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Carburettor problems

Posted: Sun Jun 04, 2023 2:24 pm
by MoggyMatilda
Took the carb off to give it a good clean & found fuel laying in the inlet manifold. I’m sure this isn’t Normal so what would be the cause of this? I believe this to be the trouble with my idling & staring etc.

Re: Carburettor problems

Posted: Sun Jun 04, 2023 4:27 pm
by philthehill
The fuel level in the float chamber could be too high causing fuel to spill out of the jet and into the manifold.
Check the height of the fuel in the float chamber using the information given in the BMC Wksp Manual, section BBB6.
Check the condition of the float needle and seating and if any doubt replace with a ethanol resistant needle and seating.
Fuel spilling from the carb float chamber will cause problems with starting and idling.

Re: Carburettor problems

Posted: Sun Jun 04, 2023 4:46 pm
by mogbob
Answer no , you're correct.
I'd look carefully at the needle valve inlet. Needle itself first , is it worn ? Evidenced by wear in the cone shaped tip. Does it have a ridge that can seen and felt with a finger tip ? Is the needle " free" to rise and fall , not hindered by dirt / dust clogging up it's operation ? Any issue in this area it's probably
easiest to renew the needle valve completely.
The float , is it sound , not holed. Can you hear petrol sloshing around inside the float. If compromised replace. You can get more expensive floats that are sold as being unsinkable. From memory they are called Stay Up floats ( I stand to be corrected ).Check the float needle height is correct and adjust if not correct ( allowing more fuel into the float chamber bowl )
These areas would be my first port of call but check out the carburettor jet set up whilst you are in there. Is the petrol jet tube from the base in good condition? Any leaks around the joints 1.exiting the float base and 2. entering the carburettor body. Examine , clean the piston and reset the needle position if required. Carry out a piston drop test ( detailed instructions on Burlen Fuels website for overhauling the carb ), If you carry out the overhaul
the immediate problem will be solved and most likely the general idling and poor starting too. A bit of lubrication on the controls , accelerator cable and joints wouldn't go amiss either. Cable route accelerator to carb correct , no sharp bends hindering operation ( put back incorrectly by a previous
owner )
Burlen Fuels or Southern Carburettors would be able to supply any parts required along with a number of other Morris Minor parts suppliers.
Good luck with it.
Bob

Re: Carburettor problems

Posted: Sun Jun 04, 2023 5:19 pm
by philthehill
These are the parts you require if the float or needle/seat are faulty:-
https://sucarb.co.uk/float-chambers-spa ... valve.html

Re: Carburettor problems

Posted: Mon Jun 05, 2023 8:07 pm
by MoggyMatilda
Thanks for the help! Got it sorted. Think the float needle was sticking aswell as the piston itself. A good strip down & a clean seemed to do the trick.

Car drives really well now & pulls nicely in every gear. So I’ll leave well alone & see how she goes on a long run some evening.

Re: Carburettor problems

Posted: Tue Jun 06, 2023 5:29 pm
by mogbob
Great result... well done Safe motoring.
Bob