Brian3676 Posted October 6, 2014 Share Posted October 6, 2014 Anyone had there fuel pressure fluctuate around 10 psi or so? A little history: I have been trying to track down my AF learning and WOT AFR issue for months now. I thought MAF plug was bad, replaced and that did not fix anything. Then noticed sometimes my voltage was lower/higher, but I fixed that for the most part, and after further testing noticed that my voltages did not really change with my AF learning and WOT AFRs, so I eliminated that as something I thought could effect the sensor readings. Today: I finally caught my fuel pressure in the middle of one of my cars AF learning swings. It was down to 30-32 PSI at idle, I removed the vac line, and it went up to 42 PSI. From the FSM I should see 38psi at idle and around 48 with vac line removed. As a good note: when my pressure is at 38psi, my AF learning is perfect, as is my AFRs under WOT situations. I can drive around for a while with perfect fuel pressures and AF learning around -.78, then come home and leave a while later, and have 30-32psi, and as high as 8% AF learning. I tested my fuel pump voltages, and they do seem to be good. I am wondering if my fuel pressure regulator is bad, but not totally failed, its just "wigging" out and causing 10psi swings? Anyone had this before? Only other thing I can think of is if the pump is wigging out, but its only 1 year old DW 65c... Link to comment Share on other sites More sharing options...
Brian3676 Posted October 7, 2014 Author Share Posted October 7, 2014 Anyone? Link to comment Share on other sites More sharing options...
dustinsonger Posted October 7, 2014 Share Posted October 7, 2014 any other fuel mods? Link to comment Share on other sites More sharing options...
Brian3676 Posted October 7, 2014 Author Share Posted October 7, 2014 740 sidefeed injectors and DW 65c fuel pump, pump is powered straight from a relay, so no fuel pump controler, however the ground is still ran through the controller. I am considering replacing the controller....but was going to lean towards FPR first Link to comment Share on other sites More sharing options...
Heticor Posted October 7, 2014 Share Posted October 7, 2014 could be due to this: http://www.iwsti.com/forums/2-5-liter-litre-factory-motor/128053-dirty-fuel-filter-causing-car-run-lean.html Link to comment Share on other sites More sharing options...
Brian3676 Posted October 7, 2014 Author Share Posted October 7, 2014 Well, the lgt does not have a filter like that, it's built into the fuel pump housing I think. Also I could understand constant low pressure that being the cause, but with it fluctuating I am unsure Link to comment Share on other sites More sharing options...
Brian3676 Posted October 7, 2014 Author Share Posted October 7, 2014 Ahhh, I see, the filter comes in the new casing . $79 . I'LL Replace it this weekend . Link to comment Share on other sites More sharing options...
Heticor Posted October 7, 2014 Share Posted October 7, 2014 the part number are these: Fuel filter 42072AG140 O Ring 42025AG070 x 3 O Ring 42025AG080 And the t bag filter on the foot of the pump , it is not sold by Subaru, but Toyota has it 42025AG080, they are identical. here a Russian thread showing the procedure (use Google translate) http://www.drive2.ru/l/288230376152682908/ Link to comment Share on other sites More sharing options...
Brian3676 Posted October 10, 2014 Author Share Posted October 10, 2014 Well, installed a brand new oem filter and all new O rings today, dident help my fuel pressure even 1psi. Also installed a extra gauge I had to check the one I had, it's identical. 32 psi at idle, 42 with no vac. After that I installed a used but good fuel pump controller to make sure that was good. No change Guess I'll try new fuel pressure regulator unless someone's got another idea! Link to comment Share on other sites More sharing options...
Brian3676 Posted October 15, 2014 Author Share Posted October 15, 2014 Installed fuel pressure regulator. Pressure was perfect for a while, I got all exited it was fixed.....then it dropped again and started fluctuating :-( I guess only thing left is my DW 65c shit out after less than a year? I mean it still works, but maybe for some reason its tweaking out? Has been replaced: In tank filter and pump sock and all O rings Fuel pump control module Fuel pressure regulator (entire assembly not just regulator) Fuel pressure gauge (to make sure gauge was working) Link to comment Share on other sites More sharing options...
Gex Posted October 15, 2014 Share Posted October 15, 2014 You replace your surge tank to fuel tank gasket ever? With several pulls of the pump it can leak. Also may have clogged something in the dw65c pump by not running the filter sock on it. Link to comment Share on other sites More sharing options...
Brian3676 Posted October 15, 2014 Author Share Posted October 15, 2014 Surge tank to fuel tank gasket? Not sure what gasket that is...but I did replace every O ring in the fuel pump assembly yes, there is a total of 4. I have had the sock on the pump since day one of install, and I replaced it with a new one when I installed the new OEM Subaru in tank filter as well. Link to comment Share on other sites More sharing options...
Gex Posted October 15, 2014 Share Posted October 15, 2014 http://opposedforces.com/parts/legacy/us_b13/type_38/intake_and_supply_system_turbocharger/fuel_tank/illustration_2/ #23 gasket 42025AG04A Link to comment Share on other sites More sharing options...
Brian3676 Posted October 15, 2014 Author Share Posted October 15, 2014 Oh haha, that gasket, I was thinking of one that holds fuel pressure. Yes I replaced that the first time I installed the DW pump, and again last week when I did the filter and new O rings. Im not gunna risk leaking fuel over a $10 part. Thanks for verifying tho! Link to comment Share on other sites More sharing options...
Brian3676 Posted October 16, 2014 Author Share Posted October 16, 2014 Talked to DW today. He told me my issue could very well be the pump since I have replaced everything else. He also admitted that they did have some faulty pumps come in a while ago that have issues with varying amp draw and caused a symptom like I have, but assured me none of those pumps left there wear house. Said I can send it in for free and they will test it, but the wait is currently 2 weeks out..... Link to comment Share on other sites More sharing options...
Brian3676 Posted October 21, 2014 Author Share Posted October 21, 2014 Did a amp draw test as DW suggested. 5.3A at 33% (about 7.5v)and 38psi, 9.7A at 100% (about 13.5v) and 46psi. At 40psi and 13.5v they advertise 11.4A, and at 50psi they say 11.9. If I remember correctly less draw is fine, you just dont want more..... This test was done when I had the higher fuel pressure, now to wait for my lower fuel pressure issue to come up again and test the draw. Link to comment Share on other sites More sharing options...
Max Capacity Posted October 21, 2014 Share Posted October 21, 2014 Did you send those numbers to DW ? Are they normal values? 305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD). CHECK your oil, these cars use it. Engine Build - Click Here Link to comment Share on other sites More sharing options...
mikeyvt Posted April 6, 2017 Share Posted April 6, 2017 Bringing this back from the dead but did you ever get this figured out? Link to comment Share on other sites More sharing options...
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