Anyone work magic ?
Turbo Mini Forums

This is driving me nuts !! Got my car on the road again early last week with T2 Turbo and rebuilt carb.
I had been having problems with fuel starvation since last year, but after stripping the carb for an inspection and finding a piece of rubber pipe wedged inside the fuel inlet i though my problem would be solved. The carb was fully rebuilt and fitted along with the new Turbo setup.
But the problem still persists !
Flat out in 1st and 2nd running 8psi the lambda reads rich, but once the engine really gets under load in 3rd and 4th it begins to drop down into the mid/lean. I have now profiled the needle to the point that it's now like a bloody hair !! The engine runs really well and pulls like f##k for such low boost, but if i run any more boost it leans out to much.
I've tried all the usual stuff, new pump, checked regulator for faults, return isn't blocked, pump flows more than 1.5litres a minute, reulator is set at 3.5psi at idle and rises accordingly with boost, fuel and return lines are 8mm, feed to pump from tank is 10mm.
Well i'm fookin stumped
I'll i can think is there must still be a carb problem so i'm gonna try my mates {proven} carb.
Anybody else got any bright ideas ??

Phil.

WWW.TURBO-MINI.COM

You tried TD's magic T-piece trick?

Edited by evolotion on 11th May, 2005.

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

The gauze on the fuel pickup inside the tank blocked up with shite?

Tried the T-piece trick yes, made a slight difference but not much.
Gauze removed from tank.
Keep em comin guys ........

Phil.

WWW.TURBO-MINI.COM

Any of your fuel filters blocked, balance pipe, loose jubilee clip/split hose somewhere on your t-piece set up so float chamber is not sealed properly!!!

-MINI CLUBMAN 1380 TURBO-

Float level incorrect? Float full of fuel? Needle valve passing?

Fuel filter is new and not blocked, i have tried with and without the balance pipe to no avail. Hoses are new or in good condition.
Float was set when carb was rebuilt, but i still had the same problem before the carb was rebuilt anyway.
I've tried pretty much everything, but still suspect the carb ..... mmmmmmm.

Phil.

WWW.TURBO-MINI.COM

If you want to try a different carb, mine is on the shelf and probably won't be needed for another couple of months. It would cost a penny to ship (I'm in the US), but I could loan you mine.

**************************************
1967 Cooper 's' Turbo build @ www.drjing.com

As you are accelerating 1st to 2nd the dashpot oil is really working to provide a richer mixture. As you end up in higher gears the airflow has probably pushed the dashpot way up and the oil is providing less of a richening effect. The Dashpot spring may be weak or insufficient against the rush of air going by. Try another if you have one. It is an easy thing to check, and it may solve the problem

Regards
Graham

Have you tinkered with the plenum restrictor? Is it still there?

phil

i discussed this with iain at avonbar around 5 years ago
and he suggested that on some particular setups
i.e. engine cofigs he has found that this happens.

he suggested to me what they used to do on the metro challange cars was drill the float bowl needle valve orafice to 2.9 mm and that solved the problem of fuel stavation

ITS THE FLOW RATE INCREASE YOU NEED

i think! its 2.9mm check with him to be sure of this size and then seat the needle valve back in with some fine lapping paste

firstley i would try the other proven carb and see whats what???

anyone come across the above mod before??

solved my problem with daves T peice trick (magic)

Phil, I'd like to see a pressure gauge connected to the carb vent pipe (without it tee-pieced into the plenum-regulator pressure hose).
If this shows that the air pressure in the float bowl rises with boost and doesn't fall away, you can effectivly rule out the plenum, regulator, lines, etc - the fault can only be insdide the carb...

Have you removed the needle valve? There is (as i recall) a fine gauze above the threads. I'd be inclined to remove this (you're already running an EFI filter aren't you?) and try it again.

Have you checked the choke spindle seals aren't split, and the mating surfaces in the choke spindle bore are clean and smooth?

"Have you tinkered with the plenum restrictor? Is it still there? "

No this is still standard Dave.

"ITS THE FLOW RATE INCREASE YOU NEED"

Yeah that's what i figured, the pressures there just not the fuel supply.

"he suggested to me what they used to do on the metro challange cars was drill the float bowl needle valve orafice to 2.9 mm and that solved the problem of fuel stavation"

Cheers for that benross !! I'll ring Avonbar today.

"Phil, I'd like to see a pressure gauge connected to the carb vent pipe (without it tee-pieced into the plenum-regulator pressure hose).
If this shows that the air pressure in the float bowl rises with boost and doesn't fall away, you can effectivly rule out the plenum, regulator, lines, etc - the fault can only be insdide the carb... "

I will be trying this tonight, if this fails i will be romoving the gauze.

Thanks for all your help guys, really appreciated. I'll get there in the end ! :cool:

WWW.TURBO-MINI.COM

does the lean out show up on a rolling road!

always looking for them bigger bunches of bannanas

are you using a wide or narrow band ox sensor?
narrow band ones are not too accurate , have you checked it against a co tester ?

i found this with my air/fuel meter and tried it with the heater disconnected and it read ok so the exaust must have being to hot for the sensor ?

love that straight cut scream!!!
______
/___|_____
_ (@)___(@)

how did you get on phil?

Team Racing

"If you want to try a different carb, mine is on the shelf and probably won't be needed for another couple of months. It would cost a penny to ship (I'm in the US), but I could loan you mine."

That is very kind Dr. jinG thanks for the offer.

"does the lean out show up on a rolling road! "
"are you using a wide or narrow band ox sensor?
narrow band ones are not too accurate , have you checked it against a co tester ?"

The engine definately starts to lean out, i am sure the lambda is accurate as you can feel the power drop off when it moves from rich into the mid section.
I have drilled the float bowl needle valve orafice to 2.9 mm and removed the gauze, no difference ??
Didn't get time to fit the other carb so will be re-checking everything tonight, if i can't sort it then the other carbs goin on.
Cheers everybody.
Phil.

WWW.TURBO-MINI.COM

"Phil, I'd like to see a pressure gauge connected to the carb vent pipe (without it tee-pieced into the plenum-regulator pressure hose).
If this shows that the air pressure in the float bowl rises with boost and doesn't fall away, you can effectivly rule out the plenum, regulator, lines, etc - the fault can only be insdide the carb... "

Tried this tonight, plenty of pressure in the float bowl stays above boost and does not drop off .......
Guess it's carb change time !
Cheers
Phil.

WWW.TURBO-MINI.COM

what about fuel preasure, have you tried fittinga t peice inline with the fuel to the carb via prv, if this drops with the lean out then could be a fuel pump or fuel feed problem, worth a try before ripping the carb off.

just a thought

always looking for them bigger bunches of bannanas

Phil I had the same problem a while ago
drove me Feckin mad
had the carb to pieces dozens of times and went through 3-4 rebuild kits and bits

Tried everything listed above
Bar the drilling the 2.9mm hole

I even too it to a local SU specialist who couldn't see anything wrong with it.

Changed to another carb and hey presto worked
Some carbs just don't seem to want to play ball

Hoggy, Phil mentioned in his 1st post "reulator is set at 3.5psi at idle and rises accordingly with boost"

Some carbs are strange, and as an engineer it annoys me to say that... I know that the ports in mine are clear enough to get a wire rod through, but it won't pressurise the float clamber no matter what (so i use the tee-piece mod). It did work before sitting on a shelf whilst the engine was re-built mind! Very annoying!


Note to self - don't bid on a 'turbo' carb that turbophil is selling on ebay!!!

WWW.TURBO-MINI.COM

Never underestimate the usefulness of some choice items of "stock".......

Well, tried a new carb. Absolutely no Fucking difference !!!!
Tried a new regulator. Absolutely no Fucking difference !!!!

Tried everything i can think of and i'm real pissed off.

I don't like Minis anymore ................ lol

Phil.

WWW.TURBO-MINI.COM