Over fuelling when going down hill?
Turbo Mini Forums

The mini has developed a strange problem of flooding/sooting up. However this seems to only take place when decending very steep hills for a long duration eg Mountains!

I was out at the weekend working on a 120 mile Mini navigational rally with the wife and the kids in the new turbo. All was well - the Mini recently been set up on the RR so assume (never assume!) the fuelling is OK.

Ok so picture this! Your heading down the side of the Mountain for about 3 miles, and at the bottom theres a Ford (watersplash not escort) so you slow down gently cross the ford and put your foot down to climb the very steep otherside when!! The mini dies - blocking the road with the back wheels in the river! Kids getting excited yeah! Ok you got the picture.

It seems the carb starts to flood on very long durations when engine braking, also the mini has started smoking blue smoke when accelerating after the throttle been shut during engine braking (high vacuum on the boost gauge)?

I have my theories, and have researched TM for similiar... But please can you post any suggestions? Sure wife and kids would be pleased!!

Cheers

Deano

Hi,
The blue smoke could well be down to the over fuelling contaminating the oil.
As for the over fuelling, could be any number of things, wrong needle profile, float height, fuel pressure incorrect, restricted fuel return among others ..
Cheers,
Gavin :)

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Hi Bat
I guess its the elimanation game! Using an 8mm Copper Fuel return. Fuel pressure was set at idle at about 4 psi, so I guess it may be worth overhauling the carb as it was still sealed when I acquired it!

the turbos goosed! dean ++++++

check fuel pressure to the carb should be 3.5 to 4 psi above boost pressure

start from there

Oh no Benross!! Time to get that bigger Motorcycle and drive the Mini into the sea!

Ok mate will pipe in a fuel pressure gauge so I can monitor the fuel pressure. The one I loan from work is a little on the large side - not good for when driving etc.

Hi,
I would definately change the oil before condeming the turbo. Bud 666 had the same a couple of weeks ago.
Yes go carb rebuild, they wear a flat on one side of the needle where it rubs on the side of the jet, buggers up the fuelling a treat, even on a Reliant Robin.
Please, don't ask how I know that!
Cheers,
Gavin :)

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do a compression check as well dean to see how fit the engine is

do all the usualls you know the score!

whats left will be staring you in the face

Anyway dean when are you coming through for a Bast in my Snail ???

Cheers for that, going start the trouble shooting tonight with a compression test. Fuel pressure gauge on order, Oil and filter to be changed. The engines only donw about 1000 miles since re - ringed - fingers crossed.

Benross Easter mate I got some time off so I will bob over on the roadroacket!

It could just be a bit of oil going down your valve guides due to the high vacuum and pointing downhill.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Good evening TM
Well I got stuck in tonight and pulled off the intet manifold to discover 3&4 inlet port full of oil!
The turbo charger appears to be clean as all the pipes from the intercooler and the compressor snail again bone dry.

I did think about the Theory of vacuum in the inlet pulling oil down from the Turbo seals. however! After some thought myself, there would be no vacuum in the Turbo, as the Dump valve would be open to atmosphere so the compressor circuit would be that of atmosphere

Compression test on all 4 cylinders gave an average reading of about 12 Bar (165 Psi ish)

The Factory did a brilliant job of sealing the SUs so nobody can service them didnt they! I have removed the float chamber and supringsly considering the carb is 16+ Years old its never been opened before and is very clean. The needle valve is working OK, but I am going to check the float level. Its not straight forward taking out the float as its got tamper proof screw.

So my theory now is the Cylinder head valve guides/seals, which I will remove tomorrow. If it is the head, then I wont be happy! As it was recond 2 years ago, with new bronze guides and valves.

Will keep you posted and thanks for the help.

Cheers

Deano

Hi,
I would say it was the head if your induction pipework is dry. Unless you have the engine breathers plumbed into te carb?
Cheers,
Gavin :)

VEMs Authorised Installer / Re-seller. K head kits now available!

WB/EGT gauges. Click here for customers write-up

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sound thinking dean. but ........make sure you have plumbed the breathers in to atmosphere

fit new guids from minispares and seals

i can drift them out and press the new ones in & ream them if you wish ?

pm me buddy
done in the day

Edited by BENROSS on 13th Mar, 2007.