25 replies to this topic

[Fred320]

Does anyone have a wire diagram that shows one wire going into the interior light (br/gr) and two exiting (switch side) (w/p) to pump and (n/s) fuel gauge sensor?

[sonscar]

The fuel sensor wiring will go to the cluster,it will not be in series or teed to any other wire or it will not work.The pump will not be in series with the interior lamp though it may be teed off the same live.This assumes factoryish wiring.the pump is connected to an ignition controlled live,the lamp is live all the time.Could be wrong but relays would not have been a 1978 fitment so the wiring sounds like it is non standard in which case you may have to manually trace each wire.Enjoy a good faulting session,Steve..

[humph]

The forum’s comprehensive wiring diagrams are here if you haven’t found them.

 

https://www.theminif...agrams-redrawn/

 

The wiring diagram for your car description doesn’t show an electric fuel pump, and from the colour of your wire it sounds like it’s been added later as switched lives are usually white. Check out the Riley Elf or Cooper S diagrams for how BMC wired their fuel pumps around that time.

 

This is Cooper S

 

https://www.theminif...ttach_id=193828

 

Where are the relays in the set up? Obviously not standard. So sounds to me that the permanent live to the relay is off the light, then a switched to the relay from the ignition.  What happens if you bypass the relay by connecting the switched live directly to the pump? 

 

Anything else using the relay? Do they work? You’ve checked the pump earth, but the relay will have it’s own earth to operate.
 

Edited by humph, 23 September 2023 - 05:52 PM.

[nicklouse]

Do we know what pump it is yet? Or even where it is located?

[Fred320]

Electric pump in the boot against the tank. It has 4 pin relays x4. As I have already stated it is a 1978 mini with a 1275 fitted and possibly 1980's electrics with a single carb. All relays and fuses are functioning. The live feed to the pump white/ purple same as one the interior light(in brown/green). The other off the interior light is brown/slate. The fuel gauge sensor is feed of the brown/slate. That is what see. The pump was functioning correctly on Thursday and for the time I have owned the car. I can't say why it has suddenly stop working as I haven't changed anything. What you say maybe correct but they are the colour of the wires and what they're connected to. I didn't not fit anything it was how I purchased it. The only change is from points to electronic ignition.

[Fred320]

The wiring is a SPI 95-96 so it may have a fuel pump inertia switch. I will check that tomorrow.

[humph]

Fuel pump for SPI appears at the bottom of this diagram. Doesn’t match your wiring as the fuel pump is fed by the master relay pack fitted to the injection cars, and you don’t sound like you have that, so this wiring diagram isn’t of use to you.

https://www.theminif...ttach_id=193841

 

As per my previous question really. There will be two live feeds to your relay, a permanent which appears to be the one from the light, and a switched from the ignition. What happens if you connect the switched directly to the pump? If it runs suggests issue with the relay, it’s permanent live feed, or it’s earth. Have you investigated the relay earth? Can you hear the relay click when someone switches the ignition on?  
 

All 4 relays can’t be for the fuel pump surely?

[weef]

I think you will have to start with a blank sheet.

You will nave to identify the following.

The route the wire takes from the boot mounted pump to the engine compartment and it has continuity between the boot and the engine compartment.

1  The relay that controls the power for the pump.

2  The initiate supply for this relay coil, normally ignition fed .

3  The earth path for the initiate relay coil.

4  The supply to the relay normally open contact, either an ignition fed or permanent live but fused either way, this is the pump feed.

Once the wiring is identified rewire the pump power supply feed as follows.

The relay initiate coil supply, wire2, to one side of the relay coil.

The relay coil earth, wire 3, to the other relay coil connection.

The pump supply , wire4, to one of the relay switched contact connections.

The wire identified as that going to the boot mounted pump to the other relay switched contact connection.

 

If the pump has a good earth connection it should now run when the ignition is switched on.

[nicklouse]

The wiring is a SPI 95-96 so it may have a fuel pump inertia switch. I will check that tomorrow.

Is the engine an SPI?

[Fred320]

Yes the previous owner did if SPI wiring but remove wiring for alarm and fuel injection. And for some reason I can't work out the inertia fuel cut off switch! I believe I have fixed it now just need to test drive it🤔😳

[Fred320]

Does anyone have a mini sprite wire diagram carb model?