Mr-C Posted October 29, 2018 Share Posted October 29, 2018 Hey gang, I've been chasing a Lean condition and thinking now its related to my FPR. I just installed a Glow Shift in-line fuel pressure gauge (on the feed line) and PSI is stuck at around 30psi at idle with and without the FPR vaccuum line removed, which in both cases is under spec per the FSM. Revving the engine to 2000 rpm doesn't change anything either. Any further test I should do.....such as pinching the return line to see is psi increase? If its a faulty FPR should I replace with the original or go with the 07' older STI "mod" i've been reading here? *Note: I have stock injectors which passed flow bench testing and a new DW65 fuel pump and gas filter which has all been installed 5 months ago. Thanks, Link to comment Share on other sites More sharing options...
ehsnils Posted October 29, 2018 Share Posted October 29, 2018 Bad fuel pressure - first item that should be checked is the pump. Pressure regulator is second to check. But make sure that any gauge used is calibrated or at least compared with a known good gauge so you now how much off the gauge is from actual values. Otherwise you may be on a wild goose chase hunting the wrong problem. Link to comment Share on other sites More sharing options...
Mr-C Posted October 29, 2018 Author Share Posted October 29, 2018 Bad fuel pressure - first item that should be checked is the pump. Pressure regulator is second to check. But make sure that any gauge used is calibrated or at least compared with a known good gauge so you now how much off the gauge is from actual values. Otherwise you may be on a wild goose chase hunting the wrong problem. Right, I'm thinking of putting back the OEM pump and check again. However even if the gauge was %1-2 off in readings, shouldn't it still spike in psi when I remove the fpr vacuum hose? Thanks, Link to comment Share on other sites More sharing options...
m sprank Posted October 29, 2018 Share Posted October 29, 2018 Fuel pressure with no reference to vacuum should be 43.5psi. When reference to vacuum is applied pressure should drop (linear) with vacuum and rise (linear) with boost. Link to comment Share on other sites More sharing options...
Mr-C Posted October 29, 2018 Author Share Posted October 29, 2018 Fuel pressure with no reference to vacuum should be 43.5psi. When reference to vacuum is applied pressure should drop (linear) with vacuum and rise (linear) with boost. Yea none of that is happening. Link to comment Share on other sites More sharing options...
m sprank Posted October 29, 2018 Share Posted October 29, 2018 FPR, pump, restriction in line. If low all the time, that is usually how the DW65c dies. When an FPR dies they tend to over pressurize at start up causing misfires or no go. Link to comment Share on other sites More sharing options...
Mr-C Posted October 29, 2018 Author Share Posted October 29, 2018 FPR, pump, restriction in line. If low all the time, that is usually how the DW65c dies. When an FPR dies they tend to over pressurize at start up causing misfires or no go. Ok, So first change the pump and see what happens.....thanks! The DW65 is brand new and sure it has 3yr warranty but should I even consider replacing it with another? Is there any other "plug n play" solution? Link to comment Share on other sites More sharing options...
m sprank Posted October 29, 2018 Share Posted October 29, 2018 If you like DW the 300c has better reliability than the 65c. Many on this forum run the AEM pumps. Link to comment Share on other sites More sharing options...
Dishwasher Posted October 29, 2018 Share Posted October 29, 2018 Replaced my 65c with an AEM 320 and: http://www.viciousink.net/wp-content/uploads/2018/01/No-Regerts-Arm-Tattoo-Fail-768x403.jpg Brought to you by Pfizer Link to comment Share on other sites More sharing options...
Tronic Posted October 30, 2018 Share Posted October 30, 2018 Sorry is it a turbo or a N/A engine ? 30psi is okay with the vac line connected but the pressure should still rise when you disconnect the vac line. With a Turbo the FPR is like a 1:1 rising rate with boost so if you connect a hose to the FPR and use a syringe to provide pressure, you will probably see 50psi if the pump and FPR are working correctly. Personally my fuel pressure gauge is cabin mounted in one of my cars. Very useful to verify both the FPR and pump as you drive. You will blow a turbo engine pretty quickly running lean. Link to comment Share on other sites More sharing options...
Mr-C Posted October 30, 2018 Author Share Posted October 30, 2018 Sorry is it a turbo or a N/A engine ? 30psi is okay with the vac line connected but the pressure should still rise when you disconnect the vac line. With a Turbo the FPR is like a 1:1 rising rate with boost so if you connect a hose to the FPR and use a syringe to provide pressure, you will probably see 50psi if the pump and FPR are working correctly. Personally my fuel pressure gauge is cabin mounted in one of my cars. Very useful to verify both the FPR and pump as you drive. You will blow a turbo engine pretty quickly running lean. Hi, My car is a turbo (2005), are you saying to test the fpr by adding the vacuum line to a syringe and applying pressure while the car is at idle? Thanks, Link to comment Share on other sites More sharing options...
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