sl87

s13 Redtop
1601 Aem Ems
So I recently got everything hooked up finally. The fuel pump primes when the car is on the on position, just as it should. With the key in the ACC position, second turn of the key, I push in the brake pedal the pump primes. I hit the hazards, the pump primes. Use the turn signal, pump primes. Obviously something is definitely wrong.
The thing is I havent touched my fuel pump in like 2 years. During my build I didnt touch the fuel pump at all. The only wiring I touched was having to hook up gauges and hooking up the EMS. I did do repinning on the EMS for MAP and IAT sensors. I saw that on the EMS there is a Fuel pump relay pin but never had to touch it and never did.

I connected my old ECU and the problem did not occur. So its only happening when i hook up the EMS.
Anyone run into this problem and help me figure why my Fuel pump primes when an accessory unit is used (i.e. brake pedal, hazards, turn signal, and radio when turned on.)

j87w

I would start with double checking your wiring (make sure you connected the right wires into the right places). When I did my AEM EMS install I swear I did it all right and had a electrical issue with it and found out it was my own mistake (mixed up 2, same color and same gauge wires that were next to each other).

flexer

Look at the pin output. There is a pin out of the AEM that is a sensor ground. The ECU grounds the fuel pump relay and the ecu is programed to prime that relay for the set amount of time you enter in the AEM then shut back off till you turn over the motor. Then when the AEM senses that the motor is running it keeps the fuel pump relay primed to stay running. Check that wiring

J. R.

sl87

I checked the wiring for the fuel pump relay on the EMS and the grounds on the EMS. Everything is connected. I never touched those wires to begin with. The pump primes at the turn of the key just as it should.

GSXRJJordan

It sounds like your fuel pump and tail lights/brake lights share a ground, and they are grounding through the pump (and relay) when the relay is not energized. I'm assuming the pump works fine once you click it to 'on'?

Check the ground in the trunk on the tail light harness. If it looks good, and you want the problem to go away, separately ground the fuel pump from the tail lights/etc.

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sl87

Ive had this fuel pump in for three years and never touched the wiring and never had this problem before. Yes the pump primes just as it should at the turn of the key to the on position. The thing is, its not just the brake thats making it prime. Its when I hit the Hazards, use the turn signal, click on the rear defroster, or turn my deck on.

sl87

UPDATE:
Ok so Ive tried unplugging any sensor i could find and see if the pump will prime if i connect one sensor at a time and hit any Accessory (brake, hazard, turn signal ect.) The culprit is the CAS (cam angle sensor).

When key is on position:
I plug the sensor in, the pump primes.
I unplug the sensor, the pump primes.
I plug the sensor in, and hit Accessory pump primes
I unplug the sensor, and hit Accessory pump DOES NOT prime.

IM SO DAMN CONFUSED!!!
I did all the calibrations and uploaded the base maps. My sister took the laptop right when i needed it. So i havent had the chance to check anything in the AEM program that may cause this problem. Im going to check the program tommarow and see if there is any setting that i screwed with.

INFO:
I am running my MAP sensor off my MAF wiring.
I am running an AIT sensor.
I repinned them to the correct locations (MAP is pin 35, AIT is pin 26)
I currently just relocated those pins back to their stock locations and see if the problem persisted (It did)
When I plug my stock ECU in, there is no problem at all. Even with MAP AND AIT sensors pinned in correct locations and also pinned back to stock.
With MAP and AIT sensors pinned to correct locations (AEM pinout) I have started the car and it did idle.

Please help me out. YES i did talk to AEM technician and he helped me out finding the weird CAS situation (process of elimination of sensors) but couldn't pin the exact problem. All he said was to check my wiring (Which i didnt touch during my build except for MAP and AIT wiring)

steve shadows

Check your battery are wiring, i.e. your engine swap wiring and make sure that you still have the ECCS Relay WIRE contiguous on both sides

It is a RED thin wire with a BLACK STRIPE

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sl87

Yep its still there. Funny you mention that because everytime i play with that wire on the EMS, with the key on the on position I can hear it clicking on the EGI relay and that relay gets warm to the touch. Also it activates the fuel pump to prime when it clicks. But I think its in conjuction with all the other accessories (brake, hazards, turn signal, radio) when activated.

Ive been doing some more research and Im going to check the wiring under the fuse/relay box on the passenger side of the engine bay to see if anything is crossed. I just remembered that I did take that box off before to move it out of the way, but never touched any of the wires.

sl87

I wanna blow up my car!!
I hook up the laptop to the EMS, now sometimes the pump will pump more than once. Two to three times sometimes. I tried looking around the AEM program to see if i could find something
Sometimes it wont stop priming till I unplug the CAS.
HELP!!

THE_FUGITIVE

Same problem here and its killing me to know why

Simon_Ru

This is just an electrical noise through power supply lines of AEM to the CAS signal lines. Absolutely normal behavior for both v1 and v2 Series.

In the v2 series, you can slightly coarse the sensitivity of the crankshaft channel with the settings, but this will not help much.