Spent some time reviewing the FSM's to work out the wiring of shoving the z31 ECU into the X. So far I think I can use the z31 ECU to trigger the X's fuel pump relay no issue. Also if you ever want to see a way to complicated fuel pump setup review the 300zx diagram uses two different ECU pins and a relay.
Looks like the gauge cluster doesn't use the ECU except for the tach which uses a signal from the ECU to give the tach output. The z31 uses an old style tach which uses the coil to get the reading. Did some searching lots of adapters to go from the ECU output to an old style tach but couldn't find anything to convert coil pickup to a 0-5v square wave the X cluster is looking for. Eventually found an adapter for a race logging box called the CoilX looks like I should be able to wire it up to the old z31 coil I am swapping over and it will give out a square wave.
CoilX Link
https://wiki.autosportlabs.com/CoilX
If anyone has any experience on something like this feel free to share.
What the X cluster is looking for from the FSM.
Looks like the gauge cluster doesn't use the ECU except for the tach which uses a signal from the ECU to give the tach output. The z31 uses an old style tach which uses the coil to get the reading. Did some searching lots of adapters to go from the ECU output to an old style tach but couldn't find anything to convert coil pickup to a 0-5v square wave the X cluster is looking for. Eventually found an adapter for a race logging box called the CoilX looks like I should be able to wire it up to the old z31 coil I am swapping over and it will give out a square wave.
CoilX Link
https://wiki.autosportlabs.com/CoilX
If anyone has any experience on something like this feel free to share.
What the X cluster is looking for from the FSM.