Fuel Pump issues

[jdm_s14_zenki]

Originally Posted by g6civcx

Why are people telling him to jump the relay? If the relay is broken, fix it. If there is broken wiring, fix it. If the fuel pump is bad, replace it.

What benefits are there to having a pump that is permanently on with ignition power? The ECU needs to cut the fuel pump for a reason.

Quite frankly I'm really sick of seeing this topic pop up once a week. Maybe I'll just write a comprehensive fuel pump diagnostic thread and be done with it. Maybe

what he said. but ya, ive NEVER had a problem with my fuel pump wired to ignition. when i turn the key on, my fuel pump turns on. when i start the car, my fuel pumps on. when i step on the gas, the fuel pumps on. when i turn off the car, my fuel pumps OFF. cant be too complicated...why in the hell would the ecu need to shut off fuel? so you can go lean and detonate?

[g6civcx]

Originally Posted by jdm_s14_zenki

why in the hell would the ecu need to shut off fuel? so you can go lean and detonate?

I hear you on this, but you also have to balance this with the fact that any time you recommend a modification, you have to understand how the system as a whole will be affected. You have to look at how the wiring is done. It has to be clean, and provisions has to be made for safety.

The fuel pump circuitry sits on its own line. You need to clarify that if you piggyback it onto the existing ignition wiring, you have to look at the maximum load the system currently expects to support. Then you add in the maximum load the fuel pump is expected to draw. If the sum of the two max loads exceeds the max capacity of the ignition circuit, you're going to have problems.

So until you have addressed those questions, it's not good to say just piggyback the fuel pump onto the ignition system.

The best way to do that would be to use a relay and tap into the ignition system as a power source. Only a small current will be drawn to activate the relay, which draws a large current from a different circuit. This is how the stock system works.

And actually all you would need to do is take the wire that goes from the fuel pump relay to the ECU and slice it in half. Remove/tuck away the side that goes to the ECU. Ground the side that goes to the relay. Now the relay thinks that the ECU is always turning the pump on. Much easier and safer than trying to piggyback onto another circuit.