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MG Midget and Sprite Technical - Crystals in float chamber?

Taken out a lot of gunk (Rust etc etc) from the float chamber, cleaned and checked all other parts are moving freely, replaced onto engine, starts up rides fine then dies... or only goes with choke on or on full even after 15mins warm up around town at steady speeds..

All pointers lead to blocked main jet, so I strip and clean (AGAIN) and after more digging and dirt removal, I see right at the point where the tube connector joins the float the chamber itself..a brown crystal-like substance that wont shift easily...if at all

What is it, and how do I get rid of it? Ive been poking at it with small headed screwdrivers.

The Carbs off and out of the car.... Ive fitted a fuel filter (in case it was a rusty tank, there are no air leaks or fuel leaks, and the pump is working fine and new style air filter (pancake rather than frying pan). and Im checking to see if I need to change needles, but this problem was occurring before I did any of this (hense the multiple strip and cleans...)

Any ideas?
Ross Adams

Hi Ross

Sounds like you need to clean out your carburettor completely. The substance you describe sounds like it is a constituant of fuel that has broken down into heavy elements from being stood a long time. Fuel like this takes a lot of clearing and stripping down is the best policy.

I thought you were describing an SU carburretor but then you mentioned main jet? If you have an SU then they only have 1 jet so it regulates fuel for all speeds however irrespective of that your problem does require that the fuel system is proved right to begin with.
Bob Turbo Midget England

What product or substance should I use to break this down with?
Ross Adams

It sound similar to the residue others are finding after using ethanol blended petrol. Try some standard carb cleaner and then use a product like Sta-Bil to help prevent and corrosion caused by the alcohol.
B Young

Welcome to my world...i feel for you

Ive been using carb cleaner and acetone. Acetone is the active ingrediant in brake and carb cleaner...thats my understanding. Along with pipe cleaner brushes... I go to a carft store that focases.heavly on school supplies like hobby lobby cause they have them in a lot of differant gauge sizes.

Just a hint...look inside the lid of the float chamber, i had that white powdery crystal stuff packed in those passage ways also.



Job done.. thankyou one & all, noted on the 'Ethanol' problem... I'll keep tabs on the situation!
Ross Adams

Sounds pretty much like the problem I have with my 1500 (UK spec, double SU carbs).

Due to a new addition to the family the midget stood in the garage most of last year so the petrol is probably mostly two years old (and 5% ethanol).

I've already checked air leaks, all ignition parts, fuel filter and pump. I've been working my way up to the carbs hoping to find something obvious and less messy than taking the carbs apart. Well well, always nice to share misery ;)

E Lindgren

This thread was discussed between 08/10/2011 and 10/10/2011

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