19 replies to this topic

[MIGLIACARS]

hello
had this mini a while now 85 b reg 998cc totally standard.
its been fine.
took it for the mot and its started leaking fuel from the overflow, so it failed.
took it home.
took off the top of the float chamber, its spotless in there, so to is the cap.
changed the cap for 3 spares i had, its still doing it, there is nothing stopping the float coming up and when the float is at the top it cannot be blown through.
went inside and had a think, came out its fine, left it ticking over for 30 mins still fine, went for a drive still fine, took it back to the garage it starts leaking.
fail they must think im an idiot.
brought it home fine.
its mechanical fuel pump which is new.

the needle is clean and move freely it looks brand new.
ive emptied the fuel pot to make sure theres no bits in there it was spotless.

why is it doing this.
also why have some pots got overflows and some have not

[thebullet]

Is the needle sitting right?

[Bungle]

my guess it's a stuck needle valve

[racingbob]

take it to another garage it might be OK

[tiger99]

Sticking needle valves are one of those things which just happen, even if they look in good condition. Too much or too little side clearance may both make them jam. But dirt or wear on the seating is another possibility, and the angular movement of the float may cause sufficient side load to make it stick if the float operating arm and needle contact surface is not in perfect condition. The float pivot on its spindle can also jam.

I would try a new needle valve assembly, and a new float.

[davej]

I`ve been having the same problem recently, I tried two new needle valves and it was still doing it whenever it felt like it. In the end I bought a new cap assembly from minispares (part number: AUE266) it came built up with the float so I just swapped it over. At the moment everything is fine.

[MIGLIACARS]

but ive tried 3 different caps now each with its own float surely they cannot all be fu ked

can i just put a cap on there with no overflow?????????

[Bungle]

maybe it's muck in the fuel making them stick

have you got a fuel filter ?

[MIGLIACARS]

yes that could be it no there s no filter yet!!!!!!!!!!!!!!

[Ethel]

Is the float bowl level? A filter will help by damping the line pressure, if nothing else.

[MIGLIACARS]

its quite level but does move a bit. i know you can tighten that bolt on the other side but i have 3 spare carbs and they all move a bit so thought it was normal.

[MIGLIACARS]

ok, went to the mini today it started fine, i left it ticking over until warm and drove it around even past the test station to fool her, came home everything fine.
took off the chamber top and sucked out the fuel to see a very clean pot took the cap apart and cleaned every bit even though is was immaculate, took needle out its perfect, reassembled it and tested it by raising the float and blowing, it works fine.
i then levelled the chamber and tightened the nut.
then i removed the pipe from the pump and replaced it and added a filter.
reassembled it and off i went, braking heavily to see if i could make it do it and it didnt brought her home and left her ticking over for ten more mins still fine.
ill tack it back to the test centre wens see if it happens again.

what more can i do.
is it only me who gets these issues, mini were made to test me, im sure.

could the pump be to powerfull for the float???????????

[tiger99]

I don't think it is the pump unless you have upgraded it. Both mechanical and electric pumps are driven by spring pressure on the delivery stroke, the cam or solenoid only drives the suction stroke, so the fuel pressure is limited by the spring in the pump, and all the standard bits are designed to work together.

I do think that a filter can only improve matters, by preventing dirt getting between the needle and its seat.

The other thing that may matter is the needle valve. I assume you have the later viton (hard rubber) tipped type, not plain brass. Viton does work better, and was introduced to cure a problem. There are probably few all brass ones still around.

[MIGLIACARS]

well its been fine all day so far.
im sure when she see s the ramps at the mot station things will change.

[kez_19]

mine is doing the same thing but all the time i was going to run a pipe back to the tank but is that necessary???

michael