Hey all. has somebody had problem(s) with the fuel presure regulator,,,how does the engine/car act ?
this ****** pisses me off.......pos anyone ?

 

if the pressure regulator goes bad, your engine will get too much fuel and flood. i haven't had a problem with mine. hopefully it stays that way. it can also cause constant flooding.

 

the thing starts, runs for a second then dies. fuel presure is way low, brand new fuel pump too. i take some hyhmostats and crimp the return fuel line and the presure goes up, engine starts and then dies still.
it can't be the presure relay,,,can it ? and the fusable link for the re-egi how often do those die. i'm about to pull the injectors and test those next.

 

Very unlikely to be the fuel pressure regulator on the fuel rail. These work by using a vacuum signal attached to the 'rats nest' that tells the fuel pressure regulator when to unleash higher fuel pressure under heavy vacuum. When this occurs, the FPR opens, which increases fuel pressure in the fuel rail.

A fuel line that is occluded, crimped, or clogged, can cause fuel pressure to remain low in spite of a good fuel pump. Also, when you changed the pump, did you also replace the fuel filter? It looks like this, and is located in the same general area (in front of the rear axle):



The SE fuel filter is different than a standard, carb'ed, car, since it must handle a much higher volume of fuel, as well as higher pressure. Do not attempt to use a standard plastic filter or you'll blow it out and cause a serious fire hazard.

When you cut off the return line, this is likely bumping up your fuel pressure to over 45-50psi which is beyond the range that your injectors were designed to work. The standard pressures are about 35psi at idle, and about 40-45psi at WOT.

If you still can't keep it running when you block off the return, you may have a problem with the fuel injectors, themselves, or otherwise a fuel filtration or flow problem that's preventing the injectors from getting enough juice.

Even though this may look like a fuel issue, you might also be looking at a bad AFM or ignition component. Fuel pressure regulators and the fuel pulsation dampener are unlikely causes of the problems you describe.

Recently, I had 2 injectors sent off to RC Engineering for flow balancing, cleaning and leak testing, and when they came back, returned idle quality, fuel mileage and performance. I don't know of any tests you can do to your injectors unless you have the flow-testing bench equipment around your garage - I don't. HTH, at least a bit,

 

hey long duck,, good an -SE guy. check it out. to track down this problem i've done this so far. i've droped the gas tank,tryed with a -SE filter, and bypassed the filter.
get the same flow at the firewall.with the tank on the ground i've made the fuel system loop, i can hear gas returning in the tank, no leaks either.pulled the upper intake and everything that goes with it. and i'm looking at the delivery pipe (fuel rail). turn 'on' the key and open the 'flapper' door to engage the fuel pump. works fine. i can hear gas throught the top of the engine. no air leaks/gas leaks, pulled the fuel presure vacum hose and nothing changes, i have a guage in-line BTW. it starts, spits, farts, and falls on it's face. i was just looking at my old fuel pump and what is that on the end ?? a presure regulator. because i use one from a different pump. my new pump needed a couple of the fittings for a direct replacment. i wonder if i used a bad,, whatever it is ?? right-on long duck.

 

Yea I'm wondering that too. Hoping it is just a pulsation damper. Offhand, I don't see any way it can control fuel pressure. I'm about to put a Walbro in with the correct adapter fittings and I'm planning on re-installing the pulsation damper on the pump.

Anyway, about your problem, the pump can be running lots of fuel through the system and still be at low pressure. Basically you will always be operating on the fuel pump curve. You should see better than 12 v at the fuel pump terminals under load, if not figure out why it isn't.

So is the car running lean or flooding? This could help determine how to troubleshoot. Check you plugs are they wet after all this cranking to start.

The fuel pressure regulator does the same job as pinching off the return line. If the pressure is low, it pinches off the flow to increase the pressure (and yes this decreases flow).

Great write-up LongDuck, but I think it closes to increase pressure in the fuel rail.

I would try and do some sort of fuel pump flow/pressure test to see if you are getting what you need up to the engine.

The pressure regulator solenoid only comes to play on a hot engine. It closes off the vacuum line to the pressure regulator.

Hope some of this helps you out,

Scott

 

no, no flooding. the fitting i'm talking about is the curved
'banjo' type deal on the stock pump,or the 'out' side
of the pump, then to the filter. i've looked and looked everywhere i can to find out what that is on the fuel pump,, nothing yet.

 

just so you guys know,, there is a fuel presure regulator
right on the -SE fuel pumps. i switched mine and the engine fired right up and runs...stays running. no spiting,
no farting,. there are 2 presure regulators on -SE's
*******,,,,killer. thanks guys.

 

regulator

 

regulator

 

Hey, isn't that a pulsation dampner? The FPR looks like a solid brass mushroom that's mounted to the return line end of the fuel rail.

Also, thanks, Scott, for setting me straight on the operation of the FPR by shunting flow out of the fuel rail - that makes more sense and I'm sure that's how it works now that you pointed it out.

I'm glad you found your problem, and by documenting it here, it's available for future reference. I hope mine's still in good shape!

 

on my gslse, the people before me upgraded the whole fuel system, I have two fuel pressure regulators in the engine bay. One for receiving and one for returning. It also has a different fuel pump. Like an electric fuel pump.
You can see it in the pictures of my car, the one of the engine bay. www.cardomain.com/id/mazdagslse