marlono1 Posted July 11, 2022 Report Share Posted July 11, 2022 Hi Admin, I want to stop using the OEM relay used for the fuel pump as its giving me problem. Can I get an idea how it should be hooked up to create an aftermarket relay. OEM way i have a ground connected to ECU output before connecting to COR(Fuel Pump Relay) https://www.rollaclub.com/wiki/index.php?title=Circuit_Opening_Relay_Wiring 475773540_PCDatalog-2021-10-1085457pm.llgx Quote Link to comment Share on other sites More sharing options...
Adamw Posted July 12, 2022 Report Share Posted July 12, 2022 Timboj 1 Quote Link to comment Share on other sites More sharing options...
marlono1 Posted July 13, 2022 Author Report Share Posted July 13, 2022 thank you Quote Link to comment Share on other sites More sharing options...
marlono1 Posted July 14, 2022 Author Report Share Posted July 14, 2022 Hi admin I was not successful in powering up the Fuel Pump. I made wiring exactly as describe. I know each line is correct because its the same Ign Switch power i am using for my main relay. If I bypass the fuel pump relay with straight power it comes on. Quote Link to comment Share on other sites More sharing options...
Adamw Posted July 14, 2022 Report Share Posted July 14, 2022 So with ignition switch on, if you ground relay pin 85 with a small piece of wire or similar, does the fuel pump run? Quote Link to comment Share on other sites More sharing options...
marlono1 Posted July 19, 2022 Author Report Share Posted July 19, 2022 so it works when i have 85 sent to ground. this way its running only of ign switch and not via ECU switch Quote Link to comment Share on other sites More sharing options...
Adamw Posted July 19, 2022 Report Share Posted July 19, 2022 So you have wired something wrong then. Can you tell us what ecu you have and what aux you have wired the relay to. Quote Link to comment Share on other sites More sharing options...
marlono1 Posted July 19, 2022 Author Report Share Posted July 19, 2022 i am using atomX aux 4 to 85 ign switch 86 12v (20A Fuse) 30 fuel pump 87 When I use OEM relay AUX 4 to Y connection one to ground and the other to relay(OEM) works with no problem Quote Link to comment Share on other sites More sharing options...
Adamw Posted July 19, 2022 Report Share Posted July 19, 2022 So with aux 4 set to test ON, what voltage do you have on relay pin 85? Quote Link to comment Share on other sites More sharing options...
marlono1 Posted July 21, 2022 Author Report Share Posted July 21, 2022 Aux test is set to ON 85 aux 4 shows 0v 86 ign switch 12v while cranking it still shows 0v on aux 4 side Settings for Fuel Pump Quote Link to comment Share on other sites More sharing options...
Adamw Posted July 21, 2022 Report Share Posted July 21, 2022 12 minutes ago, marlono1 said: Aux test is set to ON 85 aux 4 shows 0v 86 ign switch 12v This is correct. If you have 12V on one side of the relay and 0V on the other side then the relay should be on. Quote Link to comment Share on other sites More sharing options...
marlono1 Posted July 21, 2022 Author Report Share Posted July 21, 2022 But its not, Car does not start. I have a fuel pressure gauge and it generates no pressure this way. If I use the OEM Relay i must route a ground and aux 4 together in series with a ground for it to work. OEM way has it routed this way with OEM ECU in order to work. If i route the Atom ECU the same way as the diagram above it also enables the Fuel Pressure with the OEM relay. Quote Link to comment Share on other sites More sharing options...
Adamw Posted July 21, 2022 Report Share Posted July 21, 2022 A relay is a very simple device, it only needs 12V on one side of the coil and Ground (0V) on the other side for it to engage. Which your test above shows you already have. You will need to get someone more experienced involved if you cant understand the circuit. Quote Link to comment Share on other sites More sharing options...
marlono1 Posted July 21, 2022 Author Report Share Posted July 21, 2022 it works now thank you Admin. Quote Link to comment Share on other sites More sharing options...
Adamw Posted July 21, 2022 Report Share Posted July 21, 2022 Aux 4 is the ground. Quote Link to comment Share on other sites More sharing options...
marlono1 Posted July 21, 2022 Author Report Share Posted July 21, 2022 thank you but unfortunately I don't know why it wont work that way. I have to connect a ground in between 85 and aux 4 for it to prime the fuel pump. nonetheless i wont touch as it works this way with a an aftermarket relay Quote Link to comment Share on other sites More sharing options...
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