A little background: If you plan on using a double pumper with the stock fuel lines fuel pressure can become a problem unless the pumpers are staged using hobbes switch which is included with the Buschur Double Pumper kit. I decided against this low tech method and decided to expand the capabilities of AEM EMS instead.


Materials:
- Double Pumper - $500
- 10 Gauge Wire (8ft) - $6
- 14 Gauge Wire (20ft) - $6
- 10 Gauge Fuse Holder - $4
- Shrink Wrap (various sizes) - $5
- LED for Activation - $5
- Relay + Harness - $8
- 3 Ringed Terminals
- 3 Female Wire Connector Terminals
- Solder
- Soldering Iron
- Screw Driver
- Electrical Tape
- Razor Blade
- Drill

Part A - Installation/Mounting

I started by locating the output wire on my harness. I choose to use High Side #3, which is pin 56 on Connector C.



Next cut the wire (make sure to leave a enough wire incase you ever decide to go back to stock) and then solder on enough wire to reach your relay.





I then drew power for the relay from the battery. You will want to solder in the fuse holder as well (sorry I didn't get a picture of this step). I used 10 gauge wire for this step.



Here is a wiring diagram for the relay.



I choose to use the seat belt bolt for a ground point. You can also wire a LED in between the ground and up to the dash if you want an LED alert when the second pump becomes active.



I picked up some 10 cent grommets to use to run the wires through the factory fuel hat cover.



I then ran the wire that was soldered to the ECU harness earlier up the center of the car and underneath the carpet



Relay all wired up.



I mounted the relay to back of the seat for easy access.



Now that the relay is wired up it needs to be set up in AEM EMS.

AEM EMS Setup

Under the "Options" tab click on "Configure Outputs"



Choose "HS3" or a different output if you used a different one.



Then choose the desired activation conditions. I choose to have mine switch on once 10 psi is reached. Scroll down to "Switched Output Configure" and choose "Switch is always on" If you want to verify that everything is setup properly, you can choose conditions in which the second pump will come on with the key in position 2 and you should hear it turn on. You can also log the parameter "HS3" to verify that its turning on.




The installation is complete! Adjustments to your fuel maps will more then likely be needed. Good luck!

 

Nice write up! Thanks

 

Hey quick question, on my evo 9 since the rear o2 sensor is deleted i can use pin 26 rear heated o2 Low Side 2 correct and the. Configure the setting from there?

 

Good write up by the way.

 

Thanks for that, FANTASTIC post. Helping a friend wire up this exact setup, potentially more reliable than Hobbs maybe...since you're omitting extra vacuum lines and sesitive "mechanical" switch?

 

Sorry for ultra late reply but yes you can but keep in mind the Low Side is a switched ground so you will need reverse the wiring and run a power wire to the relay but use Low Side #2 to ground it to initiate the relay activation. I actually use the low side for my shift light.



I haven't figure out how to trigger an ignition cut type of situation in case the relay does not activate. I prefer this over the hobbs because I have complete control over when the second fuel pump is active based on what AEM is seeing.

 

anyone can help me with my relay not firing up the second pump? im a aem v2, i tried to activate it but no luck.... aem says its active but the pump is not turning on. pump does work. the relay is new... someone pm me, so i can maybe have a phone convo for faster diagnosis... thanks!

 

Shadow x, try unhooking at your relay wire at your aem and applying voltage to check your relay and circuit. Some aem outputs are grounded when activated instead of positive voltage. On the aem EMS we are using on our squash double pumper build we are using the aem to GROUND the relay, with switched 12+ key/on on the other side of the relay. Also make sure you've got a decent gauge of wiring carrying your load circuit to the pump- anything smaller than 12 gauge is going to get hot under sustained load, those pumps can pull some substantial amperage.

 

I know this is old but thaks!! IT is justwhat was looking for

 

bye bye hobbs switch

 

good write up!! this is exactly how I run my double pumper set up

 

can i get a hand here. i have the same relay as above. so am i correct

30 ''white wire'' to battery
85 ''blue wire'' to AEM
87 ''black wire'' to + on the second fuel pump
86 ''yellow wire'' to ground

is that correct?