Bad fuel ecomomy - fuel pressure is the key - Volvo-Penta bulletin P-23-7

JohnnyCakeJohnnyCake Helsinki, FinlandMember Posts: 29 ✭✭
edited June 2015 in Engine Discussions
We have 2006 Rinker FV250 with Volvo-Penta 5.0 GXI-E 270hp (400hours).

We have been suffering from poor fuel economy for a past two summers. Our fuel economy sank over 25%, from average of 2 liters/ Nautical Mile to  2,6 liters / Nautical Mile. This means about 100-120 gallons extra fuel per summer for us.

I have checked almost everything and couldn't solve the problem. I even changed the distributor, since it was quite rotten inside and could lead to weak spark. It helped some, but didn't solved the problem. ( http://rinkerboats.vanillaforums.com/discussion/2151/fv250-volvo-penta-270hp-fuel-economy-issue-solved)

Couple of days ago I decided to change spark plugs. The were very black and dirty (see the picture below) which means that the engine is running very rich.
At the same time I changed the fuel filter. When I started the engine, I could hear a quite loud whining noise from the fuel pump.
Since the engine is injection engine and the fuel pump was whining, this was the key to find a problem. If the pressure in the fuel system is too high, the engine will get too much fuel. Engine adjusts the fuel mixture by adjusting fuel pressure. I googled and the fuel pressure should be around 45psi. I borrowed a fuel pressure gauge and when a started the engine, pressure went to 90psi and didn't stay steady, it was jumping between 75-100. This caused cavitation inside the high pressure fuel pump  and made the whining noise.

Some more googling, and I found this VP bulletin about fuel pressure regulator (it allows fuel to route back to filter if the pressure is too high in the fuel pipes on the engine). This bulletin is also attatched to this post.

https://www.dropbox.com/s/i3y1kznhp9btg7g/156 PB P-23-7 N03 V01 Fuel Pressure Regulator.pdf?dl=0

You really should read this thru. This is important. This bulletin indicates the problem with all engines older than 2010.

I opened the regulator and it was cloaked. I changed this screen with the pin mentioned in the bulletin and started the engine. The fuel pressure was 46psi!
So the problem was a faulty fuel screen, worth $2, and it took 10minutes to change with a since screw driver. Sometimes a small problem causes big struggles.. D

I guess the problem has started 2-3 years ago and got worse all the time until it was so bad the fuel pump didn't work anymore. This was the key finding. I hope this solves somebody else fuel economy problem without two years hunting. :)

Pics:

Bad spark blug vs new



Fuel screen inside the regulator:


Finally, a correct fuel pressure:

Comments

  • Handymans342Handymans342 Member Posts: 10,375 ✭✭✭✭✭
  • Dream_InnDream_Inn Annapolis, MDMember, Moderator Posts: 7,093 mod
    That is a great find!  I'd say it is something well worth changing out even if you don't think you have that problem!!

    Dream 'Inn III -- 2008 400 Express

  • MarkBMarkB OntarioMember Posts: 3,871 ✭✭✭✭✭
    Very good detective work. Glad it is a simple fix. And great instructions, this will help a lot of people in the future.

    Boat Name: King Kong

    "Boat + Water = Fun"

  • andydandyd Dana Point, California, USAMember Posts: 846 ✭✭✭
    I have the exact same year and model of boat with the same engine. I'm not suffering the fuel problem you describe, but thanks for this valuable information. Forewarned is forearmed as they say.

    Andy
  • andydandyd Dana Point, California, USAMember Posts: 846 ✭✭✭
    I just ordered the E-clip and boosted the Swedish economy by $3.17. UPS did a bit better than that for shipping.

    Andy
  • JohnnyCakeJohnnyCake Helsinki, FinlandMember Posts: 29 ✭✭
    Andyd, You also might want to check this out, since you have the same engine:

    rinkerboats.vanillaforums.com/discussion/1899/volvo-engines-check-your-oil-hose-connectors

  • andydandyd Dana Point, California, USAMember Posts: 846 ✭✭✭
    Thanks for the tip. Yes, I saw that, it was an ugly mess. My lines look OK, but who knows if a leak is around the corner. As a bit of an extra precaution I plan to wrap the fittings with Rescue Tape. www.rescuetape.com

    Andy
  • andydandyd Dana Point, California, USAMember Posts: 846 ✭✭✭
    I bought the E-clip weeks ago, but had not gotten around to installing it. I really don't know if my fuel pressure is out of spec and I don't have a gauge, but since the factory called for the replacement of the screen with the clip I thought I'd go ahead as a preventive measure.

    Removing the regulator was easy, pull the retaining pin, and after a wiggle or two it came out. The fuel inside was milky, not sure why.

    Prying off the old screen was a bit difficult, and you can see I damaged it. Now I'm all-in! I cleaned up the regulator and snapped on the E-clip. Piece of cake. The O-rings were in good condition.
    I reinstalled the regulator and then the moment of truth. Will she run? Well, yes she did, all is well and it may be wishful thinking, but the engine sounded healthier than usual. A fairly easy project for anyone reasonable handy.

    Thanks to our Finnish friend JohnnyCake for bringing this to our attention. The bulletin from VP made the install straightforward. Anyone with pre 2010 5.0 VP power should do this fix before the high pressure problem happens. 
    I love this forum!

    Andy
  • Handymans342Handymans342 Member Posts: 10,375 ✭✭✭✭✭
  • Michael TMichael T Member Posts: 7,202 ✭✭✭✭✭
    That will help a lot of people thanks to you and JC.
  • andydandyd Dana Point, California, USAMember Posts: 846 ✭✭✭
    Thanks. FYI the bulletin applies to pre 2010 gas EFI 5.7 motors also.

    Andy
  • The Main ExchangeThe Main Exchange Kansas City, KSMember Posts: 280 ✭✭✭
    Is it applicable to the VP 8.1? I know a member just cleaned paint out of his regulator on the fuel pump assembly.

    2007 300 EC, 350 Mags, B3's, Table Rock Lake, MO

  • TazTaz Member Posts: 62 ✭✭
    Guys if you buy a new regulator will it come the clip already fitted ?
  • redlightningredlightning Beaver Lake ArkansasMember Posts: 284 ✭✭✭
    I did this update and its super easy.
    Searching for my next boat
    2012 390 Sea Ray Twin 8.2’s Inboard - Sold
    2008 330 Express Cruiser - Sold
  • tazataza Member Posts: 64 ✭✭

    Just a thought ?

    whats going to stop the crap getting into the ejectors if you take the screen out

  • BellevilleMXZBellevilleMXZ Ontario,CanadaMember Posts: 732 ✭✭✭
    The screen is on the return...
    ..does nothing to keep debris from.injectors
    2005 Rinker 270 FV Volvo Penta 5.7Gi
  • jhmiller10jhmiller10 Member Posts: 3
    Thank you for the tip. I was burning over 34 gph at cruise in my 320 with 5.0. The screens were plugged and my plugs were black. I cant wait to see how well she does!
  • tap12ptap12p Member Posts: 2
    Thanks for the information it worked for me engine was running rough and rich
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