Massive Over-fuelling

Mini Technical Sections Problems, Questions and Technical
1

Got a standard 998cc 1990 mini city. SU HS4 Carb (with the mixture nut on the bottom)

Drive the car from Taunton to Plymouth (70 miles ish) on friday and was fine, never missed a beat.
Drove the car yesterday and felt a bit lumpy, kept cutting out when I stopped.
Drove it today and it’s ridiculous!
Had bit of a fiddle with the mixture screw, (in or up is leaner, out or down is richer?)
Didn’t notice it before, but might have been from me fiddling with it but the fuel is literally gushing out of the overflow pipe!
It did stink before to the point where I had to have all the windows open whilst I was driving.

The thing is, I can’t work out what it was that could have caused it to mess up in the first place.

Is there any way I can get the mixture roughly correct so that I can drive back to Taunton and get my colortune?
Need to go today really

Help greatly appreciated!

2

**Luke, Please do not use special charaters to get around the swear filter.

It’s there for a reason**

It sounds more like the valve in the floatbowl is not closing and is allowing fuel to be continuously pumped in. Might be worth pulling the floatbowl lid off and seeing if it’s stuck. Mind the gasket though.

3

my apologies, was a bit frustrated!
Will try that now and see what’s what. Cheers.
What should I do regarding setting the mixture as I have messed around with it now…fool!

4

if you do a google search i’m sure there is a “base” setting for them. I’ll have a flick through my haynes and see what its says.

5

Thanks for your help, the float seems to be pushing the valve up and down freely. have re-connected everything and it actually runs without stalling now.
Maybe the valve loosened itself as i took the lid off.
waqnt to check the mixture though as i wound it up (lean) about 2 turns but don’t expect it to be correct!

6

Just checked haynes, it says after you have do a refurb on the car to set the jet height so the top of the jet it flush with the venturi bridge. Basically you will need to take off the air filter, lift up the piston and make sure the top of the Jet sit’s flush. This should be enough to get you home although the fuel mixture should be set properly sooner rather than later.

7

am I going to have to remove the dash pot to get to the piston?

8

sounds like the float valve got dirt in it,

if it keeps happening add a fuel filter before the carb.

9

nope, if you look down the inlet you should be able to see it, might be a bit awkward but should be possible.

10

**topic sub-title amended. Luke, doesn’t matter how frustrated you are, please think before you post. This is a family forum.**

11

OK, got it, seems to be running ok now, i’ll take it for a quick spin and see if it’s driveable!
Thanks for all your help!

12

it’s doing it again! will take the lid off and have a look again, maybe there’s something still in there.
There’s a puddle under the car

Pouring was the word I was looking for! Again, I apologise.

13

the float and valve seems to be moving freely when it’s not in the car.
the float chamber is completedly brimmed with fuel so it seems there is a problem with the valve but if i blow down the pipe where the fuel goes in the valve stops the air.
looks clear inside the chamber too?

14

is it possible to alter the height of the float? Also check to see if there are any holes or damage to the float, if it’s letting in fuel then it won’t float.

15

Float is fully intact. can’t alter the height of the float no.
when I blow into the pipe the float only needs to move slightly to stop the air coming through.
how can I remove the float?
the pin that holds it is really stiff, don’t want to damage the float!
the thing i can’t fathom is why it works when its not in the car.

16

When you have it in your hand then you may be able to move it more than the fuel level can. You should be able to push the pin out with something just enought to grab it with a pair of pliers.

17

i had that problem for weeks when i had a 998 (i got a hiff44 on a 1400 now). i totally recommend putting a filter in anyway regardless. i even when to the extent of blasting the fuel tank out at work. still can’t beleive how much crap come out. anyway. what i did to the float chamber was got some more gaskets for it and took it apart and found load of crap in the float valve and sitting in the bottom of the float chamber and use brake cleaner to clean it all out with a small detailing paint brush. lubed up the valve with wd40 and worked it as it should normally do when back together holding it upright and flicking the float to open and close it and then put it back together. good as new worked a treat for ages. then i moved on to hiff44’s

18

took the chamber off, there was a fair bit of scum in the bottom, haven’t got any brake fluid so cleaned it out with a bit of wd40.
will re-attach and see what happens…

19

grrrr…took the chamber off…fail! should have taken the whole carb off; I took the hose out of the bottom of the float chamber and lost the little copper washer that holds the pipe in
I’ve tried re-attaching it but it wont stay in.
what a *male chicken* up!
any way of attaching it without the washer?
can you buy them anywhere!?