I recently had issues with my car stalling/stuttering so I decided to do 12V fuel pump mod (bypass fuel pump ECU) and car ran like a champ. Then a month after that I had issues getting the car to start up but after multiple attempts the car started up and drove fine. But one morning I went to drive it and the car would crank over and over but no start. My first thought was that the old fuel pump died out since it was getting full 12V and was maybe on its last legs. So I bought a new fuel pump installed and still same issue. I did not hear the fuel pump turning on at all so I tried swapping the EFI relay and still nothing. So then I tried jumping FP and B+ then try starting and nada. Once more I still have not heard fuel pump turn on at any point. So then I tested with multimeter and I do not get any power to FP or +B at all. So then I tried checking power to the wires I crimped together for the 12V fuel pump mod (green and black/red wires) and still no power with key in ON position. I also made sure the main fuse box was getting sufficient power.

Sooooo I am stumped. Is there anything I can test out to see why I am not getting power to fuel pump? I'm not sure if I can test the actual power source of the EFI relay itself or does jumping the FP and B+ bypass the relay?

Thanks guys!

 

I guess im going to try a toggle switch from the battery to fuel pump and check to see if that work for now. Not sure what else to test at this time. Any input would be appreciated.

 

If you get tired of the fuel ECU like I did, get a SPST relay and use the antenna switched 12v wire in the trunk as a turn-on for the relay.

Fuel pump on when key turned, fuel pump off otherwise. Simple. No guessing.

 

Just noticed CEL light is not turning on either when key is on the ON position. Must be related....

 

similar problem wit my 03 es300. I've checked with a tester that can send power that the grounds to FP are good, hot line on the fuel pump(blue) is not receiving power. Even sprayed starter fluid directly and jumped it to another running car and it worked but then died out again. Changed cam sensor, plugs, even checked compression. Im getting spark I checked at each coil. Not getting a security light tho...but it feels like it could be that simple. Did get a code, P0348. which is why I did so many checks and changes. Tested voltage and ground at relays too and all fuses. Should reset the ECU?