Corrrect way to wire in the fuel pump.
Turbo Mini Forums

I have seen several posts asking the correct way to wire up the fuel pump on a Mini/Metro Turbo. Most suggestions deviate considerably from the original Leyland way. Using just a simple relay, energised via the oil pressure switch, leaves you stuffed if there is no fuel inthe carb. On my website http:/www.eraturbo.com there is a diagram and a description of how the correct circuit operates. All circuit references are to the ERA Mini Turbo, but the circuit in the Haynes Metro & MG Manual (0718) is identical to the one given on my site, just drawn a bit confusing. Go to website. Click on Technical in Header List and then on only link shown.
Hope this helps.
Kayball

The metro wiring scheme would never have passed type approval after 1990 when things were tightened up... EVERY car with a high pressure electric fuel pump should have the ignition feed to the coil and the feed to the fuel pump wired via an inertia swith. No excuses or concessions.
In an accident these switches kill any sparks and all the fuel supply in one hit - don't assume that because your car is in an accident the engine always stops...

When i used to do banger racing, i ended up on my side in one race and after i'd undone my harness, and climbed out, i realised the engine was still going!!! (around 60 seconds later...)
If that had of been on the road, i could have ruptured a fuel line or anything - and fuel would have been gushing out - and these pumps deliver a heck of a lot of fuel...

Don't assume that even a simple front end smash on the road, which would kill the engine 'cause the dizzy was broken into little pieces would ensure the pump stopped - Imagine the oil pressure wire got severed and earthed against the block / bent panels - the fuel pump would carry on running, even if the engine was VERY dead...

I would NEVER, EVER run a car on an electric fuel pump without an inertia switch - unless doing rallying / off-road racing, where it could be tripped inadvertantly, but lets be honest - this doesn't apply to us!

FYI:
Inertia switches are found most easilly on all EFI Fords.
For example...
Sierra injection saloon (early) mounted in spare wheel well.
Sierra late - Drivers footwell on A-Pillar, behind the trim panel
Mondeo - Passenger footwell on A-Pillar, behind the trim panel

WHEN you get one, snip of a few inches of the wire aswell - so you can get the plug, and enough wire to play with.

On a turbo, it is essential to wire it in so that if it trips, it kills the pump AND the engine. The reason for this is simple - if it was tripped inadvertantly (say hitting one of the rumble strips really hard on a trackday, whilst doing 6000rpm at 15psi), you'd see a rapid leanout and meltdown of the engine if the pump stops. Much better to kill the lot and avoid problems..

Hope this helps - as you can guess, i have a particular concern about this, and hope ALL of you heed my advice - i certainly don't want to be visiting any of you in the burns unit, because your fuel pump carried on pumping whilst you were knocked unconcious whilst a small fire erupted near your severed fuel lines...

Edited by TurboDave16V on 21st Oct, 2003.

What Dave says here makes alot of sense and we should all thanks him for the advice. I've worked in the offshore industry for many years and sparks and fuel do not make a nice mixture in any situation.

For an area to qualify as a potentially explosive atmosphere it must contain a flammable substance and air, and be under atmospheric conditions. An explosive environment includes anywhere that liquid fuels, flammable gases and explosives are stored or used.

Most explosions are initiated by a spark and when electronic equipment is used in a volatile environment the risk of explosion is increased. Switches, circuitry and motors all have the potential to create sparks. Wherever a circuit is broken or is close to being reconnected, electric currents can arc through the air.

If you want to see how complex and serious the issue is take a look here:
http://www.medc.com/Haz%20Area%20Guide.pdf

Be safe out there!!

It's all fun and games until someone gets hurt... Then it's hilarious!

Late model Metros also had a nice compact and easy to mount inertia switch on the passenger side inner wing, same unit on a lot of Rover's in a similar position. Just another option.

Every day is a school day ...........

How fast and how expensive ...... the same question...

An un-latched priming switch can also be fitted to bypass the oil pressure switch part of the system enabling you to prime the pump and ensure sufficiant fuel is supplied to the engine on start up before the engine oil pressure increases enough to run the pump that way.

As stated above an inertia switch to kill engine and pump is a DEFINATE if you want both your engine and yourself to survive