Low block pressure but no codes

frenchshipfrenchship Member Posts: 1,079 ✭✭✭
Hi, Friend has Rinker 290 Fiesta Vee 2004 twin 5.0 MPI with Alpha stern drives . last weekend at Alexandria bay his alarm went on. So we put the Rinda code reader on but no codes register. We read some parameters the only thing that came out not normal was the block pressure at 1.8 on one engine the other read 7.4 both engines at idle. He just had the water pump replaced on this engine. From what I understand these alpha drives do not have a sea water pumps like the bravo 111. So any ideas on this. Funny that the rinda show no codes. Thanks Paul

Comments

  • frenchshipfrenchship Member Posts: 1,079 ✭✭✭
    Sorry just looked at mercruiser parts catalog it seems to have a sea water pump I guest that could be the problem.??
  • 212rowboat212rowboat Member Posts: 2,593 ✭✭✭✭✭
    the impellor on the lower unit serves sorta like a lift pump to the blocks circulation pump... which one was replaced? 

    i am trying to wrap my brain around how the engine monitors flow... to my knowledge, the is no way to determine flow without some fancy calculations, as it is not directly monitored... maybe based on engine temp and rate of increase or decrease could do it, but i would guess that cant be trusted very much.. 

    what kind of alarm did he get? was it steady tone, steady beep, or two beeps every 60 seconds? did he experience loss of power? has it persisted or is it now gone? 
  • 212rowboat212rowboat Member Posts: 2,593 ✭✭✭✭✭
    it makes sense there is no code because there is no way for the engine to monitor the flow the reader is calculating.... there could be a table reference based on rpm, engine rate of cooling/heating to determine this, but like i hinted above, there has to be some witchcraft involved to determine that, and i wouldnt trust it... :-) 

    cause and effect trouble shooting dictates that you reverse your course and see where the weak link exists... whichever pump was replaced is where i would start.. if the impellor, check it out.. that drift tube that flowers at the top would be easy to misalign, and if the engines circulating pump, check: 

    -the hoses for pressure (grab them.. you can feel flow)
    -the check valve at the junction..
    -the belt routing.. dumb mistake.. ive done it.. twice.. i am dumb.. :-) 
    -look for signs of weeping at the pump and every junction. 

    good luck, come back with more info, and or observations, and maybe we can dig deeper.. :-) 
  • Black_DiamondBlack_Diamond Member Posts: 5,439 ✭✭✭✭✭
    Good points from Drew. If it is not sensing pressure, then something is restricting inflow: bad pump, misalignment, plugged, etc. I'd start with the just replaced pump.

    Past owner of a 2003 342FV
    PC BYC, Holland, MI
  • frenchshipfrenchship Member Posts: 1,079 ✭✭✭
    Thank for the Infos. We where getting two beeps every 60 seconds with seems with no loss of power the code reader was saying 100% power availbe. If it was the block pressure sensor should we have code 37 on the code reader. The lower unit pump was replaced last week before our trip to Alexandria bay because the engine was overheating at full rpm. During our trip I don't remember that he went at full rpm. So for now I will ask him to go back today if possible and go to full rpm to see if he still has overheating with the new pump. And to check Drew suggestions By the way he was telling me that in some occasions the same engine while on the step would shut down and it would restart right away could it be related ? I will come back with the result later on. Thanks Paul
  • 212rowboat212rowboat Member Posts: 2,593 ✭✭✭✭✭
    I'm still trying to wrap my brain around a 'block pressure sensor', which I didn't know existed!! Now that I'm in front of a computer, I'm going to be researching those things... I'm fairly certain my rig doesn't have one.. :-)  Al, are these things only on engines with sea water pumps mounted in the engine bay?, as in, directly upwind of the sea water pump or near the outlet?

    Frenchship, check this link out: http://rinkerboats.vanillaforums.com/discussion/1042

    I threatened to do it, but haven't yet- I aim to laminate that code chart and keep it on board...I'm thinking it could get to be pretty handy..

    I've not encountered it, but I've been told this about lower unit impellers, and it makes sense: "they can't produce volume/flow at lower RPM's when they are going bad, but can at higher RPM's because of the added twirl".. so you would likely see a warmer engine at or off idle before you would see heat at higher RPM's if that holds true..

    the engine shutting down and easily restarting sounds to me like an electrical issue- a bad connection somewhere- maybe at the PCM, maybe a ground, maybe a hot lead to the battery or battery switch.. I'd start there on that issue, and only move the second family of possibilities once I knew beyond doubt those were eliminated.

    1.) Faulty cam,
    2.) IAC,
    3.) MAP,
    4.) MAT,
    5.) knock sensors.
    6.) open/short in the engine cooling temp circuit
    7.) open/short in fuel injector wiring circuit,
    8.) open/short in oil PSI circuit,
    9.) open/short in exhaust manifold cooling temp circuit,
    10.) open/short in sea pump circuit,
    11.) open/short in throttle position circuit
    - See more at: http://rinkerboats.vanillaforums.com/discussion/1042#sthash.Fc5r8PvT.dpuf

    1.) Faulty cam,
    2.) IAC,
    3.) MAP,
    4.) MAT,
    5.) knock sensors.
    6.) open/short in the engine cooling temp circuit
    7.) open/short in fuel injector wiring circuit,
    8.) open/short in oil PSI circuit,
    9.) open/short in exhaust manifold cooling temp circuit,
    10.) open/short in sea pump circuit,
    11.) open/short in throttle position circuit
    - See more at: http://rinkerboats.vanillaforums.com/discussion/1042#sthash.Fc5r8PvT.dpuf
    1.) Faulty cam,
    2.) IAC,
    3.) MAP,
    4.) MAT,
    5.) knock sensors.
    6.) open/short in the engine cooling temp circuit
    7.) open/short in fuel injector wiring circuit,
    8.) open/short in oil PSI circuit,
    9.) open/short in exhaust manifold cooling temp circuit,
    10.) open/short in sea pump circuit,
    11.) open/short in throttle position circuit
    - See more at: http://rinkerboats.vanillaforums.com/discussion/1042#sthash.Fc5r8PvT.dpuf
    1.) Faulty cam,
    2.) IAC,
    3.) MAP,
    4.) MAT,
    5.) knock sensors.
    6.) open/short in the engine cooling temp circuit
    7.) open/short in fuel injector wiring circuit,
    8.) open/short in oil PSI circuit,
    9.) open/short in exhaust manifold cooling temp circuit,
    10.) open/short in sea pump circuit,
    11.) open/short in throttle position circuit
    - See more at: http://rinkerboats.vanillaforums.com/discussion/1042#sthash.Fc5r8PvT.dpuf
  • 212rowboat212rowboat Member Posts: 2,593 ✭✭✭✭✭
    huh... the pressure sensor is located on the sea water pump on earlier models, and on the later it is located on the power steering cooler.. you learn something new every day, I reckon! :-)

    I'm guessing wildly here, but a two beep every sixty seconds could be an open/short in the sea pump circuit, and drop your power to 90% logic... it comes down to either a bad sensor ($80 and ten minute fix) or a failing sea pump- which costs a bit more, if that is the case..

    for what it's worth- a bad sensor will cause the reduction in power as easily as a bad pump will- but can likely be determined by engine temperature... if the engine is cooling like the other engine (as in they read near the same), it would indicate a leaning toward the sensor as opposed to the pump..

    Al, does this sound right?
  • Robyw1Robyw1 Member Posts: 56 ✭✭
    edited August 2013
    I am getting no alarms however on my SmartCraft SC-1000 gauge my pressure at idle is less than 1-PSI. (0.7 to 0.8). Should I be looking for a new pump for my 5.0MPI Alpha? My temperatures are at about 150 with no variance. At 2000 RPM and above it is running about 5 to 7 PSI.
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