy to tell, just give it a shake. Mine was like that when I got the car. I put in boiling water and marked where the bubbles came out. Then I dried it out for several days on the Rayburn before soldering. Easy to get a new float too!

May also be a leaking or incorrectly adjusted plastic float if you have a later carb.

[Neil MG]

Oh, almost forgot, yes my kitchen did smell of petrol for a couple of weeks....

[LordAnthony]

It's a later one with a plastic float. I checked the gap with a drill bit and it was fine.

[bmcecosse]

The plastic floats bare basically non-adjustable anyway - the little float valve will be ridged and leaking petrol through - you need a new one. Yes - it may hold air when you hold it shut with a finger - but can still leak petrol when in use.

[LordAnthony]

Right you are. New one on its way from ESM.
Thanks for your help.

[mike.perry]

If it still does not work then I expect that you will tell us.

[LordAnthony]

Funny you should say that, I fitted the new float needle and the brass barrel thing today and it still flooded. I guess it must be a leaky float or it may need adjusting even though the gap appears to be correct and there's no petrol swishing around inside the float. It only clicks once every 5 to 10 seconds but I don't think it should click at all with the engine off.

[Neil MG]

Does it still leak? I have fitted one of the electronic SU pumps that still clicks without the engine running.

[LordAnthony]

I've got one of those pumps with the blue cap too.

I didn't realise they clicked even when full. I'll stick my finger over the end to make sure.

Perhaps the flooding this time round was due to my messing around with the mixture.

[mike.perry]

If the ignition is off then the fuel pump should not tick. If it does then check that it is wired into the ignition fuse.
Have you checked where the petrol is leaking from? If it is from the float chamber or carb venturi then it is a float or valve problem, if it is under the carb then it is a seal.
The mixture setting will not affect the flooding unless the mixture screw or jet assembly are loose

[bmcecosse]

Ahh -are you just assuming it's flooding because you hear the odd click? Do you actually SEE the fuel flooding over the jet bridge if you remove the carb bell with needle? An odd click is quite normal - BUT - you should NOT in any case leave the Ignition on when the engine is not running - it seriously overheats the coil........

[LordAnthony]

I should explain a bit better. I could smell petrol the other day and went to pull over, as I slowed up the car stalled. I opened the bonnet to see a puddle of petrol: a big leak.
I removed the chamber lid, cleaned up the valve as best I could and went on my way, all seemed fine for the remaining mile. There was no sign of any rust or gunk in the bottom of the chamber. One thing I did notice was that the needle valve was in the bottom of the chamber. I thought at the time that it had fallen out as the float dropped when I lifted the lid, but I wonder now if it had come out when I was driving along? The other thing I noticed is that the pump was still ticking even when it had filled up, which made me assume this was the cause of the flooding.

I fitted the new valve the next day and the ticking did become less frequent with the engine off (I did limit the time spent in this state without the engine running) but it was still there - no more than 10 seconds apart.

I went for a drive, all seemed fine but it was running fast, so I started adjusting the mixture only to have the car stall and the petrol come out underneath the piston as I was lifting it (the lifting pin is stuck so I had to remove the air filter hence I could see it coming out).

Over the last few weeks, up until this point, the car has been ok until it has been driven for a few minutes by which time it threatens to stall when idling, but never bad enough to cause concern. The exhaust is quite sooty too so I'd say it has been running rich.

I will check to see that I haven't loosened the screw above the mix screw and also that the pump still ticks with my finger covering the end of the fuel pipe. Does this sound reasonable or am I barking up the wrong tree?

[bmcecosse]

Sounds very reasonable - a new valve should work perfectly - so indeed better check that float......

[Kevin]

I've got one of those pumps with the blue cap too.

Unfortunately that is not the proper SU pump but one of the aftermarket pumps from germany that are well know for giving all sorts of problems, the blue cap is the giveaway, I hope your problem is not caused by the pump.

[LordAnthony]

All seems fine now - I gave it another clean adjusted the timing and mixture and it's running better than ever.
Sadly the car came with the blue pump, but it seems to be working ok.
Thanks for your help.