More problems, Next culprit, Main Relay.
Turbo Mini Forums

Right, Im getting quite annoyed at this stage with this system, its been running in the car a month and Im quite annoyed at all the little stupid problems that should be Ironed out.

Car was misfiring under load and generally being crap, so I parked it until I got the time to sort out the list of issues I have from the first few weeks. I have all them sorted, went to start the engine, nothing. Im not getting fuel to the Injectors, the pump isnt even priming.

I have ruled out the following

Pump.
Wiring
Fuse

So all I am left with is the main relay, got a multimeter out and checked the circuits, 12v is going to the ECU, however, the relay isnt switching the relay to turn the pump on and prime it. Neither is it providing power to the other 3 circuits its ment to power.

Is there anyway of checking the relay? Ive continuity on the off position, but I dont know how to test the other parts as obviously when they are switched to off I get no continuity. Relay has been running in the car a month, all connections are clean and have no corrosion all wiring is tight and in place.

A outside chance could maybe be the switch wire from the ECU? however I can hear a "click" about 3 secs after the ignition is switched to on. Would the injectors make this noise even with no fuel (priming pulse).

Any help would be appreciated, as I dont want to run a switched 12v to the pump.

What are we looking at here? Spi/ MPi/ bits of either? I have a short memory

I wrote this a while ago>

Description of the relay pack control.

This is the likely scenario you will experience on the SPi engines, this however may differ slightly between years as Rover changed the wiring as far as i can see about 4 times. Slight changes may be experienced, but for the most its the same.

Coil side of relay pack (small connector)

+ve supply to the relay coils

The main relay is permenantly supplied with 12v (internal), the fuel pump relay is supplied with 12v from the IGN position on the key switch (white), the manifold heater relay coil is supplied with 12v when the main relay is energised (internal but common to brown pink), the starter relay coil has two options depending on year. One, the starter coil is supllied with 12v when the key switch is turnd to CNK (white with red). Two, the starter coil is supplied with 12v when the key switch is turned to CNK (white with pink). Note the latter, the wire from the starter switch is white with red, then changes to white with pink through the body to engine loom connector.

-ve supply to the relay coils.

The main relay is grounded by the ECU (white with pink), the fuel pump relay is grounded by the ECU (black with purple), the manifold heater relay is gounded by the ECU (black with pink), the starter relay has two options depending on year. One, the starter relay is grounded (black pin4). Two the starter relay is grounded by the alarm ECU ( white with red). Note the latter, the wire from pin4 of the relay pack changes from white with red to white with pink, through the body to engine loom connector.

Main switched power supply (large connector)

All four relays are fed with 12v from the battery (brown). Main relay switched live is brown with pink. Fuel pump switched live is brown with slate(grey). Manifold heater switched live is brown with blue. Starter switched live is brown with red.


Logic explained

When the key switch is turned to IGN 12v is supplied to the ECU on a white wire this powers the ECU. The ECU will then initiate the fuel pump for 10 seconds and then de activates it again if there is no further activity. Turn the key to CRK the starter is initiated (if the imobiliser/alarm is off, where fitted). Activity is recorded by the ECU on the Crank Position Sensor. The ECU then initiates the Main relay. This provides power to the ignition coil, stepper motor, purge valve solenoid, and ECU directly on the brown pink, and the injector via the ECU. The engine should now start. Once the RPM is above a predetermined RPM the manifold heater is initiated until the coolant temp measures 75c or more it is then de activated. The Main relay, and fuel pump relay, are the only ones to be energised when the engine is running and fully warmed up.

On 20th Jul, 2011 Sprocket said:
What are we looking at here? Spi/ MPi/ bits of either? I have a short memory

Schrödinger's cat - so which one am I ???

The "click" comes from the area of the relay, however the injectors are quite close so it could be either. I was thinkin that it could be the priming pulse, however if you say the injectors dont make much noise Id say its the relay.

If it is the relay, I think I may have another issue, which I cant figure out, I have checked the inertia switch, which is fine too. If it was a short, the fuse would blow no?

So If the relay is working, why isnt the Pump getting power, or any of the other 3 ECU circuits?

Pump definatley isnt running, it does run when I run a wire from the battery + to the pump +, so thats the pump ruled out too.

By seperate fuel pump relay what do you mean? The set up I have is follows.

Switched live to secondary fuse box, this live then goes through a fuse and on into the relay and powers the ECU.

The following part is how I understand it to wok:
A signal from the powered ECU switches the Relay and this in turn powers the Pump and the other management circuits.

The info is on page 49 of the manual here: http://www.canems.co.uk/pdf/injection_manual.pdf

I have no Idea as if the relay is switching, I should hear the pump running.

Looking at page 59 of the manual (as well as page 49), it appears to use one relay for everything.....

(most ECUs have a seperate relay just for the pump as it's only the pump that requires the "priming" pulse)

So, on the basis that you say the pump AND the other 3 ECU circuits aren't working, either the relay has failed internally (it could still click but the contacts could be burnt out) or the 12V feed to it is dead.

Was it provided as part of the kit ??? It needs to be quite highly rated as it's doing everything.
And is it in a plug-in socket ??? ie, just plug another one in and see.

But first I would check it actually has 12V getting to it - possibly the 12V supply has been taken from somewhere in the main loom that is already fused at less than 50A (that's the total of the three loads out of this relay) so a completely seperate fuse in the original wiring/fusebox could have blown.

Schrödinger's cat - so which one am I ???

There are 12v going into it for sure, I checked the whole fusebox wiring. The fuse seems to be okay, but I will check it again, The fuses are those ones not in clear plastic, just with a hole cut in the middle so you cannot see 100% of the fuse (duh).

The relay is rated at 40A , there is a possibility it has burnt out, but after a month of not so frequent use(maybe twice a week, it wasnt been running in a week and a half) I'd be surprised. Ill head down to the motorfactors and get another and give it a shot. Everything has been provided as part of the Kit, only wiring I did was run a 12v feed from the Canems fuse box to the tank, which has been ruled out.
The Relay is plug and play so should be handy to just switch around.

Im not very happy with this failing so quickley, I was expecting the canems system to be abit better than this.

A 40A relay should be fine - although the three circuits it is feeding are fused at a total of 50A, they will never all draw their maximum rating at the same time.

My concern was whether your 12V supply to the relay is possibly fused somewhere back in the stanadrd loom at a lower value.

Where did you run the 12V supply TO the canems relay from (not the one from the relay to the pump but the one providing 12V to the relay).

Schrödinger's cat - so which one am I ???

the permanent 12V comes from the starter solenoid. The switched live is from the Top Fuse on a 4 fuse fuse box on a 1990 Cooper. Its a fairly hefty looking fuse. Now Ill have to go out and confirm which is going to the relay.

Edited by ciaran on 21st Jul, 2011.

found the problem, the permanent live from the solenoid has disconnected itself. TBH i totally forgot about it until you asked where the power was coming from! I was just checking the circuit from the switched live.

Dumb me haha.