K11 Micra. Engine is flooding every morning and it is a swine to get started. Seems it can't handle a cold engine rich mix. Will replacing the spark plugs fix this (they have been in for 50k)? Is replacing the plugs a newbie job or should I get a garage to work on it?

Only a novice, but try complete carb strip down & clean all jets etc.

Have previously experienced loads of deposits in most of the carb jets and float chamber causing this usue. (Low mileage on the clock of the carb I once worked on, but it had been in storage for years) and a couple of jets were completely blocked, but apparently the main flooding was due to the large amount of deposits immediately under the float needle, in the actual needle chamber and underneath the chamber housing in the carb.

Remove float and needle carefully and check their is no calcification or dirt deposits on either (often caused by condensates and particulates in the fuel itself) and no holes in the float. If their are deposits then lightly clean, if holes in float then replace. (I had to use a contact pen to clean my float, as calcification was severe causing aditional weight to the float. This means higher fuel levels in float chamber to lift float to cut off point, causing flooding. Rinse and soak cleaned items in clean fuel.)

Check needle chamber is clean. Remove any debris from chamber using petrol soaked quality cotton buds. Remove entire chamber assembly and underneath the base of assembly is a tiny fuel filter at the underside of the assembly and bottom of the carb chamber itself.

Remove fuel filter very gently to keep intact and gently rince in a cup of clean fuel. (Do not jet with cleaner as mesh may perforate with the force.) Gently brush grit from filter internally and externally with soft small paint brush and leave to soak in new clean fuel for 10 mins. Meanwhile, clean base of needle assembly cavity in carb for any large dirt heald back by the filter.

The dirt and deposits acumilated in ours was astonishing!

Continuously clean assembly chamber housing with quality dampened cotton buds. Once clean, jet through with Carb cleaner or similar, to rid chamber and chamber screw thread of any remaining grit. Also jet needle asembly thread to rid it of grit before resiting in carb.

Test needle in needle chamber asembly to ensure it seats fully with no needle snaging in chamber and seats comfortably at full seating.

The large quantity of grit in mine prevented full fuel flow, but also correct needle seating, but the addition of blocked filter and jets caused the fuel pump to over compensate; assuming fuel starvation, but causing considerable fuel flooding and in turn coked sparked plugs.

Once all are cleaned, and needle movement in camber is smooth, replace filter, then needle assembly into carb and tighten to carb. Replace cleaned float and needle, into needle chamber. Float and needle should have bounce when lightly pressed and released. Sticking indicates snagging in needle chamber or faulty float assembly.

Check all jets etc are replaced and reassemble carb with either new cork or modern carb gasket kit etc. Refit carb and enjoy flood free issues.

Hope this helps, It took 4 Carb strip downs for me to even realize their was a filter under the needle asembly unit, as it was not clear in the haynes. This was many moons ago, but seems to solve the issue long-term every time.

Edited by M L A Sullivan on 19/06/2020 at 01:07