Understanding Adjustable Fuel Pressure Regulator

[bdeliman]

I want to make sure I understand how the adjustable fuel pressure regulator works before I swap out what may be a malfunctioning part. Am I correct in assuming that the fuel pressure regulator should increase the fuel pressure by the boost pressure? I have 42 psi of fuel pressure at idle with the vacume line off. At 20 lbs of boost, I am reading 58 psi fuel pressure, when I think I should have 42 + 20 = 62 psi. This may be contributing to a large O2 correction to maintain the 11.5/1 air to fuel ratio. Am I correct, or am I missing something. Thanks in advance.

 

[Jerryl]

I want to make sure I understand how the adjustable fuel pressure regulator works before I swap out what may be a malfunctioning part. Am I correct in assuming that the fuel pressure regulator should increase the fuel pressure by the boost pressure? I have 42 psi of fuel pressure at idle with the vacume line off. At 20 lbs of boost, I am reading 58 psi fuel pressure, when I think I should have 42 + 20 = 62 psi. This may be contributing to a large O2 correction to maintain the 11.5/1 air to fuel ratio. Am I correct, or am I missing something. Thanks in advance.

You are correct.

Just went to a verification process as well.
There are a few things that come into play when FP is a bit lower than expected;
- Leaking boost @ signal line
- Weak fuel pump
- Plugged filter / Pump sock
- Kinked defective feed line
- Low Voltage
- Calibration variance between boost and FP gauge
- Reading error (Unless you are logging)
- Defective FPR
- Low fuel level

 

[XLR8]

You are correct on the FP increasing pound for pound with boost. I would guess, however, that it is something other than the regulator causing your issue. What fuel pump do you have now? Is it hot-wired? If you have a good hot-wired pump, I would start by changing the fuel filter. When I had an issue similar to yours it was a clogged fuel sock.

 

[bdeliman]

Fuel Pressure

Thanks guys. I have to check the filter. I have a Walbro fuel pump, with a hotwire kit and new line from the filter to the rail.