Volvo Fuel Module on my Mercruiser?

Discussion in 'Gas Engines/Drives/Transmissions/Props' started by William Miller, Jun 27, 2019.

  1. William Miller

    William Miller Member

    186
    Mar 16, 2007
    Darnestown, Maryland
    290 AJ
    Twin Mercruiser 300 hp Bravo III
    THIS IS A DISCUSSION TOPIC TO GAIN KNOWLEDGE!
    My 2006 Sea Ray 290 Amberjack is in great shape. I have owned and maintained it since it was new. I love to work on it and make it better, reliable and easier to maintain. I plan to hav it a long time.

    Fortunately, i have been able to keep it on a lift for its entire life. Unfortunately when i leave the lift the water is very shallow and the silt is ingested. Its been a burden because I've chased periodic overheating issues since i have had the boat. Fortunately that situation has changed but I will now be keeping it at a Marina with deep water.

    This winter, I pulled the engines to do a lite rebuild and mostly see if the cooling passages in the blocks were ok. Pulling the core plugs, i found what i had expected. Silt caked in the water jackets. These engines only have 400 hours and except for the silt they are in almost new condition.

    Off to the Machine Shop!
    After cleaning, magniflux, and pressure testing. All was great to rebuild with little machine work except for a valve job...while we were there. Honed the cylinder, New main and rod bearings and I have one almost back together.

    I'm looking over and painting all the acessory items. Replacing some and considering what i should do while i have them out.

    First: I have already replaced Mercruisers sea water pump and bravo water intake with a thru hull, big strainer and a Sherwood crank drive pump. (four screws on the front and maybe 15 min to change the impeller.

    Second: i was inflicted with a leaking fuel injector and while looking for replacement injectors I came upon an original equipment (made by GM) complete intake manifold with injectors (I mean the whole thing with sensors, throttle body ect.) for $300 each.
    I bought 2 and it was for real! Showed up in a GM box with GM part number.
    I now have one mounted on my engine.

    SO to the topic:

    This intake system is used by both Mercruiser and Volvo Penta (so it was advertised) my guess it was part of the Crate Engine Both Mercruiser and Volvo sourced from GM.
    I am not thrilled with the design of the Cool Fuel III system and especially the tiney proprietary filters that we are require to buy for an arm and a leg. My blocks (although i have not been plagued by the paint issue) are not in great shape. I am intrigued by the simplicity/the aftermarket cost and the easy to change screw on filter.
    The only technical difference i see is that Mercruiser uses return-less fuel plumbing while Volvo has a return fuel line.

    I know I will be bashed by Mercruiser Purists. But remember...This boat is MY TOY.
    I can do what I want. What I want is to make it Better, Easier to fix and Maintain, and less costly to own.

    Let me have it!

    Thoughts?
     
  2. techmitch

    techmitch Well-Known Member GOLD Sponsor

    May 1, 2008
    Chesapeake Bay, Middle River/Frog Mortar Creek MD.
    1999 270 DA
    Twin 4.3s W/Alpa I Gen II's
    A return less fuel system requires a different fuel pump, fuel rail pressure sensor, fuel pump driver module, wiring harness, injectors and ECM if it would even work with your current engines is unknown.
     
  3. techmitch

    techmitch Well-Known Member GOLD Sponsor

    May 1, 2008
    Chesapeake Bay, Middle River/Frog Mortar Creek MD.
    1999 270 DA
    Twin 4.3s W/Alpa I Gen II's
    PS, on the rod and main bearings, never been a fan of just replacing just the bearings and not a crank kit regardless of the hours/miles on the engines. The cost of a crank kit as opposed to just the bearings is minimal considering all of the work involved if you gotta go back in.
    Did you plastigage the crank/bearings upon assembly?
     
  4. William Miller

    William Miller Member

    186
    Mar 16, 2007
    Darnestown, Maryland
    290 AJ
    Twin Mercruiser 300 hp Bravo III
    please explain crank kit. One engine is together. The other one is just getting started.

    I have a lot of faith in the owner the machine shop. He inspected all of the parts and measured the block and the crank. He was impressed with what he saw and I followed his recommendations. I have rebuilt many engines and by far i am impressed at how simple the small block engine is. I am certain that these engines will serve me well for a long time. By the way. I am really enjoying this project.

    On the fuel system. You are hitting on some of the issues I am very interested in learning more about. First, i was intrigued by the statement I read that the intake I bought was for both Mercruiser and Volvo. I risked $600 to see if it would be in-fact a direct replacement for mine. Visually it looks exactly the same except the fuel rails are stainless instead of the crappy paint job Mercruiser did. I bolted one down on the first engine and it fits perfectly. I have not, but will verify that the injectors and sensors are the same.

    So, if the intake, as a complete part is the same part number for Mercruiser and Volvo, why would they have different injectors?
    I'm wondering if the difference lies in what Mercruiser attaches to the gm part vs what volvo does. Mercruiser simply put a quick connect cap on the return line.

    I'd like to understand the difference between return-less and what volvo does.
    Which is a better system?
     
  5. William Miller

    William Miller Member

    186
    Mar 16, 2007
    Darnestown, Maryland
    290 AJ
    Twin Mercruiser 300 hp Bravo III
    fuel pump 25.jpg
    Fuel Cell arrived today. Just one idea to mock up and figure out a good location.
    Not shown yet is my crank driven raw water pump.
     
  6. William Miller

    William Miller Member

    186
    Mar 16, 2007
    Darnestown, Maryland
    290 AJ
    Twin Mercruiser 300 hp Bravo III
    The port engine showing a better angle of the new intake. The blue and red caps on the fuel rail are the supply and return to the fuel cell.
    Mercruiser only uses the supply and the return has a cap.

    The starboard engine block is on the cart on the left.

    port 25.jpg
     
  7. William Miller

    William Miller Member

    186
    Mar 16, 2007
    Darnestown, Maryland
    290 AJ
    Twin Mercruiser 300 hp Bravo III
    GM Intake straight out of box intake 25.jpg
     
  8. William Miller

    William Miller Member

    186
    Mar 16, 2007
    Darnestown, Maryland
    290 AJ
    Twin Mercruiser 300 hp Bravo III
    GM Part Number
    GM 25.jpg
     
  9. Henry Boyd

    Henry Boyd Well-Known Member GOLD Sponsor

    Apr 24, 2007
    Newburyport, on the peaceful and serene Merrimack
    ‘09 Sabre 38 Hardtop Express “Serenity”
    Volvo D6 w/IPS450 Pods
    The fuel return is a form of pressure management. Big powerful pump puts out more fuel than injectors can ever use, metering is done by controlling burst timing and duration ,and of course injector bore. By over pressuring the system the impact of pressure drop and flow under acceleration is mitigated. The returnless system relies more on the ability/capacity of the fuel pump to keep up with the demand from accelerations. Personally my thought on which ever is better is a matter of opinion. Downsides a return system has more parts that can leak and go bad. A return - less system is critically dependent on the fuel pump. That said, marine engines are less likely to be frequently accelerated, vs a car or truck, more typically moved steadily to a set rpm.

    As an FYI, GM used a return system on the L series v8s.

    But you can see that while physically using the same manifolds the two systems have significantly different stuff bolted to them.

    Henry
     
  10. Henry Boyd

    Henry Boyd Well-Known Member GOLD Sponsor

    Apr 24, 2007
    Newburyport, on the peaceful and serene Merrimack
    ‘09 Sabre 38 Hardtop Express “Serenity”
    Volvo D6 w/IPS450 Pods
    Say that isn’t a mid eighties 930 sitting on that lift by any chance?
     
  11. PlayDate

    PlayDate Well-Known Member

    Dec 25, 2006
    Washington DC
    1994 370 Express Cruiser
    454 Mercruisers
    I’m working on a couple of Volvo 5.7 GSIs (on a Four Winn’s) for a slip neighbor. Volvo basically contracted with GM for the small block engine. The GSIs are Throttle Body Injection and use a very simple fuel system mounted on the front of the engine. 15 minutes to change/replace and the part is only $250.

    I wish they had put on a remote oil filter because they are a: “lay on the engine and reach underneath hope it comes off” version.
     
  12. William Miller

    William Miller Member

    186
    Mar 16, 2007
    Darnestown, Maryland
    290 AJ
    Twin Mercruiser 300 hp Bravo III
    Henry, i figured out that its not a returnless system.... because there is a fuel pressure regulator on the cool fuel3 modual. The return of the excess fuel happens there.
    I guess the fuel regulator on the fuel rail is redundant because there is no return line.

    The red car is a '81 911SC with a Carerra tail. Its got a 3.6 litre engine from a 964. Built to almost 275 hp without the turbo lag.

    The yellow is a 1966 Karman Ghia im restoring for my uncle. 1 owner car.
     
  13. Henry Boyd

    Henry Boyd Well-Known Member GOLD Sponsor

    Apr 24, 2007
    Newburyport, on the peaceful and serene Merrimack
    ‘09 Sabre 38 Hardtop Express “Serenity”
    Volvo D6 w/IPS450 Pods
    I had a 93 964 RS America I bought new. That thing was also guards red and scary fast. In 93 they were built for club racers with striped down interiors and limited options. The RS Americas were reputed to be Porsche’s fastest non turbo car of the time.

    I also had a 62 Ghia in college in the early seventies. At 40 hp not so scary fast.

    That makes more sense about the return being re-routed through the cool fuel given that out of the crate they were built for a return system.
     
  14. Espos4

    Espos4 Well-Known Member

    Jan 1, 2017
    Long Island NY
    2007 240 Sundeck
    350 MAG Bravo 3 W/DTS
    Yes, The CF3 setup has a dummy fuel pressure regulator on the rail. It doesn’t do anything.
     
  15. scoflaw

    scoflaw Well-Known Member

    Aug 10, 2011
    cape cod mass, cape coral fl
    1999 Powerquest legend 260 sx
    502 mpi Bravo 1
    Not true...it's a dampener for the fuel pulse.
     
  16. Espos4

    Espos4 Well-Known Member

    Jan 1, 2017
    Long Island NY
    2007 240 Sundeck
    350 MAG Bravo 3 W/DTS
    I Should have said it doesn't regulate fuel pressure.
     
  17. William Miller

    William Miller Member

    186
    Mar 16, 2007
    Darnestown, Maryland
    290 AJ
    Twin Mercruiser 300 hp Bravo III
    Dampener?
    It's between the pressure side of the rail and the capped return side.
    Does fuel compress?

    I was visiting some family for Independence Day.
    They have a lake boat with a 5.0 Volvo Penta 2008 model.
    It has the same exact intake. (Except its Red)
    I took some pictures which i'll post later.
    Also went to his dealer which was nearby and took a screen shot of the parts diagram and part numbers. Not that the numbers will cross reference......

    The return line is used and there is no additional regulator on their fuel modual.

    The only thing I have to work out is some fuel lines.
    Next is what might kiil the deal is to reconcile the fuel pressures.
     
  18. Henry Boyd

    Henry Boyd Well-Known Member GOLD Sponsor

    Apr 24, 2007
    Newburyport, on the peaceful and serene Merrimack
    ‘09 Sabre 38 Hardtop Express “Serenity”
    Volvo D6 w/IPS450 Pods
    Fuel is incompressible in practical terms, but it is under pressure. During acceleration fuel demand will cause pressure to drop and afterwards it spikes back up. The return "valve/regulator/gizmo" mitigates the pressure surges.
     
  19. William Miller

    William Miller Member

    186
    Mar 16, 2007
    Darnestown, Maryland
    290 AJ
    Twin Mercruiser 300 hp Bravo III
    webber 25.jpg webber pr 25.jpg webber pr 25.jpg
     
  20. William Miller

    William Miller Member

    186
    Mar 16, 2007
    Darnestown, Maryland
    290 AJ
    Twin Mercruiser 300 hp Bravo III
    This is the Weber regulator on top of cool fuel 3.
    What are the markings / specifications?
    I assume kpa is pressure.
    Is that RPM 10 Is there a symbol that looks like an "R" that refers to flow?
     

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