Hello everyone,

After changing my fuel lines to ptfe. My car is creating a lean spot around 3.7k-4k rpm during WOT. The tuner is saying the tune is okay. He put many of the fuel on that rpm still it creats lean spot. During cruise, the car bogs on part throttle. The fuel pump hanger gets HOT after doing some of the pulls. The fuel pump also starts to make whining noise at the same time on idle. But the fuel pump sounds normal and idle afr is also okay during the cold start. After doing WOT, it messes up. The boost fuel pump was also dead few days back. So, i had an extra fuel pump. Now, my spare boost pump also disturbing, sometimes it turns on and sometimes it bogs when the second pump turns on. Could anyone help me out what should i look into and solve the problem? I've checked few things which are perfectly fine on the car:
No boost leak
No Vacuum leak
No fuel line leakage
Fpr working fine (38-39) with Vacuum and (43.5) without Vacuum
Fuel pump relay is also fine
All the fuse are also okay.

P.s. i did a small modification on the return line which is, i connect my ptfe fuel line with nylon fuel line which connects with the stock return line through connectors. Pictures attached above.

 

1. Fuel pressure regulator (FPR): While you mentioned that the FPR seems to be working fine, it's worth double-checking its functionality. Ensure that it is maintaining the correct fuel pressure throughout the entire RPM range, especially during WOT.

2. Fuel pump: The fact that your fuel pump hanger gets hot and the pump starts making a whining noise after WOT suggests that there may be an issue with the fuel pump itself. It could be struggling to deliver enough fuel at higher RPMs. Consider checking the fuel pump's voltage and current draw to ensure it is operating within the manufacturer's specifications.

3. Fuel pump wiring: Inspect the wiring and connections for the fuel pump to ensure they are secure and not causing any intermittent issues. Loose or damaged wiring can lead to inconsistent pump operation.

4. Fuel filter: A clogged or dirty fuel filter can restrict fuel flow and cause similar symptoms. Consider replacing the fuel filter if it hasn't been done recently.

5. ECU tune: While your tuner may have adjusted the fueling, it's possible that there could be an issue with the tune itself. Consider seeking a second opinion from another experienced tuner to ensure the tune is optimized for your specific modifications.

6. Fuel pressure dampener: Some Evo owners have reported issues with the fuel pressure dampener causing fueling problems. Consider inspecting and potentially replacing this component if necessary.