Fuel Pressure regulators explained

[yellerandahalf]

I've seen a few things recently involving confusion about FPR's, so I thought I'd share what I've picked up from working as a mechanic for a few years now.

There are 5 main types of regulators.
1)non-adjustable static: does not see intake pressure, can't be adjusted by the user
2)non-adjustable increasing: user can't adjust it, but it DOES change pressure due to manifold pressure. Some stock regs are like this.

*note* our stock regulators are one of the above. I think it is type 2, because it seems to be controlled by a circuit from the PCM.

3) adjustable static: adjust the pressure to what you want, and it stays there.
4) adjustable 1:1 rising. you adjust the base (idle) pressure, and then the regulator brings fuel pressure up with a 1:1 ratio with boost pressure.
5) adjustable rising rate (RRFPR or FMU). adjust your base pressure, and then the reg brings fuel up at a rate that rises with boost. You can also adjust how quickly it brings up fuel with boost.

Hope this helps, and feel free to correct/embellish.
-Mateo

 

[02MazPro5]

Thanks for the info on that. Here is a question though, the cheap regulators I see on e-bay all the time which one are they? are they the static adjustable or the 1:1 adjustable.

 

[zerocover]

If they have a vac line in there rising, as far as I can tell they do. So yeah 1:1 adjustable.

For reference were #2.

 

[yellerandahalf]

It's hard to say what kind of regulators are on ebay. I'd be willing to bet that you'd be able to find at least one of each kind every day on ebay. If it has a port for a vacuum line, it's either a 1:1 or rising rate (if it's aftermarket).
-Mateo