Engine & Gearbox CDTi Fuel Pressure rail relief valve?

Discussion in '7th Generation (2003-2008) [Acura TSX]' started by Heckler, Friday 5th Apr, 2019.

  1. Heckler Club Moderator Club Staff

    It's been suggested via another forum that the problem I have starting the car when warm.. may be related to the fuel pressure relief valve and not the filter.

    I'm getting the filter done regardless next week as I don't know when it was last changed and it 'could' be the problem.

    Which brings up a few questions

    • where is the pressure relief valve and is there any way to check it?
    • Is this a common component on the CDTi PFL/FL models?
    • Can I test it?
    • How much is a new one?
    • Is this one of those Honda only parts?

    I found this on ebay... is that the right part, because at those prices I can order one right now.
  2. Zebster Club Veteran ★ ★ ★ ★ ★

    The over-pressure relief valve is on the driverside end of the fuel rail. When leaking, it is a common cause of poor starting, particularly when warm... the leaking fuel returns to the fuel tank and the pump becomes unable to achieve the necessary fuel pressure (200 bar) at cranking RPM.

    All common rail diesel engines have this protection device.

    You cannot get it from Honda, instead they will try to sell you a complete fuel rail! I'd recommend getting a replacement valve from a Bosch Service Centre (it's made by Bosch).

    You get the exact same symptoms if an injector has developed an excessive leak back flow, so you really should see if the valve has developed an internal leak before splashing out. Here's a giant thread on the excellent Civinfo forum that explains how to confirm and solve this problem (you will recognise my avatar on many of the posts!)... https://www.civinfo.com/forum/how-g...er-pressure-relief-valve-2006-2-2-i-ctdi.html
    SayamaAccord and Heckler like this.
  3. Heckler Club Moderator Club Staff

    OK, reading through that thread... it does sound more and more like my issue. Sent an enquiry to the seller to confirm part is compatible for my car/engine... Seems like a job I can do myself, providing I've got the right tools. I know I've got 17mm sockets... But I think my ratchet that fits those ones is the busted one. I'll check my spanners as I'm pretty sure I've got a 17mm or two... probably ring spanners too... or there's my impact wrench to get it off. :Smile:

    From the reading I've done, it seems to point more to the valve than an injector... She runs sweet when started and MPG's have been good so far, getting around 3-4mpg more than the tourer around town... But haven't done a long motorway run yet. I'd be tempted to buy the valve and try it along with a new fuel filter.
  4. Zebster Club Veteran ★ ★ ★ ★ ★

    It would still run fine if it was an injector with excessive leak-back... there are two separate paths through the injector, one to put fuel into the engine, while the other is for lubrication and this flow path exits at the top of each injector into daisy-chained pipework that returns this fuel to the tank. The lube path flow increases as the injector wears and will cause the starting problem you describe, although less common than the rail over-pressure valve.

    It's easy to check the valve. And, if it is passing fuel, then you won't need to bother replacing the fuel filter!
    Last edited: Saturday 6th Apr, 2019
  5. Heckler Club Moderator Club Staff

    I can't find a part number for this valve... I can't even find it on lings, and looking for a bosch service centre isn't giving me any results for buying parts... Only getting my car serviced.
  6. Zebster Club Veteran ★ ★ ★ ★ ★

    Ling's is a Honda dealer and, like I said, Honda don't sell this valve separately... they only sell a complete fuel rail assembly (complete with the valve and the pressure sensor) for about £1.5k!

    The first post in the Civinfo link (above) gives the part number... "A common number on the part found on the old and new valve was F166. On the part receipt it was called a "pressure limiting valve" p/n F00R001166". Later posts in that lengthy and detailed thread give a variety of suppliers and costs for that part.

    I've bought quite a few parts from Bosch Service Centres, but have always done it over the phone. If you can find a genuine Bosch replacement on eBay or Amazon then I'm sure that would be OK, however there is lots of cheap crap around that personally I would avoid.

    I just had a look on eBay... this one seems suspiciously cheap, however it appears (?) to be genuine:- https://www.ebay.co.uk/itm/HONDA-Ci...4ef9534&pid=100623&rk=1&rkt=6&sd=281795258636
    Heckler likes this.
  7. Heckler Club Moderator Club Staff

    I've found plenty of parts listed under that part number for around £120+... also found loads that are cheaper and state they're bosch parts but there's no part number listed just the compatibility for my car. Hence asking sellers to confirm part number... Seems to be the same part across the CDTi and DTEC engines for the Civic, Accord & CR-V... Maybe others as Bosch supply parts to countless manufacturers.

    Fingers crossed some one can answer my query before Monday so I can get it ordered today.
  8. Zebster Club Veteran ★ ★ ★ ★ ★

    But you haven't yet diagnosed that your valve needs replacing. It's so simple and could save you the cost of the part and the trouble of replacing it... they can be hard to shift, I'm pretty sure they are installed using some sort of threadlock due to the 1600 bar running pressure.
  9. Heckler Club Moderator Club Staff

    I was hoping to do that this morning... if it gets a little warmer... Just need to find a bit of tubing and a bottle if I understand the procedure right.
  10. Zebster Club Veteran ★ ★ ★ ★ ★

    Sounds about right. Basically you need to reroute the valve outlet (a stub on the rail) into a container and check that there is no flow when the engine is running. The original pipe that you need to remove from the stub has to be plugged (with a suitable bolt, etc). Just follow post #1 of that Civinfo thread and you'll be OK!
  11. Heckler Club Moderator Club Staff

    Just popped out there after putting my chunky jumper on... Checked the car started... was fine the first and second times... started struggling on the 3rd try. (10 secs between each attempt) I located the pipe on the right and the valve on the left... Managed to pull the pipe of and after turning the car over, there was a little bit of fuel in the bottle. I don't know how much there should be or how much means the valve has failed... maybe I didn't turn it over enough.

    I checked all of the other pipes and leads for leaks to the injectors and so forth... Couldn't find anything abnormal.

    But what I did find could be a problem... on the Accord the power steering pump sits right in front of the valve... There is no way you're gonna get a socket on it as there's not enough room. for one. I did take a pic of the end of it so I can check the numbers.markings. I may be able to get a 17mm ring spanner on it, but there's not enough room for a socket/ratchet.
  12. Heckler Club Moderator Club Staff

    OK, so trying to find the right part... I took a pic of the writing on the valve fitted to the car... which has the F166 written on it as mentioned in the Civic thread.
    2019-04-06 09.19.01.

    But every part I find that says it's compatible... and these state they are Bosch parts for the car, have the following info written on the top. I've checked about 8 or 9 now and they're all the same. I assume that the top number is a date/batch number from manufacture. The 087 number matches, but the lower left number is 1015 not F166.

    I'm about 60% certain I need to replace it and I've found them online (stating they are Bosch parts for £35-50 and others for over £100) and others that are probably knock off's for £20-30. I'd go with the Bosch part obviously and it's half what the Civic thread said they cost (although it is a very old thread (5yrs old) and part prices could have come down)
  13. Zebster Club Veteran ★ ★ ★ ★ ★

    If fuel is actually being passed by the valve, then it needs replacing... It's a protection device that should only pass fuel in the unlikely scenario that the fuel pump pressure becomes uncontrolled.

    Just to be clear, it's the outlet stub on the driverside end of the rail that you are checking, NOT the pipe that you pull off (which will emit fuel when the engine is running, due to the other flow paths back to the tank).
  14. Heckler Club Moderator Club Staff

    I used the pic on the civ guide, and that showed the pipe connecting to a metal tube on the right side of the fuel rail.. from the look of it, it comes of the rail near the valve and routes along behind the rail to that fitting... and that pipe is at the opposite end to the valve. untitled.
  15. Zebster Club Veteran ★ ★ ★ ★ ★

    Yes, as you should be able to see (if you remove the engine cover) it's merely a connection further along the tank return pipe from the stub on the rail.
  16. Zebster Club Veteran ★ ★ ★ ★ ★

  17. Heckler Club Moderator Club Staff

    Yeah, I did update my project log... Had it done yesterday and cost £53.50 for the part and fitting (£35.50 and £18). I tried and tried to loosen it off but couldn't... So popped down to my local garage and they squeezed me in between jobs. Took about 15 mins.

    You do need to loosen of the power steering pump and rotate it out of the way about 1-2cm to gett he valve out... and then when trying to put it back, a long ring spanner on the tensioner to apply pressure to be able to push the PS pump back into place and slide the top bolt back in. That part is really a 2 person job... One to apply pressure tot he tensioner and another to push it back and slide the bolt in... Unless you loosen it off and slip the aux belt off.

    So the civ guide is great, but the accord has far less room to work in due to that pump.
    2019-04-10 11.53.28. 2019-04-10 11.53.38.

    and whilst we were working around the PS pump.. found a leak in the pipe. So I've ordered a new one and will get that fitted next week.
  18. Zebster Club Veteran ★ ★ ★ ★ ★

    Once the aux belt is slipped off, the PAS pump is easy to unbolt and move slightly. An open jaw spanner can be interlocked with a double-ended ring spanner to improvise a tool to relieve the tensioner, or a pipe extension can be used with a ring spanner (but this does need to be bent properly for clearance). Or the rail can be removed and held in a vice while the valve is replaced.

    Has it fixed the problem?
  19. Heckler Club Moderator Club Staff

    Oh yeah, she's starting first time every time now.