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Switched power


yetchh

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5 hours ago, yetchh said:

Ok cheers, how do I fix this? Should the ecu run on its own separate relay? Where would I find these flywheel diodes in a 70's mazda? 

I thought the flywheel diodes would be in the ECU itself?

If not, i put a "schotcky diode" to short a relay, but only if the relay is hooked up backwards. Seems to flywheel ok for the most part.

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11 minutes ago, Stu said:

From memory there is an updated wiring diagram on the link FAQ on how the ecu needs to be powered.  I can dig up the wiring diagrams for the last few customers cars Ive wired up if you want too.

Yeah bro that would be good.. It does say in both the v3 and v5 installation manuals that inj, ign and ecu can be on the same relay, I guess I just took a shortcut and put the fuel pump on there as well.. 

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where does the 12v+ come from on the coil of fuel pump relay ?

Sounds like how you have it setup should work. 

Ideally  you want  your main power feed from battery  -> straight to fuse box/ fuses .  then out of fuses to relays

I like to run the ecu on its own relay  triggered by key on.
Then a second relay for the fuel pump.   ecu supplies negative to coil
Then if you want to get fancy; As well as the fuel pump relay doing the fuel pump. use it to trigger the coil on a 3rd relay, which  does all your injectors,  coils etc.
This way if the engine stops for any reason, the ecu turns off the fuel pump and also kills power to injectors and coils and what ever else is on the 3rd relay.   just  bit of a safety feature

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1 hour ago, kpr said:

where does the 12v+ come from on the coil of fuel pump relay ?

Sounds like how you have it setup should work. 

Ideally  you want  your main power feed from battery  -> straight to fuse box/ fuses .  then out of fuses to relays

I like to run the ecu on its own relay  triggered by key on.
Then a second relay for the fuel pump.   ecu supplies negative to coil
Then if you want to get fancy; As well as the fuel pump relay doing the fuel pump. use it to trigger the coil on a 3rd relay, which  does all your injectors,  coils etc.
This way if the engine stops for any reason, the ecu turns off the fuel pump and also kills power to injectors and coils and what ever else is on the 3rd relay.   just  bit of a safety feature

 

Fuel pump feed comes from the +common fuse box fed by the a 12v battery direct relay, 

I drew it out...  

 

IMG_20200113_211515.jpg

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so  is like this now and works?3.png.a97e4cdb323461a5bc20a468a4880cf8.png

can kinda see how that would fix the issue to a point.   bit of a band aid fix though.  with ecu wired on that side what ever is backfeeding that relay wont be enough to power the ecu, so engine will shut off.     you may still end up with battery draining issues or other weird stuff
I still think your better off to ditch that "main" relay before fuse box and run a couple of relays after the box one for ecu and other for the rest,  fuel pump can stay how it is. assuming "to ecu earth" is the fuel pump output from ecu

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Yeah I'll put a relay and fuse for the main ecu power separate from the main relay, the rest should be good like that. The coil energiser for the pump came from the main relay like everything else then to the ecu switched earth, I just ran it straight to the ign feed to see if it fixed it which it did.

 

 

 

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