XC90 V8 Intermittent fuel pressure cutout (kinked fuel pump line) Topic is solved

[SHOCKWAVE]

@mrbrian200 - Thanks for the input.
NOTE: I still haven't got VIDA running yet, so I'm just adding a few more bits of info. I'm going to try this method using a Macbook Pro running VMWare Fusion: http://forums.swedespeed.com/showthread ... nload-Link
-Is there a way to determine if the PEM is faulty? An electrical fault seems very reasonable to me, as it does fight to recover when the issue is present, and then it disappears (4/5 times) after the car is shut down and restarted. The PEM looks almost like new under there:

SHOCKWAVE'S PEM

2007_xc90_pem.jpg (121.82 KiB) Viewed 7212 times

-I've posted the wiring diagram, 2007 (and a 2005 for reference).

[mrbrian200]

Unfortunately I don't know the specific procedure to test it. I suspected a problem with it (fuel pressure wouldn't go above ~45psi). Before spending $ on a new one I tried reworking the internal circuit board with a soldering iron which fixed it (pressure would rise to ~60psi under hard acceleration). Most people who aren't familiar using a soldering iron around a board with very small surface mounted components would probably be better to replace it rather than cracking it open.

I'm not even sure if the control signal from the ECU (yellow wire) is varying DC or PWM. I never got into those specifics because the details aren't really out there that I could find.

In your case first I would try unplugging and cleaning the contacts at connector 54/36, and check the ground 31/48. These PEMs aren't terrible expensive used, it came from a collision vehicle chances are it'll be good. I hate replacing parts on a haunch without verifying for sure that it's bad.

[SHOCKWAVE]

-I finally managed to get VIDA running. Hopefully, my DICE unit will work and hopefully get more info.
-I'm suspecting the PEM based on the symptoms, so I'll take a stab at throwing a part at it for what seems a good deal. I didn't think they'd accept my offer of $50, but they did immediately.

[Roger_850T]

I'd love to know how they Tested it and confirmed it "Work's Prefect"!? Anyway, that sounds like a good deal, and I hope it works for you! Keep us posted!

Roger

[mrbrian200]

I'd love to know how they Tested it and confirmed it "Work's Prefect"!? Anyway, that sounds like a good deal, and I hope it works for you! Keep us posted!

Roger

The PEM being plug and play it would be one of the easier parts to test. Pretty much all you need is another Volvo that uses it which you are familiar with/drive regularly.
If OP lived close I'd offer to plug his PEM into my car just to confirm or dispel that it's bad. It would take all of about 5 minutes. 4 or which is opening the trunk and plugging it in, then 1 minute to start the engine, pull out of the driveway and stomp on the accelerator. You'd know instantly.

[SHOCKWAVE]

Ok, so it is my first time using the software, so I hope I got enough info to add to this diagnosis.

Please look over the screenshots and let me know what you think or if I should try to pull additional data.
NOTES:
-I've indexed the images with numbers so you can refer to them by the numbers.
-The torque converter code (00) I attribute to the first time the fuel cut out as it didn't recover until I pulled over and shut it off. IIRC no codes were thrown on this instance.
-The timeline only shows the last instance P08900 was thrown (12/28/17). I erased it using the OBD wifi unit. IIRC the code only popped up 2/5 times.
-I am not sure about the time on image 05. I was taking my son to the ER when it happened, and we were at the hospital <10minutes after (filled up with gas to "fix" the drivability issue). Image 04 time should be correct. Thank God that happened close to a gas station. I didn't start the car again until 1am or so.
-Very uneven capacities in the tank(s).
-No change (nominally) in fuel pump duty cycle under load.
-Fuel pressures: Patm= 101 kpa, 609kpa = 88 psi, 480 kpa = 70 psi, 413 kpa = 60 psi, 380 kpa = 55 psi, 156 kpa = 23 psi
-Fuel regulation reference: http://workshop-manuals.com/volvo/xc90_ ... operation/

[ggleavitt]

If you have the opportunity, go into the Delivery tab and erase all codes (follow instructions so they're actually erased) then see what pops up as legit.

For the difference between fuel tank senders, entirely possible the driver side sender has some wear on the rheostat, replaced mine on the '05 a few years back, after a DTC popped up from time to time. Makes no overt difference to driving, at least as far as I've been able to tell, just makes the level closer (and they'll never be exact). Could be something I'm missing but in reality were this to come up again, I might just have lived with it. Can see link for my story- http://forums.swedespeed.com/showthread ... Difference, since you're not getting a DTC on this, probably nothing to resolve.

Another description as to how the fuel system works in VIDA- Product Specifications/Design and Function- 284: Engine control module (ECM), B8444S.

[Roger_850T]

Did you receive and install your replacement controller yet?

Looking at the screenshots you uploaded, and especially at the one with the graph... In that one it looks like everything is running as it should - fuel pressure is maintaining a constant value, ECU signal to the fuel pump controller is essentially constant; then when you lift off the throttle the reduced demand causes the pressure to spike and the ECU requests a lower pressure, until the pressure comes back down then the ECU goes back to the normal pressure and the controller controls. It all seems to be working.

Going back to your original post, it seems that it all works, until something goes wrong and causes it not to provide enough pressure. I think in my case I have the sensor problem, and the substitute value that the ECU uses works just fine. In your case, I think the pressure really does go low, for some issue with the controller, causing your driveability issue.

When you put in the replacement controller, I would also inspect the wiring very carefully for anything that might be intermittent - failing wire, corrosion, any connector that's loose, anything like that which could move and cause the intermittent behavior.

I'll try and get a snapshot of mine doing the same drive test, for comparison.

Roger

[SHOCKWAVE]

MINOR UPDATE...

• I received the controller (PEM). How was it tested...The ebay seller indicated they were fixing a problem on the host car and tried a new PEM which did not fix the problem. Since they installed the new one, they sold the old one.
  I erased the codes in VIDA.
• -TEST DRIVE- I haven't been driving the car much, but last night I warmed it up for 15 minutes and then drove for approximately 5 minutes @ 3k rpm in 2nd gear. No issues.
• I'm hesitant to put the replacement PEM as it would add an additional variable.
• I've posted the volvo functional description for reference.

NEXT STEPS...

1. Remove the magnets from the tank straps and drive for 30 minutes "hoping" the problem comes back
   • Most likely dirty fuel tank/ pump screen element - remove pump and inspect screen along with the tank and try to clean it in situ. I have a wifi borescope to possibly look around in there. Drop magnets in with a string to see if anything comes up.
     
     ?Anyone have an efficient tank draining method? How much fuel can be left in there?
     
     ?Fuel Pump Access Suggestions? This I may have to figure out on my own as I've looked at a few threads but couldn't find a comprehensive guide on how to do it easily. https://ozvolvo.org/discussion/5714/xc9 ... eplacement
     

     

     3rdrowseat.JPG (138.11 KiB) Viewed 7088 times

     ?Bleeding the fuel lines? I assume pressing the schrader valves to release fuel would suffice
2. Replace PEM and hope that was the issue- I'd really like to know how to check if it's faulty...You'd think there would be a check (Put voltage across the pins and measure resistance on another...) From the symptoms when it occurs, my guess is the PEM is sending a PWM signal for 50% of what it should (200kpa). The ECU fights back and sometimes wins getting control back to normal (480kpa). But then the PEM gets control again and cuts pressure by 50% of ECU request (back to 200kpa). This all happens relatively fast and you can tell there is an electronic control battle . Now IIRC, once the DTC trips or I shut the car down and restart, the PEM and ECU are in agreement unless the PEM freaks out... for whatever reason...this disagreement was 90% persistent the instance I had it towed. It was apparent that it wasn't going to recover (maybe til at least it cooled off.) Otherwise, it's been able to get control back.
3. Inspect CEM for possible corrosion- this seems to be a lengthy process to get access...
   
   
4. Take it in to dealer for diagnosis- It doesn't seem like they'd be able to do anything I haven't yet...
5. Throw in the towel, sell the car since I can't trust it...even though it appears to be fine. I really don't want to do that because I really like the car . My 3 kids (incl. newborn)/wife/upcoming CALEXIT will prevent this saga from continuing much longer

[abscate]

Shock...I just cleaned and recovered by PEM on my 2005 V70 and ordered a new one,

If the part is the same, do you want try my old one as a swap in?

Pm me , I'll check on the part number

On edit,,missed the second part of thread. You should check the supply from the CEM to the PEM and make sure your pEM is getting a good 12 VDC supply. For an intermittent problem you might need to rig up back plane wires and watch voltage in real time. Same thing with fuel pressure monitoring. You can monitor it under hood for a test drive with a fuel pressure gauges , an IPhone, movie mode, and,lots of duct tape