Super High Fuel pressure

[DD725]

Ok walbro fuel pump was installed about 4 months ago, line completely deteriorated inside the tank so another feed line from pump to sending unit was replaced. After replacing all damaged and dry rotted fuel lines, my fuel pressure to the rail is 90psi, ummm wtf I think thats a little high. I was unaware that I would need an AFPR in conjunction with the walbro fuel pump. Is that my only option, AFPR or can I dial it down some other way. Also I bought the vehicle with the NEO rb25det swap already done and the previous owner has an adjustment knob on the return side of the line. Question is, does the vehicle need a regulated return. and both damper and stock regulator are still being used.

[Darius]

It sounds like the FPR is also shot and restricting the return flow or your return line has blockage in it. You do not need to install a new FPR with a walbro.

[DD725]

Ok thats good to know, now what about the adjuster/adjustment block thats on the return line?? I will get a pic of it up here later but according to most ppl my fuel lines are backwards but I have the R34 service manual and my lines are on correctly, if i switch them the car doesn't run. I will get a pic up asap so you can see what im talking about.

[Darius]

Adjustment block? Yes, please post a picture.

[Bluefire]

What do you mean adjustment knob on the return line? That would mean it has an FPR. Fuel damper you can eliminate. I would change all rubber lines and blow out the hardlines and rail with some air. Also from past experience, I have seen an increase in fuel pressure running a walbro fuel pump with stock reg. IIRC fuel pressure would sit just above 50psi off vac.

[DD725]

no it literally has an adjustment block in line with the return like before the return line goes under the firewall, but I got it figured out, previous owner had a 300zx fuel pump on the car and i guess it wasnt enough so they installed this block to restrict pressure in the rail to i guess have more pressure but anyway i removed this restricter block and car is idling with 40 to 45 psi now and runs great. But i will still post pics of what they had on the car tonight when i get out of work.

[Darius]

I'm glad you worked it out. That adjustment block definitely didn't sound right. Running 90 psi base pressure is insane! I don't understand WTF some people are thinking.

[Carl H]

sounds like some good ol' backyard engineering.