Hello all. I have a s4 t2, that is having some issues turning on the fuel pump. While I installed the new engine I wired up the fuel pump strait to the battery (with a switch and a fuse) to get it to come on. The car had a stand alone, but now it is back to stock ECU.

The pump turns on when I had it going strait to the battery so I know it works. I installed and replaced the fuel relay, that works, it clicks. But I am still not getting any power back to the pump.

Any ideas?

Thanks
~Tweak

 

check ground.

 

I did. I checked it 12 volts was even going to the pump at the connector and it isnt. (with my DMM) So somewhere between the pump and ... the battery .. something isn't working. The relay under the dash is clicking, so I assume that is working. I guess I will have to see if power is going to that or not. Is there anything else before or after the relay I should check?

thanks.

 

that right there, is your mistake. assuming will get you no where, fast. I have made these mistakes before too.

 

well I changed two of them out. hehe but yes, I will have to see if power is getting to it or not. I will have to wait till tomorrow though.

 

good luck

 

thank you.

 

So wait... you are trying to get the fuel pump working through a relatively stock configuration? There should be a signal coming from the circuit opening relay (under the dash) to the connector at the back of the car. The circuit opening relay needs a ground from the AFM when the car is turning over in order to send the signal to the fuel pump. Is it getting that? The fuel pump check connector can also supply this ground instead.

What happened to your resistor relay? Did you cut it out? There are two sets of blue wires that connect to the stock resistor relay under the hood. Those need to be jumpered together if you are bypassing the resistor relay completely.

Try to look at the FSM wiring diagrams (FSM page 50-25 , 50-34), fuel and emissions control section. I found that reading the pages at the beginning helps immensely with understanding what all the symbols mean.

 

page 50-34 is what you need to look at. First jumper the fuel pump check connector and see if juice is coming from the light blue/Red wire on the circuit opening relay (COR). If that isn't working, you've most likely got some kind of messed up wiring somewhere preventing that ground (brown wire) from getting to the COR.

If juice is coming out of the light blue/Red wire, check under the hood at the stock resistor relay location on the passenger fenderwall area not far from the headlight. If you look at the wiring diagram you will see that there are two L/R wires that connect to respective L wires. They need to be connected together if you have eliminated the resistor relay. From there the signal goes to the fuel pump itself. If somebody relocated the resistor relay (rather than bypassing it) you've got a mess on your hands...

 

wow awesome. Thank you very much, I am going to go out and test that right now. Someday soon, I would like to talk to you about your t04s also.

Update: Ok, good news, (I think) I am getting 10.9ish volts out of the blue wire that cames out of the relay under the dash. So somewhere between that and the fuel pump something is missing or broken. I am going to check for the one on the passenger fenderwall area.

 

ok, I see what he did. He cut the wires to the resistor relay. I touched them back together, and the fuel pump started! Wow, thank you very much for all the help. Doing this standalone back to stock ECU car has taught me so much. O.o

Again thank you, now off to fix my stumble problem when my pedal is only 1/8th in.

 

shoot me a PM if you've got more questions.

I went through that whole fuel pump wiring mess. I cut out my resistor relay which, the previous owner had relocated, because I think it went bad. So I had to make sense out of all the fuel pump wires. I bet not having it doesn't make much of a difference on a stock car anyway. I had an FD fuel pump in my nonturbo (which had no resistor relay from the factory) and I didn't notice driveability problems.

https://www.rx7club.com/2nd-generation-specific-1986-1992-17/pics-my-overkill-fuel-pump-rewire-732904/