Owners Club

Which engine loom do you have?

guessed it was the problem, relay for both fuel pumps controlled via ECU and engine loom connection to main loom, rely then feeds LP pump through main loom and HP through main/engine loom link plug.

the fact everything else switched on means the Ignition switch is OK,

you have a engine loom issue.

There is a schematic, but it would be of little use in diagnostics.

https://mega.nz/#!HoAWQIIQ!DFwF_QjjQof69zMEfot425_I8CbtIpYjnDW866qW-bo

As the Megasquirt is not supported by GBS, so the ECU sub loom must be bespoke.

ECU pin 37 controls the fuel pumps in my info, this should be connected to pin 5 of the grey plug (green wire)

this will switch the pump relay in the fuse board.

The connection to the rear pump is internal to the main loom, the connection to the front pump is via pin 12 of the grey plug (grey wire).

Are you able to tell me who gave you the info re the main relay? it has never been wired that way and is basically wrong.

There are two relays on the Fuse board that are for power, one is under a cover with the fan relay, and has nothing to do with the ECU, the other is under the second relay cover and is controlled via pin 3 of the grey plug, but I can not see a power control output on my Mega info, you can NOT use pin 37. Hopefully your fitting instructions include one.

https://mega.nz/#!2sB20QgR!VOJic6EMkfOOcV6ydmzItG5fZoBLK0wFxwTGvjuI8sE

Remember ALL ECU switching is to ground, and all relays are controlled by ignition so you could ground pin 3 to switch the replay on with ignition

The power from that relay comes down pin 2 of the grey plug (red wire) and is used to power injectors, coil pack etc.

this is the grey plug pin out

https://mega.nz/#!6soF1D5Y!AHR0bE0VzgkfFKi7rPzA4Euc2VyTZovkXV8z_-3UEb4

Could put together a connection diagram if you wish, but I would need to know the ECu pin out you are working with. Megasquirt is an open source project, and there are a lot of "versions" out there.