I have a 1990 miata 5spd and I installed a fuel pressure regulator and yet it won't read any pressure. Which line should I connect to the FPR? There is a line that comes from the bottom of the stock FPR and that's where I've tapped off into the AFPR and then from there to the metal line that is on the top. I 've adjusted the screw and yet nothing happens. What gives?

 

Where are you reading fuel pressure from?

 

On the FPR gauge.

 

does it read any pressure?

 

none at all. I think I might have purchased an FMU as opposed to a FPR

 

courtesy of braineack

 

if it doesn't read any pressure, it means you hooked it up right....techincally. becuase the return line should be void of pressure behind the FPR, once you get into boost and the FMU clamps down it should see some.

 

Thank you much everyone....This diagram is exactly what I needed. I guess my FPR is the type that is boost activated.....It does not look like a traditional FMU....I will get a pressure gauge and attach it to the fuel line. Still not sure why the guage on the FPR is not working though.
In fact do I even need a FPR or FMU if I'm only going to boost 5psi with 315cc injectors? I've already have installed a Walboro 255 pump.

 

With 5 psi, that is about 150 to 160 hp. Using the calculations in the DIY sticky, that means you need about a 290cc injector. Since you have 315cc's there is no need for an FPR, just watch your A/F.

If it is a boost dependant FPR, then it needs to be hooked upto a vac line too. Take a picture of it, and well tell you what FPR you have.

 

 

 

 

I have no clue what you have there...

 

that FPR looks to be a replace for a stock unit.....

 

you must delete the stock fpr in order to use this unit!!!... an fmu looks like a ufo and raises fuel based on boost pressures...the fpr on the other hand kinda does the same but not in a ratio like begi afpr/fmu or tradition vortec/obx fmu's...

 

I have the same unit. How did it turn out? Any pictures of the finished product?