2018 civic si fuel pressure issue

[Blizzyk02]

So my buddy blew his motor sent it off got a full rebuild with forged internals so we are ready to make some power.

While the car was gone he had them do a hpfp and LPFP and injectors. Now the car is back we get it on the dyno with a base map do a pull and get p0087 low pressure at the rail.

so we assume the issue is the pump or fuel regulator, after putting a new pump in 3 times a new factory pump, a dw300 and a hondata pump with a new regulator none worked and did the above in the video.

as you can see at about 4k rpm while doing a pull when the target and actual are 19k the target rises and the actual begins to drop. We even tried our original tune which ran great with factory motor and full prl turbo kit for 50k miles but now with the same setup just built motor and better fuel setup won’t work.

if anyone has any ideas I’m open to anything thank you for the help ahead of time.

 

[cota]

There's a couple factors. The fact that you replaced the lpfp with 3 different products and all producing the same result, i'm certain that the lpfp is NOT the problem. If the lpfp was bad, more than likely the car would barely run. Hpfp or something along those lines is likely the culprit. My theory is supported by an issue I ran into myself on my 10th gen si, see below.

I had p0087 issue twice in 2 months: 1st time, the issue was the hpfp going out, car was drivable, but limp mode and couldn't get past 50 mph. 2nd time, couldn't even start the car due to lpfp o-ring broke off and not getting any fuel from the fuel tank into the rest of the fuel system.

Keep me updated

 

[Blizzyk02]

There's a couple factors. The fact that you replaced the lpfp with 3 different products and all producing the same result, i'm certain that the lpfp is NOT the problem. If the lpfp was bad, more than likely the car would barely run. Hpfp or something along those lines is likely the culprit. My theory is supported by an issue I ran into myself on my 10th gen si, see below.

I had p0087 issue twice in 2 months: 1st time, the issue was the hpfp going out, car was drivable, but limp mode and couldn't get past 50 mph. 2nd time, couldn't even start the car due to lpfp o-ring broke off and not getting any fuel from the fuel tank into the rest of the fuel system.

Keep me updated

Ok thank you so maybe I check the hpfp next any tips on how u can go about that

 

[Blizzyk02]

There's a couple factors. The fact that you replaced the lpfp with 3 different products and all producing the same result, i'm certain that the lpfp is NOT the problem. If the lpfp was bad, more than likely the car would barely run. Hpfp or something along those lines is likely the culprit. My theory is supported by an issue I ran into myself on my 10th gen si, see below.

I had p0087 issue twice in 2 months: 1st time, the issue was the hpfp going out, car was drivable, but limp mode and couldn't get past 50 mph. 2nd time, couldn't even start the car due to lpfp o-ring broke off and not getting any fuel from the fuel tank into the rest of the fuel system.

Keep me updated

Also I’ve driven the car my self gears 1-2 you can run to limiter gear 3 at 6k gives you an engine light from the drop of pressure over the pull and same thing in 4th

 

[cota]

Ok thank you so maybe I check the hpfp next any tips on how u can go about that

no idea other than having it replaced. i think it's abt $300 for oem hpfp. labor was about $100 and 30-45 mins when my local swapped it

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