Where is Fuel Pressure Regulator on 1998 V70 XC AWD

denvaa · Post by **denvaa** » 11 Jun 2010, 09:32

I was told i need to replace my fuel pressure regulator and am choosing to do this my self but not sure where it is on this model?

Post by **vjaneczko** » 11 Jun 2010, 09:47

Does this help?

https://www.matthewsvolvosite.com/forums ... 4&p=135182

jablackburn wrote:
That almost sounds exactly like the fuel pressure regulator. Which, on an AWD, is a COMPLETE PITA to get at, because it's on top of the fuel tank. Get a fuel pressure gauge and see if you can figure out anything else.

denvaa · Post by **denvaa** » 11 Jun 2010, 09:51

Well i am on that thread as well but i guess im hoping that somone has does this swap out before and may have pics or some sort of guidance. Do i need to drop tank? can you access this through access panel ... etc

Post by **FlyingVolvo** » 11 Jun 2010, 12:19

You have to drop the tank... OR if you are careful, you can cut a hole in the metal above it (in the trunk area) and make your own access port. There have been a few discussions about that on here, and so far it seems like a pretty good route to go.

When it comes to replacing my fuel pump hopefully in the far out future (knock on Swedish steel), I'll probably opt for the cutting method as it doesn't seem too difficult.

denvaa · Post by **denvaa** » 11 Jun 2010, 12:45

I was just told by three places it on the fuel rail for my model 1998 V70 XC Turbo AWD .... why am i getting so many answers ... ugggg

Post by **jblackburn** » 11 Jun 2010, 13:35

That's the fuel pressure damper. An XC/AWD model has a different fuel system than the rest of 'em, but the regulator is at the back of the car.

https://www.matthewsvolvosite.com/forums ... 6&p=121589

^Take a look at the PDF there.

Post by **jblackburn** » 11 Jun 2010, 13:39

This is from a Porsche forum, but explains the differences between the two components:

On a 928, you'll notice that the "damper" or "dampener" is located at the "IN" end of the fuel rail. This seems odd at first, because the damper is there to absorb pressure waves in the fuel rail from the injectors, therefore it should be at the end of the rail, no? No. Since the 928 does batch fire, the injectors all fire at once , ergo no big waves.

However, the Bosch roller cell style fuel pump does generate some pressure waves - so the damper is really there to absorb those waves, and to act (sort of) like an accumulator. It builds up a "pressure reserve" before all them durn injectors fire again.

The regulator does just what you think it does - it regulates the pressure the injectors 'see' by allowing a certain amount of fuel to be returned to the tank. The vacuum reference allows more fuel to return to the tank during periods of high vacuum (like ~25 kPa absolute) like you see at idle, or during over-run.

How? The damper is just a spring loaded diaphragm and so is the regulator. Though the 928's damper is vac referenced, most aren't. Think of it as a trampoline in a tube. Or (almost exactly) like one of those anti-hammer jugs you put on your hot water lines. Tube contains a flexible membrane on one side, and a spring on the other. Fuel flows under the membrane, membrane flexes at some predetermined rate to absorb the 'jumping' fuel pressure.

Post by **vjaneczko** » 11 Jun 2010, 13:57

denvaa wrote:I was just told by three places it on the fuel rail for my model 1998 V70 XC Turbo AWD .... why am i getting so many answers ... ugggg

I guess you're getting all these answers to help figure out what shops to avoid!

denvaa · Post by **denvaa** » 11 Jun 2010, 14:48

jablackburn wrote:That's the fuel pressure damper. An XC/AWD model has a different fuel system than the rest of 'em, but the regulator is at the back of the car.

https://www.matthewsvolvosite.com/forums ... 6&p=121589

^Take a look at the PDF there.

That is for a 2000 its the same for 1998? I was told the damper was not used untill 99

Post by **jblackburn** » 11 Jun 2010, 14:58

Yes.

Here are the instructions for a 98 XC (I think they're identical).

My 98 T5 has a dampener, but like I said, they're different in the AWD models.