Logo
Click forPleasurecraft Marine parts and manuals!
Results 1 to 22 of 22
  1. #1

    Default Fuel Pressure PCM

    I have a 2002 PCM (350 HO) in my MB Sports Tournament Ski Boat. Hours are 792.

    I'm reading 30psi off the Shrader valve on the Fuel Control Cell. That seems a bit low to me.

    What should the continuous pressure be?

    Also, with key turned on, engine not started, the pressure will rise to 30psi and then fall to zero. But starting the motor, raises the pressure to 30psi again, where it stays.

    Shouldn't the pressure stay at 30psi even if the engine isn't running as long as the key is on? Or is the engine computer intervening somehow to determine if the engine isn't running?

    thanks,

    RickR90s

  2. #2
    Join Date
    Sep 2008
    Location
    Maryland - USA
    Posts
    6,824

    Default Re: Fuel Pressure PCM

    going off memory, I'd say you are correct....think more like 50 psi.....you should check the service manual to be sure!!

    It may be designed to fall to zero, but very slowly....if its a rapid drop, then something in the fuel system is leaking - again, the service manual can fill in those voids.

    The computer usually 'primes' the fuel circuit for startup....and then turns the pump on once it determines the engine is running....the fuel pump needs to maintain the spec PSI all the way up to WOT...if not, performance will suffer.

  3. #3

    Default Re: Fuel Pressure PCM

    thanks makomark,

    the pressure is maintained up to WOT, just seemed a little low to me. I have the service manual so I'll check that out. thanks,

  4. #4

    Default Re: Fuel Pressure PCM

    This past weekend I was winterizing the boat. So I wanted to start it up to get the oil warmed prior to changing. The same fuse kept blowing again.

    I'll address it further in the spring by further testing each pump. (low pressure and FCC)

    thanks,

    Rick

  5. #5
    Join Date
    Sep 2008
    Location
    Maryland - USA
    Posts
    6,824

    Default Re: Fuel Pressure PCM

    may be a bad connection in the circuit(s) protected by the fuse....especially on the ground side....a voltmeter can be used to check for voltage drops across the connectors...an IR gun can be used too but doesn't always show the issue...

  6. #6

    Default Re: Fuel Pressure PCM

    hi Makomark,

    That's something I considered and will look at next spring. I have the PCM schematic so I sort of, kind of, have a place to look for that condition.

    I am concerned about the low FCC pressure though. It was only 30 psi, so I'll be looking at both high pressure and low pressure pumps in the spring.

    thanks,

    RickR90s

  7. #7
    Join Date
    Jan 2010
    Location
    Posts
    922

    Default Re: Fuel Pressure PCM

    2002-2003 Engine MODEL MP 5.7L (330 HP)
    Displacement 5.7L (350)
    Fuel Pressure 55-62 psi
    See page 52 +/- for more engine specifications, http://www.planetnautique.com/Correc...s%20Manual.pdf

    This engine is said to have a high and low fuel pump. Typically the first thought with fuel pressure dropping quickly to 0 would be the fuel pressure regulator but if you seem to be blowing a fuel pump fuse then that would tend to indicate more of an possible internal issue within the fuel pump such as a bad motor and/or stuck internal check valve...If not then possibly a power and ground issue within the wiring circuit someplace.

    Have a read on page 34+ while your in the owners manual linked above too.

  8. #8

    Default Re: Fuel Pressure PCM

    Thank you sir!

  9. #9

    Default Re: Fuel Pressure PCM

    I do suspect the low pressure pump as the screen was plugged when removed recently.

  10. #10

    Default Re: Fuel Pressure PCM

    Good afternoon everyone. So good to see Spring around the corner. So I picked up my boat today out of storage and replaced the low pressure and high pressure pumps (fuel control cell) as well as the FCC filter. If you recall last fall, I winterized the boat but the fuel pump fuse kept blowing.

    I also installed an inline fuel filter between the low pressure pump and the fuel tank.

    The boat started fine, and no blown fuses, but checking the fuel pressure at the FCC Shrader connector shows about 33 psi, when specs say it should be 55-62.

    Am I missing something here? To the best of my knowledge, there isn't fuel pressure regulator.

    Appreciate the help,

    Rick

  11. #11

    Default Re: Fuel Pressure PCM

    Since this engine uses a dual venture throttle body, does it even have a fuel pressure regulator?

    Thank,

    Rick

  12. #12

    Default Re: Fuel Pressure PCM

    Since this engine uses a dual venturi throttle body, does it even have a fuel pressure regulator? If not, I assume fuel pressure is maintained by the FCC pump.

    Thank,

    Rick

  13. #13
    Join Date
    Dec 2015
    Location
    maplevalley WA
    Posts
    3,541

    Default Re: Fuel Pressure PCM

    Could be a couple things a check valve in the fuel pump allowing fuel to bleed back into the fuel tank or leaking injector/s. Is it hard starting like it is flooded?
    It takes a nickle to go first class!
    If it aint broke dont fix it!!

  14. #14

    Default Re: Fuel Pressure PCM

    It starts and appears to run perfectly fine. (in the driveway anyway). I'm just wondering if the fuel pressure is a little low.

  15. #15
    Join Date
    Sep 2008
    Location
    Maryland - USA
    Posts
    6,824

    Default Re: Fuel Pressure PCM

    If you have new pumps and the pressure is low, I'd think the regulator would be the next item to check....if the pressure is the same with the previous pumps, then they are likely still serviceable.

    BTW, its likely to run fine in the driveway....the pressure really needs to be checked under load. if the pump won't maintain pressure at WOT the issue still isn't resolved.

  16. #16

    Default Re: Fuel Pressure PCM

    Quote Originally Posted by makomark View Post
    If you have new pumps and the pressure is low, I'd think the regulator would be the next item to check....if the pressure is the same with the previous pumps, then they are likely still serviceable.

    BTW, its likely to run fine in the driveway....the pressure really needs to be checked under load. if the pump won't maintain pressure at WOT the issue still isn't resolved.
    I guess my question is whether the system has an additional fuel pressure regulator. I don' believe so because it's a throttle body system, not multi-port where there are 8 individual fuel injectors AND a fuel regulator on the fuel rail.

    Rick

  17. #17
    Join Date
    Sep 2008
    Location
    Maryland - USA
    Posts
    6,824

    Default Re: Fuel Pressure PCM

    Ok....the link provided earlier in the thread is for the MPI version....if you have a TBI unit, that's not the correct manual....I'd suggest first off, getting the serial number from your engine and then getting the correct spec - the factory help line is the best if you dont have a local dealer....you mentioned earlier you have the factory data - make sure it is correct for what you have...

    The MPI systems run higher than the TBI version.....and the TBI stuff had a very short time....so parts are not common or cheap. The late 90's merc spec for TBI is 30 psi so you may be ok there (if you have the TBI), provided it is help across the load range.

    Finally the GM TBI system has a regulator inside of it.....the only ones I've seen that don't were custom mods where an external unit was used.

  18. #18

    Default Re: Fuel Pressure PCM

    Mako, Thanks so much for your expertise. I'll contact a PCM rep, but I believe also that 30+ psi is going to be fine for a throttle body system. I drop my boat in this week, so I'll be checking the fuel pressure at full throttle.

    Kindest Regards,
    RickR0s

  19. #19
    Join Date
    Mar 2009
    Location
    Portland, Oregon,
    Posts
    9,189

    Default Re: Fuel Pressure PCM

    I think that Mark is giving you spot-on info.

    Quote Originally Posted by RickR90s View Post
    I also installed an inline fuel filter between the low pressure pump and the fuel tank.
    Rick, the in-line fuel filter media is far too small, and if this is the plastic body style, they are not legal in a marine application.
    You will want to install a canister style fuel filter system. RACOR (w/ the metal bowl for inboards) is one of the best out there.



    .
    Rick ... aka Ricardo..... AQ series Volvo Penta repair
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

    Please... no PMs! Post your questions on the forum.

  20. #20

    Default Re: Fuel Pressure PCM

    Quote Originally Posted by RicardoMarine View Post
    I think that Mark is giving you spot-on info.



    Rick, the in-line fuel filter media is far too small, and if this is the plastic body style, they are not legal in a marine application.
    You will want to install a canister style fuel filter system. RACOR (w/ the metal bowl for inboards) is one of the best out there.



    .
    Hi Ricardo, I believe I did just that. I got the metal style unit from Miami Nautique, as they sell parts for PCM applications.

    I was thinking I would get a glass, style unit so I could view when to change it or clean it, but Miami Nautique advised the same as you.

    Thanks for the info.

    Rick

  21. #21
    Join Date
    Mar 2009
    Location
    Portland, Oregon,
    Posts
    9,189

    Default Re: Fuel Pressure PCM

    Just for you....... har har!
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	Racor vs in line .jpg 
Views:	16 
Size:	39.6 KB 
ID:	15180  
    Rick ... aka Ricardo..... AQ series Volvo Penta repair
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

    Please... no PMs! Post your questions on the forum.

  22. #22

    Default Re: Fuel Pressure PCM

    Everything working fine so far.

Similar Threads

  1. 2008 Optimax 225 VST Side fuel rail getting no fuel pressure??
    By 25donzitwinoptimax225s in forum Fuel Gas Oil Mixture Ratio
    Replies: 0
    Last Post: 07-31-2016, 08:26 AM
  2. fuel pressure
    By oldvet in forum Johnson Evinrude Outboard Forum
    Replies: 1
    Last Post: 06-12-2014, 11:06 PM
  3. High pressure fuel pump putting out to much pressure
    By Bluecollerboater in forum Volvo Penta Gas Engine Forum
    Replies: 1
    Last Post: 06-25-2013, 12:45 PM
  4. What should the fuel pressure be on a high pressure fuel pump?
    By Bluecollerboater in forum Volvo Penta Gas Engine Forum
    Replies: 0
    Last Post: 06-20-2013, 04:09 PM
  5. to much fuel pressure
    By hellfire in forum Johnson Evinrude Outboard Forum
    Replies: 0
    Last Post: 08-25-2012, 10:21 AM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •