fuel return regulator question

[crrider80]

Hi guys. I've tried searching about this subject but couldn't find anything. I took off the little cap for the fuel return regulator and the little screw was screwed all the way in. This means the reagulator is wide open correct? What is the proper setting on this? I'm upgrading to a mk4 fuel pump, AFPR and 550's so what would be the best setting on the return regulator? Thanks
-Steve

 

[jetjock]

Not regulator, pulsation damper. It's on the supply line. Screw means nothing other than a way to tell if fuel pressure is present in the rail.

 

[crrider80]

Not regulator, pulsation damper. It's on the supply line. Screw means nothing other than a way to tell if fuel pressure is present in the rail.

oh, ok. Thanks. Figures why i didn't get the results i wanted in my search. So how should i have this screw set?
-Steve

 

[Kristian_Wraae]

What does the small screw do? Should it be all the way in?

I can't find anything about it in the TSRM.

 

[92TealSupra]

What does the small screw do? Should it be all the way in?

I can't find anything about it in the TSRM.

I have looked at mine and all have always been screwed in all the way. I am looking in the TSRM right now and I can't find anything.

 

[Kristian_Wraae]

Mine was two turns from all the way in.

 

[92TealSupra]

Mine was two turns from all the way in.

The one I have in my hand is turned all the way in, I could run out to my car and check really quick though, it doesn't look like anyone ever opened the hood on that car besides oil changes.

 

[jdub]

I have looked at mine and all have always been screwed in all the way. I am looking in the TSRM right now and I can't find anything.

The one I have in my hand is turned all the way in, I could run out to my car and check really quick though, it doesn't look like anyone ever opened the hood on that car besides oil changes.

Is there an echo in this thread or are we in the "Office of Redundancy"?


I have 5 of the fuel pulsation dampers laying around and checked all of them. The screws were 1-2 turns from fully tightened down on every one, but this is relative.

Think of the pulsation damper as a pressure shock absorber. Inside there is a spring on top of a diaphragm secured by the cap...the screw is secured to the spring at about mid distance. Here's a couple pics:

The screw indicates fuel pressure (like JJ said)...it pops up, and it also will increase/decrease response time.

 

[ForcedTorque]

Screw means nothing other than a way to tell if fuel pressure is present in the rail.

Did this get lost in here? Go buy a Fuel Pressure Regulator! Aeromotive makes a nice rising rate regulator like you need with your turbo car. Or, you could go cheap (not recommended) and buy one from ebay.

Fuel System + Cheap = BOOM

 

[jetjock]

Well, technically speaking it does do something but nothing that will effect how the engine runs. It's used to adjust the pressure response of the damper. To set it correctly requires a fast acting pressure sensor but you won't notice anything no matter where it is. I've seen more than a couple of cars with it missing. In theory having it wrong (or removing the damper entirely) could impact injector life and make fuel control less precise but I'm splitting hairs. If you're so anal as to be worried about that just set it a couple of turns out...

 

[jetjock]

What Jdub said. Know what hydraulic hammer is? Like when the pipes in an old house bang when a faucet is suddenly shut off? That's what happens in the fuel system each time an injector snaps closed. The fuel rail (as a reservoir) and pulsation damper act to smooth those spikes out. Tightening the screw down pulls the diaphragm up tight, limiting it's movement.

 

[gofastgeorge]

Just a side note.....

These are the No. 1 cause of engine fires on RX-7s, and probably a few Supras.

They are all 18+ years old, and can suffer from a ruptured diaphragm.
When they do, they spray fuel all over the engine bay.

I took mine off, and have seen no ill effects.
But you could always just pick up a new one from Toyota, and be safe.

 

[jdub]

Tightening the screw down pulls the diaphragm up tight, limiting it's movement.

To add, if you tighten all the way down, you might as well remove it IMO. It's not doing a whole lot of good at that position.

 

[ForcedTorque]

I'm upgrading to a mk4 fuel pump, AFPR and 550's so what would be the best setting on the return regulator? Thanks
-Steve

I think you'd be better served to drill out, or bypass the J-Tube to compensate for the increased pressure. If my limited mechanical knowledge serves me correctly, the AFPR is on the return side.

Is there an echo in this thread or are we in the "Office of Redundancy"?


I have 5 of the fuel pulsation dampers laying around and checked all of them. The screws were 1-2 turns from fully tightened down on every one, but this is relative.

Think of the pulsation damper as a pressure shock absorber. Inside there is a spring on top of a diaphragm secured by the cap...the screw is secured to the spring at about mid distance. Here's a couple pics:

The screw indicates fuel pressure (like JJ said)...it pops up, and it also will increase/decrease response time.

Well, technically speaking it does do something but nothing that will effect how the engine runs. It's used to adjust the pressure response of the damper. To set it correctly requires a fast acting pressure sensor but you won't notice anything no matter where it is. I've seen more than a couple of cars with it missing. In theory having it wrong (or removing the damper entirely) could impact injector life and make fuel control less precise but I'm splitting hairs. If you're so anal as to be worried about that just set it a couple of turns out...

Good info guys! The above bolded line leads me to believe I will not be touching mine.

 

[jdub]

I think you'd be better served to drill out, or bypass the J-Tube to compensate for the increased pressure. If my limited mechanical knowledge serves me correctly, the AFPR is on the return side.

With a higher pressure pump, you want to drill the J-tube and you will need an AFPR. The stock restriction is there to serve as a back-up to a failed FPR. With a higher pressure pump, the restriction will limit the flow return to the tank and make adjustments to FP on the low side difficult if not impossible.

Your knowledge, in fact, serves you correctly

 

[cinciguy89turbo]

if the FPR malfunctioning is not right will it make the car seem like its laboring and weighs 6 tons under hard acceleration?