Fuel pressure fluctuating

[streakybacon]

Hi, having a fuel pressure problem here that has me stumped. New s14 sr20det swap into my s14. I have tried multiple fuel pressure regulators all with the same problem. When I try to adjust fuel pressure to 3 bar, it fluctuates pretty wildly. I have and in-line pressure gauge that shows pressure steady at around 20psi. It is also steady when it is too high, say 60psi. But when I adjust it close to 43, it starts jumping around. My only idea now is fuel pump, but I don't understand why it is steady at 60 but not 43. Video of me priming the pump, car not running: SEZDvpai3qw

Any ideas?

[cotbu]

Assuming your fuel feed and return lines are correctly connected to the rail?!?
The the inline gauge should be on the feed side after the fuel filter. my preference.

SO, check the pressure on the other line...., and normally the return line on the fpr is at the bottom so switch those around see what happens

[streakybacon]

Should have mentioned that. At first I did have the regulator on the wrong side of the rail, felt pretty dumb for that one. I have the regulator on the return side of the rail now, and have swapped feed and return lines on the regulator just in case. Have had a gauge on both lines to make sure I wasn't making another mistake. Also rewired the fuel pump (walbro 255) while I was out of ideas.

[sr20sean]

set it to 4 bar (58psi) then retune it?

[streakybacon]

That would be a good workaround, and I do plan on installing some larger injectors and tuning at 4 bar eventually. Just on a budget right now, so I was hoping to fix without too much extra. At the very least I want to understand why it's doing this, I'm just confused.

[eclipse_dsm]

Looks like you got the fuel lines on the FPR backwards.. Your line going coming from the gauge should be on the side of the FPR and the bottom port would be return to the tank "typically".

[S14DB]

Looks like you got the fuel lines on the FPR backwards.. Your line going coming from the gauge should be on the side of the FPR and the bottom port would be return to the tank "typically".

:stupid:

The fuel is leaking past the valve backwards creating the spikes.

Can you even get the car to start?

[eclipse_dsm]

Actually since its backwards and fuel is actually being blocked by the FPR. Fuel pressure will spike to max on what the FP will push and eventually trigger the cutoff switch turning off the pump to protect itself.

[streakybacon]

Wow, I feel dumb. I had tried it that way originally, but I must not have adjusted it enough. Tried it again today and adjusted it a lot further, and it is adjusted properly. Fuel pressure is working perfectly now, just an issue that seems like MAF now. Thanks for making me reconsider how I hooked it up, that'll teach me to think I know what I'm doing.