Mini turbo won't rev past 2500 rpm
Turbo Mini Forums

hi all

just finished the last things i had to do to put the mini back together, started first time but didnt sound right, just put it down to not being started for a couple of months so took it on a test drive and it wont rev past 2500 rpm, i can hear the turbo starting to spin but nothing happens after that, noticed abit of smoke coming from the turbo side aswell

a quick list of things i did when the mini was off the road

removed turbo and fitted new oil feed pipe
moved the electric fuel pump from under the car to the boot floor
fitted new exhaust

could this be a fueling problem as i've moved the pump as looking on the net that was one of the things that was mentioned or is the turbo knackered

any thoughts on this would really help me out

cheers all

The smoke may just be oil burning off the housing if its from the turbo itself, done this a few times on my LCB after messing with stuff, so much so on occasion I've thought something to be on fire
Sounds daft but check you haven't trapped any fuel hose if that's what you've been messing with, or that it isn't kinked behind the tank if you've had it out. Good luck getting it sorted!
Edit: if the fuel pump is earthed via the body of the car, make sure you're onto good clean metal, otherwise the resistance would let the fuel pump run, but at a much reduced rate.

Edited by Carlzilla on 9th Jan, 2012.

Have you checked the fuel pressure?

Mind you id expect it to cut out if it were being starved?

1/4 Mile 14.3secs 96Mph Terminal 10psi of boost.


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Mine Once did this because there was no fuel pressure

Pop another good earth on the fuel pump. It can't do any harm.

I can't see how this will make any differance.

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

Have you had the plenum chamber off?? Check the gasket is the correct way around between the carb and the plenum, sounds like the fuel pressure in the carb may not be rising with boost. Also check the pipes are correct on the fuel pressure regulator.

Team Racing

cheers for the feed back guys, think you all could be right about the fuel issue, when it drives as it hits 2500 rpm it bogs down as if its running out of fuel, just brough a fuel pressure gauge off ebay to check the fuel pressure, will let you know how i get on, thanks agian everyone

Just remember that the pressure increase in the float bowl is not caused by increasing fuel pressure between the FPR and the carb.

Is the restrictor fitted in the plenum? this is key to the whole thing working.

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

by the restrictor i take it you mean this



didnt take the plenum chamber apart this time and had trouble a couple of months ago when i replaced the plenum chamber gasket, i put it all back together with the restrictor round the wrong way and when i drove it that sounded like the dump valve was permanently open and it didnt feel like the way it drove yesterday

if thats not the restrictor then dont know what bit it is

when i took the turbo out i didnt take apart the plenum or the carb so dont think it could be a bad gasket or blocked hole (can remember the exact bit but its what some people use the T piece method to fix)

No, that's a pressure relief valve tha topens at 10spi to stop over boosting. You'll need to block this if you want more boost.

The restrictor is a copper coloured ring at the carb mouth.

You definately need to check that the hole to pressurise the float chamber from the plenum is not blocked by the gasket. The symptoms that you have are exactly what would happen if it was blocked.

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

cool, right how do i check that copper coloured ring, if you have a pic of where its placed that would be a great help, asoon as i see how something works or where it goes i can get it, know that sounds abit funny but just the only way things stay in my head

thinking about it when i took the carb and plenum chamber off i did turn it upside down and move it around the garage a couple of times, could this have dislodged it

I think you may have misread Wil's post. I think he's reffering to the little hole to the left of the plenum chambers hole, on the face that it mounts to the carb. The middle hole on the left in the picture below (not my plenum)
You may have a put a non turbo gasket on and blocked it up accidentally.

Edited by Carlzilla on 10th Jan, 2012.

got it, i can see what you mean now, but thats the thing i havent taken the plenum off of the carb so not sure how this hole could have become blocked

You can see the restrictor ring in that plenum. Brass coloured ring inserted in the the large inlet hole.

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

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I know I sound like a broken record, but...

Check the part throttle lean off pipe.

In the 13's at last!.. Just

I know i'm only a newbie but my first car was a metro turbo (many years ago) and i had the same problem, it turned out to be the anti-run on valve. just removed it and bunged the pipe with a bolt as its not overly needed. thats if you have one fitted.

Have to agree with the above. If either the part throttle lean off pipe or float chamber vent valve pipe or solenoid are leaking you will experience the symptoms you have described.

Remember your fuel pressure should be 3-5 psi at idle and increases linearly with boost pressure. So 10psi of boost will see you at 13-15psi of fuel pressure. If not you have a leak.

Own the day

bit of an update:

think the problem is the fuel pressure regulator, plumbed in a pressure gauge and it read 6psi with the key turned so the fuel pump turned on and at idle aswell, wound the adjuster all the way out (so a single part of the thread was engaged as completely unscrewed it then did it thread by thread) and it read 4.75psi and when i wound it all the way in it still showed 6psi

I'm guessing from this the regulator needs to be replaced

got me a couple times in the past, now i always double check before fitting

Yes i moved to the darkside

Instagram @jdm_brett

So it is a fueling problem the regulator should go way higher than that. What pump are you using and what size fuel feed and return have you fitted?

Own the day

imo the regulator sounds like its past it but at 6psi fuel pressure at idle the engine should still run into boost untill the float bowl is empty
the fuel pressure fills the bowl, it doent fuel the engine on boost

Yes i moved to the darkside

Instagram @jdm_brett

Exactly Brett. You could turn the pump off and the engine will still run fine.

The problem with your test is that as soon as you exceeded the pressure that the needle valve will resist you won't get any more pressure nomatter how much you turn the reg. all that will happen is that the fuel will piss out of the jet.

Have you checked all of the above that have been mentioned?

Just another thought. Are you using the turbo dizzy? Check that this has 12V, if wired via a ballast resistor wire they end up with 9V and don't work. It may also be the case that it's FUBAR, they commonly fail and give all sorts of odd sympoms.

Edited by wil_h on 25th Jan, 2012.

Fastest 998 mini in the world? 13.05 1/4 mile 106mph