So, I was having a bucking/stuttering problem on the top end/peak torque of my road dyno pulls. This was not mild at all, it was violent and felt like fuel cut.
I narrowed it down to the 460 pump I installed during my motor build. Let me tell you what I personally found to solve the problems I was having so that you too may take this into consideration when installing one of these awesome pumps.
The initial way I had this setup was by using the stock hanger setup and the stock wiring. This did not work at all. Every WOT run I would do ended in a bucking stuttering fuel cut and letting off the accelerator.
Thinking that it was a power issue I ran a #10 wire and a #10 ground. I ran the power to a 30 amp relay, used the original power/ground that went to the stock fuel pump to power the coil in the relay, and ran the #10 ground directly to the pump itself. Took it out for a drive and had the same problems. I was now thinking I had a bad fuel pump. I started searching the internet for answers and came across numerous threads with blown fuel pump controllers/electronics when using a walbro 400/460 pump.
The reason the fuel pump controllers were burning up was from the simple fact that if the body of the fuel pump makes contact with the hanger or any other type of ground the fuel pump controller cannot use PWM on the ground wire from the ecu to control the flow of the pump (33%,66% or 100%). The walbro 460/400 pumps have an internal connection from the wiring ground to the body of the pump. Most other pumps do not have this or they fit into the hanger so that no contact from the hanger induces a faulty ground signal sent back to the ecu for controlling the flow of the fuel pump. Also keep in mind that the 460 pump will pull a whopping 19 amps @13.5 volts and 80 psi. The stock fuel pump controller is not up to this task at all.
This is what I did to eliminate the problem 100%. I removed the fuel pump controller in its entirety. I disabled the p0230 FUEL PUMP CONTROLLER code from the ecu. I then took the harness that goes from the passenger side of the trunk and made a jumper wire from the stock fuel pump relay that normally powers the fuel pump controller (black yellow wire) to the original fuel pump power wire (black orange wire). I made a good solid ground in the trunk and connected that to the original fuel pumps ground wire (black white wire). These jumpers would now end up turning the 30 amp relay on/off when the ignition is turned on. The pump will run at 100% all of the time now so I recommend an aftermarket FPR. I am running a sard unit and it is working flawless for me.
I chased my tail for 2 weeks trying to figure this out. The 2005 STI pulls hard all the way to redline now and I can maintain an afr of 10.5-1 if I would like. Learn from my mistakes, the stock fuel pump controller does not provide the means to control this pump without issues unless rewired or eliminated from the equation.
I narrowed it down to the 460 pump I installed during my motor build. Let me tell you what I personally found to solve the problems I was having so that you too may take this into consideration when installing one of these awesome pumps.
The initial way I had this setup was by using the stock hanger setup and the stock wiring. This did not work at all. Every WOT run I would do ended in a bucking stuttering fuel cut and letting off the accelerator.
Thinking that it was a power issue I ran a #10 wire and a #10 ground. I ran the power to a 30 amp relay, used the original power/ground that went to the stock fuel pump to power the coil in the relay, and ran the #10 ground directly to the pump itself. Took it out for a drive and had the same problems. I was now thinking I had a bad fuel pump. I started searching the internet for answers and came across numerous threads with blown fuel pump controllers/electronics when using a walbro 400/460 pump.
The reason the fuel pump controllers were burning up was from the simple fact that if the body of the fuel pump makes contact with the hanger or any other type of ground the fuel pump controller cannot use PWM on the ground wire from the ecu to control the flow of the pump (33%,66% or 100%). The walbro 460/400 pumps have an internal connection from the wiring ground to the body of the pump. Most other pumps do not have this or they fit into the hanger so that no contact from the hanger induces a faulty ground signal sent back to the ecu for controlling the flow of the fuel pump. Also keep in mind that the 460 pump will pull a whopping 19 amps @13.5 volts and 80 psi. The stock fuel pump controller is not up to this task at all.
This is what I did to eliminate the problem 100%. I removed the fuel pump controller in its entirety. I disabled the p0230 FUEL PUMP CONTROLLER code from the ecu. I then took the harness that goes from the passenger side of the trunk and made a jumper wire from the stock fuel pump relay that normally powers the fuel pump controller (black yellow wire) to the original fuel pump power wire (black orange wire). I made a good solid ground in the trunk and connected that to the original fuel pumps ground wire (black white wire). These jumpers would now end up turning the 30 amp relay on/off when the ignition is turned on. The pump will run at 100% all of the time now so I recommend an aftermarket FPR. I am running a sard unit and it is working flawless for me.
I chased my tail for 2 weeks trying to figure this out. The 2005 STI pulls hard all the way to redline now and I can maintain an afr of 10.5-1 if I would like. Learn from my mistakes, the stock fuel pump controller does not provide the means to control this pump without issues unless rewired or eliminated from the equation.
