Donations towards server fund so far this month.

£0.00 / £100.00 per month
Home > FAQ / Knowledge > Mini / metro turbo not running correctly? THEN START HERE!!!

Forum Mod

10967 Posts
Member #: 17

SouthPark, Colorado

This guide makes a few assumptions:
1) That you're mechanically competent and able to follow basic instructions.
2) You've got good fuel in your tank, oil in your dashpot, a spark at the spark plugs, correct cam and ignition timing, etc... Basically, that you've checked ALL the basics.
3) That you've got an in-car boost gauge fitted (essential for any turbo install)
4) That you're mechanically competent and able to follow basic instructions. (Repeated in case you can't follow instructions - thought you might notice it the second time).

Most of the running problems seem to be fuelling related. They're also the 'cheapest' to fix, so that's where we'll start. Firstly, look at this picture and familiarise yourself with it and compare it to the SU carburettor in your turbo mini / metro.

Firstly - check that the hose running from pipe [3] to[5] is intact and not split. If it's the original pipe, it's a shiny, plastic-like finish. These have a habit of getting a hairline crack, which is difficult to identify. Best solution is to remove the old pipe, then replace with a short piece of 1/4" fuel hose (EFI grade).
Give all the hoses to and from the regulator and carb a good visual inspection at the same time.

Any better? If not - continue reading...

Next thing to check is what is connected at pipe [4]. The metro turbo had a 'carb vent solenoid' fitted here. The solenoid closes when the ignition is switched on. This solenoid is known to be unreliable, and often fails to close properly. Easy fix is to remove the solenoid and blank the pipe with a shouldered bolt or piece or rod rammed up the hose to permanently block it. To check - a hose clamp or set of mole-grips will create a temporary 'block'.

Any better? If not - continue reading...

Now you need to get hold of a pressure gauge, and a 1/4" Tee-Piece . A simple 0-15psi gauge is ok - but be carefull not to over-pressurise it in the following tests.
1) Disconnect the 'fuel inlet' rubber hose [2] at the carburettor. Connect the rubber hose you just removed to one leg of the Tee-Piece. Connect the second leg of the Tee-Piece to inlet [2] in the diagram with a short piece of 1/4" rubber hose. The last leg of the Tee-Piece is connected to the gauge. This is a little tricky as you want to try and position the gauge under the wiper arms (so it's visible from the drivers seat) and feed the hose through to the Tee-Piece.

Don't start the engine yet - but turn the ignition (fuel pump) on. Once settled, the pressure should read 3-4psi. Adjust regulator if neccesary (11mm spanner and flat-blade screwdriver).

2) Now you need to check if the fuel regulator is increasing the fuel pressure relative to boost pressure. Go for a short drive. You'll notice as you approach the 'boost transition point' (ie - ZERO) on your in-car boost gauge the fuel pressure on your 'wiper arm' gauge will rise. If all is well, it should have increased from 3/4 psi at tickover to 8/9 psi at the 'boost transition point'. Therafter; it rises proportionally with boost (ie 5psi on the in-car boost gauge = approx 13/14psi on the 'wiper arm' gauge). If it does - all is good with the regulator plumbing and the regulator.

3) Remove the Tee-piece, re-fit the rubber hose to [2] as it was before you started (for reference, this should connect to the top-most connection on the fuel regulator) - basically as everything was to begin with.
Now disconnect whatever hose is fitted to [4] on the carburettor. Now connect the 'wiper arm' pressure gauge to this point. Go for a short drive. As before, you should notice the pressure rise up to 8/9psi, at the 'boost transition point' and proportionally therafter.
If it does not, then either the internal porting in the carb has become blocked, or an incorrect gasket fitted between the carb and plenum. There is an easy fix however - it's called the 'Tee-Piece Trick' and bypasses the internal porting.
More information on how/why can be found here:

If it doesn't work after that, the next suspect is the ignition system.
The first check is that the ignition amplifier is recieving 12v; the majority of minis built in the 1980's ran 'ballast' ignition. Basically, these only send 9v to the coil. Confusingly, if you measure it with your voltmeter - it'll read 12v however, as it only drops to 9v when a load (eg an ignition coil) is connected across it. The 'ballast' ignition system is identified by a pink/white wire connected to the coil. If in doubt, locate an ignition live on your fusebox and run a wire from there straight to your distributor.

Next, the amplifier module on the 65DM4 distributors is known to cause problems - especially if an aftermarket sports coil is used instead of the correct 'black' 12v electronic ignition coil from Lucas. The stock setup has been proven to be more than adequate for even extreme nitrous-assisted engines, so there is no need to change.
When the module does start to fail, it'll often work fine at tickover or when the engine is revved freely. Only when the ignition system is under more load as boost starts to build, will the module break down. When replacing the module - remove the old unit and clean the distibutor body where the module mates with steel wool or emery cloth. The new module should come with a special heat-conductive jelly. Apply a thin smear to the back of the new module before screwing to the distributor body. Failure to do this will kill the new module in only a short time.

Done all that and still got problems? Ask in the forum, and (assuming you've tried all the above) you'll get lots of help - more so than if you've tried nothing at all*wink*)

Edited by TurboDave16V on 5th Jul, 2013.

On 17th Nov, 2014 Tom Fenton said:
Sorry to say My Herpes are no better

Who remembers this first time around:

Site Admin

User Avatar

9392 Posts
Member #: 58
455bhp per ton
12 sec 1/4 mile road legal mini

Sunny Bridgend, South Wales

good job Dave

Team Racing

On 15th May, 2009 TurboDave said:

I think the welsh one has it right!

1st to provide running proof
of turbo twinkie in a car and first to
run a 1/4 in one!!

Is your data backed up?? one extra month free for all Turbo minis members, PM me for detials

Site Admin

User Avatar

8506 Posts
Member #: 16
Sold the turbo and seeing what the C20XE can do!

Near Lincoln

Good job and ill lock it now so no questions get asked here *smiley*

Home > FAQ / Knowledge > Mini / metro turbo not running correctly? THEN START HERE!!!
Users viewing this thread: none. (+ 1 Guests)  
To post messages you must be logged in!
Username: Password: