Hard Starting: Fuel Pressure Issue
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    1. #1

      Hard Starting: Fuel Pressure Issue

      Hey guys,

      I've been having an intermittent hard starting issue for about the past month or so. Initially, it would just take an extra crank or so, but eventually start, now it's been taking much more effort. I've read through several similar threads, but I did not come across a cut and dry solution.

      I borrowed a fuel pressure gauge from AutoZone and have narrowed my problem down to most likely being fuel pressure related. After I get the car to start, the fuel pressure sits at about 41psi at idle. The fuel pressure appears to stay steady as it sits after being shut off. Also, it sounds/appears as if the fuel pump is coming on intermittently and not spinning up every time when the key is in position II--even when there is low fuel pressure at the rail.

      After it has fully started and resting at a steady idle, the car has never stalled or sputtered.

      I'm not sure if this sounds most like a PEM issue, or an intermittent relay issue, or a pump problem.

      Any thoughts or advice would be much appreciated.

      Thanks,
      Mike

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    3. #2
      Junior Member
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      My situation sounded very similar to yours. I started with the cheap stuff first like checking the battery and replacing the fuel pump relay and fuel pressure sensor. All easy and all cheap. Car would do better initially and then wouldn't want to start after being shut off briefly, but wouldn't stall after it actually started and ran. Then the issue got worse and finally I started to look for used PEMs on the web. Got one for $65 and haven't had an issue since. I don't know what year yours is, but if your PEM is next to your rear passenger wheel, I'd start with a used replacement first before spending $45 on the relay and sensor.
      2005 V50 T5 AWD 6MT

    4. #3
      Member TG's Avatar
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      Where is the "Subscribed button" on SS

      Has some know, I've had my share of starting issues as well. Much more so with cold temp. But still starting issues similar. I haven't figure it out yet... but I haven't had the time to do a few things I need to test.
      None the less I've noticed an increased amount of post on the subject recently. Something worth noting as theses cars are getting older perhaps (?)...
      Last edited by TG; 04-12-2017 at 04:24 PM.
      T5 S40 Greg (05) > 1. 2. 3. | Kenwood interface |Viva 3"DP |EST exhaust |RICA stage 2+ |EST trust brace |Elevate sway bar |Bell black FMIC | intake pipe |IPD TCV |H&R 1.4 down |IPD front end-links |Focus tran mount |BERN 18x8 on Michelin pilot super sp 225x40 |Bilstein 8 SP struts and shocks |Powerslot rotors |StopTech 309 pads |Custom Boost gauge |Lettering relocation head+rear lights cut vinyl |

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    6. #4
      Quote Originally Posted by eff naked teeth View Post
      My situation sounded very similar to yours. I started with the cheap stuff first like checking the battery and replacing the fuel pump relay and fuel pressure sensor. All easy and all cheap. Car would do better initially and then wouldn't want to start after being shut off briefly, but wouldn't stall after it actually started and ran. Then the issue got worse and finally I started to look for used PEMs on the web. Got one for $65 and haven't had an issue since. I don't know what year yours is, but if your PEM is next to your rear passenger wheel, I'd start with a used replacement first before spending $45 on the relay and sensor.
      Shoot, I had all that info in a previous post and lost it, I guess I forgot to add it to this one.

      The car is an '05 V50 T5 AWD with the M66. The PEM had not been replaced and is still residing in front of the right rear tire, under some plastic under-carriage cladding. Also, the FPS had been replaced a couple years ago, although I'm sure it's still possible for sensors to go bad in that time frame.

      From what I've read so far, I think I'm leaning towards replacing the PEM as well.

    7. #5
      Member pczeilon's Avatar
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      Your fuel pressure should spike much higher than 45 during starting. Think 60-65 or more. Where you live is a huge factor on the PEM. If they salt the roads in Winter I'd start there first. Coastal or areas of high rainfall next. If you live in Death Valley it's doubtful you have an issue with the PEM.
      Most times they fail completely by blowing the fuse but can give goofy errors like you are experiencing. Best thing to do is watch the fuel pump duty cycle in VIDA.
      2007 V70 5 Speed
      2005 S40 2.4i 5 Speed

      1995 855 5 Speed SOLD

    8. #6
      Quote Originally Posted by pczeilon View Post
      Your fuel pressure should spike much higher than 45 during starting. Think 60-65 or more. Where you live is a huge factor on the PEM. If they salt the roads in Winter I'd start there first. Coastal or areas of high rainfall next. If you live in Death Valley it's doubtful you have an issue with the PEM.
      Most times they fail completely by blowing the fuse but can give goofy errors like you are experiencing. Best thing to do is watch the fuel pump duty cycle in VIDA.
      It definitely spikes before/during startup (60-70psi), but settles down to ~41psi at idle. I can actually flip the key back and forth between position I & II and watch the fuel pressure gauge for the spike--there will be no movement on the gauge for several turns of the ignition, then it will jump up and that's when it will actually start.

      I bought the car about four years ago in Colorado (not sure where it had been the previous 9 years), then it spent a year in South Florida, and the past two in North Carolina.

    9. #7
      Member pczeilon's Avatar
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      Perhaps you need an ignition switch then. These are a common failure on the early models & have been updated several times over. If you don't get the spike when moving to II try tapping the key toward the dash with some force. Think small rubber mallet. See if this makes it go.
      2007 V70 5 Speed
      2005 S40 2.4i 5 Speed

      1995 855 5 Speed SOLD

    10. #8
      FOLLOW UP:

      So after suspecting the PEM being faulty, I removed it yesterday. A light shake and the rattling within the module was apparent. I cracked open the unit and it had a good amount of sand, etc. likely from the Colorado roads.

      This afternoon, I ventured over to the local pick 'n pull, found an '08 S40, and located a very nice looking PEM under the rear seat. $16 later and the preliminary results are looking good; the car started right up, no problems--and no problems starting the 4-5 subsequent attempts. We'll see how it goes over the next week or so.

      I Appreciate all the help.

    11. #9
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      2005 V50 T5 AWD 6MT

    12. #10
      Member pczeilon's Avatar
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      Go back to the pick/pull & score the small harness pieces so you can put it under your seat also. Although by 2008 they might have integrated it that way. Never worry about it again. If you find a car with a small jumper wire in the RR wheel well you know you have a winner. Take that jumper & the small harness that connects the PEM under the seat.
      2007 V70 5 Speed
      2005 S40 2.4i 5 Speed

      1995 855 5 Speed SOLD

    13. #11
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      Anyone have an image of the PEM behind the wheel well? i'm not sure what to look for. i looked under my rear seats to look for it but im not quite sure what i was looking for. Also, is the PEM interchangeable from other vehicles such as maybe a xc90, sc70, or s60s from similar years? if not i'll have to buy one online

    14. #12
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      It's a black plastic box with one connector plugging into it. One side will have an aluminum face for a heat sink. Just do a quick PEM search on eBay for your car and you'll get a few images to work with.
      2005 V50 T5 AWD 6MT

    15. #13
      Member TG's Avatar
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      Quote Originally Posted by V50_Mike View Post
      I bought the car about four years ago in Colorado (not sure where it had been the previous 9 years), then it spent a year in South Florida, and the past two in North Carolina.
      Wow, that car likes to travel!
      T5 S40 Greg (05) > 1. 2. 3. | Kenwood interface |Viva 3"DP |EST exhaust |RICA stage 2+ |EST trust brace |Elevate sway bar |Bell black FMIC | intake pipe |IPD TCV |H&R 1.4 down |IPD front end-links |Focus tran mount |BERN 18x8 on Michelin pilot super sp 225x40 |Bilstein 8 SP struts and shocks |Powerslot rotors |StopTech 309 pads |Custom Boost gauge |Lettering relocation head+rear lights cut vinyl |

    16. #14
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      is the PEM interchangable with other volvos?

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