All,

If you're following along here: https://www.brickboard.com/AWD/volvo/1657010/S70/cel_codes_p0172_pending_p0301.html

Then this is where I'm currently at.

Got my new fuel pressure tester gauge today and here is what I have found, and I'm stumped.

So for starters I attached the gauge and primed the rail by turning the key on and off till all I could get to was 38 PSI.

I believe that this is NOT an accurate leak down test, but I left if sit for 10 minutes, and within that time it dropped to 30 PSIs.

After that, I started the car and the gauge read between 42 to 44 PSIs while idling.

I revved it a few times and it read between 43 to 44.

I then proceeded to remove the vacuum line to the FPR and expected to see my gauge jump up. However what I saw was that it stayed the same value. So what does that mean to me? I also noticed that I had a pulsation coming from the vacuum line and not a steady pull. I believe I measured that it was pulling about 2 to 2.5 inches of mercury when I checked. Does that sound about right?

I then reattached the vacuum line and shut the car off, and here are my leak down test results.

@ shutdown, 38 PSI,
@ 10 minutes in, 40 PSI,
@ 20 minutes in, 38 PSI,
@ 30 minutes in, 30 PSI,
@ 40 minutes in, 28 PSI,
@ 60 minutes in, 22 PSI,

So as you can see, in my opinion, the car loses pressure rather quickly, but why???

Also I attempted to pull a vacuum at the FPR and from what I can tell it did hold a vacuum. I was running out of day light and my son needed the car, so I didn't spend much time with it, so I may have missed something there.

So in conclusion, removing the vacuum line from the FPR has no effect on the fuel pressure at the rail, there is a pulsation on the FPR vacuum line instead of a steady suck, but I don't know if this is normal or not, and finally the fuel pressure at the rail appears to bleed off rather quickly in my opinion, but I don't know what the spec is, and all I have to compare it to from a white block perspective is my 07 XC70, which holds much stronger and much longer.

Again as usual, any and all help on solving this lagging issue is greatly appreciated.

Matt
--
1989 - 245, 1990 - 245, 1991 - 245, and 1993 - 245

After discussing this with some co-workers today, it was suggested that I try pulling a vacuum on the FPR to see it was good or bad.

Since my wife had been driving the car today and it was still very warm, I decided to get this done before the rain came. Upon removing the vacuum line to the FPR I no longer had a clicking noise at the FPR. Interesting. I attached the vacuum pump and pulled the fuel pressure down from 44 to 38 and it held very nicely.

I did some research and found that the vacuum line goes to the front of the car and is controlled by this part:

https://www.fcpeuro.com/products/volvo-vapor-canister-purge-solenoid-c70-s70-v70-8627005

After I found it, I went out side and I was no longer getting any type of pulsation from it. I also tried pulling a vacuum at the line and I could not, so I must have a break somewhere as well, which now needs to be found. Ugh!

I've placed the vapor canister purge solenoid in my freezer for a while to see if the solenoid at least works. My thought is that it will, but when it gets warm it no longer will, therefore needs to be replaced.

Yea for me.

Problem solved, finally!!

Matt
--
1989 - 245, 1990 - 245, 1991 - 245, and 1993 - 245