HPFP Pressure low after upgrade

[Kay2thePea]

So I just had my HPFP apart to upgrade the internals and rebuild it by changing all o-rings, and at the same time I upgraded the intake to a corksport 3" power series. I updated the MAF calibration to the calibration info that corksport provides for this intake. the hpfp did give me a bit of a hassle with the spill valve being somewhat seized up, but soaking it in some seafoam for half hour allowed it to move inside of the threaded housing and i was able to push the center out and change the o ring and get everything back together. i was really careful with the whole valve, cleaning everything really well but also being damn sure everything went back together properly and correctly. screwed the spill valve back into the hpfp lightly, reinstalled the hpfp onto the engine, then poured a bit of seafoam into the spill valve and then snugged it back up very lightly. restarted and saw the hpfp presssure was super low (like under 100), went out and snugged the spill valve up a bit more and the pressure came back up to around 350 psi or so. but as the engine ran, the pressure came back down to a bit under 200. when i rev up the engine a little it does come up over 500, but it defintely does not come up NEARLY as high as the factory internals did (i upgraded the internals to the corksport interals kit). Now it doesn't go above about 800 psi!!!

please help! logs attached for a short drive, you can see the hpfp pressure does drop, and causes knock near the very end of this short drive once.

[mituc]

Well, pull it back and take it apart, since you redid everything it's hart to tell what went wrong. Not exceeding 600PSI of fuel pressure is far from ideal.
P.S.: do you have the check engine light on? If so, what PIDs? Any fuel regulator related codes?

[Kay2thePea]

well i figured out the issue. i had not tightened the spill valve enough. i had read on another forum that you only want to tighten it a little more than hand tight, so i did that, and had issues. i looked over everything else, actually pulled it apart and rebuilt the hpfp again because i had not really used the correct stuff to clean and lubricate it when i did it the first time (first time i had seafoam engine treatment which i used as lubricant, which technically should be lubricating, but isn't hte same as redline fuel injector cleaner which is apparently the most recommended lubricant and which is what i used for the second go around), for cleaning the first time i had used chlorinated brake cleaner which i later found out can leave a slight residue which can somehow react in the hpfp and contribute to the "black death" gunk buildup issue some people have with them, especially when engine oil is used to lubricate the hpfp in any way as well (which Cobb recommends in their instructions, and which i did use for a couple of things particularly o-rings because i was following their instructions).

So yeah i redid it by using naptha (lighter fluid with no additives) to clean everything, and then i lubricated every part LIBERALLY with Redline Fuel Injector Cleaner (I think it's SM1 but i may be mistaken there? SD1? Not sure lol) and reassembled everything, but still had issues though the issues weren't as bad.

So as kind of a hail mary, i grabbed my big crescent wrench and gave the spill valve another 1/16th of a turn or so, just a nudge, and while I was doing that, I had OBD fusion opened on my phone beside me so I could watch all of the engine parameters (the engine was idling when i did this). Immediately as soon as I tightened the spill valve up like that, it went from around 200psi up to about 300psi. BOOM! I was onto something. So I snugged her up a little more, and once more again, and there we are, I'm now at 430psi at idle. Happy day!

[mituc]

Hand tight? I'm not sure on what forum you've read that, but you should remember how it was tightened when you took it off and take that as a point of reference. It takes a vice and a lot of force applied to a 30cm wrench, that's a little more than just hand tight...