Volvo Penta Fuel Cell Low Pressure Pump - Out of range?

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fognyc

Cadet
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Sep 12, 2016
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Setup:
  • 2004 5.7gxi-F 3869260 4012119425 Duoprop
  • 530 hours on the block (heavy overhaul as the engine was partially submerged during Hurricane Sandy.. Most parts new, but fuel cell original)
  • Used in brackish water
  • Religiously run engine with fresh water after every use.
Hi All,

I had the dreaded whine and substantial heat in my high pressure pump, and just bit the bullet and bought a whole new fuel cell. After I installed it, there was a definite improvement:

  • Hi pressure pump is cool
  • Have 50 PSI on the high side
  • No whining
  • Engine sounds good at idle
  • I can feel water moving through the cooling jacket of the cell and out the port riser

However there are still a few strange things:

  • At idle (in gear) my low pressure pump is 18 PSI (according to the manual it should be "8PSI +-2 at load")
  • At 2500 RPM under load the low pressure pump is 14 PSI
  • At 4000 RPM under load the low pressure pump is 10 PSI
  • At 4300 RPM under load the low pressure pump is 10 PSI
  • At WOT my max RPM is around 4300
you can see it here:
https://youtu.be/j5rVgDwcBJY


Before I swap out a different brand new pump (Dealer was quick to give me a new one free of charge), are these specs normal given that the service manual states that the low pressure pump needs to be "8PSI +-2 at load"? Parts guy was uneasy with it being 18psi in gear at idle.

Asking the group: Should I swap a new fuel cell in, or keep the current new installed one as these specs are seemingly in line because the readings are only relevant at significant loads? If 18psi is considered too high at idle (under load), Is there anything in my setup (outside of the new fuel cell) that could be causing the pressure to be that elevated?

Also, the WOT max of 4300rpm doesn't seem right either.. that could be end of season fouling of the hull (haven't used boat in the past month).. but if there is any thing you guys might suggest that would cause the seeming loss of power (considering the newly installed fuel cell), I'd really appreciate it.

Thanks!
 

bajaunderground

Lieutenant
Joined
Apr 18, 2008
Messages
1,401
(according to the manual it should be "8PSI +-2 at load")
[*]At 2500 RPM under load the low pressure pump is 14 PSI
[*]At 4000 RPM under load the low pressure pump is 10 PSI​<--
[*]At 4300 RPM under load the low pressure pump is 10 PSI ​<--
[*]At WOT my max RPM is around 4300


​Seems to me the 10psi is within the range as you listed "at load"? I'm not sure what the range is or the "load"?
 

fognyc

Cadet
Joined
Sep 12, 2016
Messages
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thanks Baja.. yes 10psi is in tolerance while under a full load at wide open throttle. My concern is 18psi at idle "in gear" a problem when it's 10psi at WOT? Can any experts confirm if this is safe? I could not find if this is acceptable.
 

fognyc

Cadet
Joined
Sep 12, 2016
Messages
8
Hi guys just bumping this to see if anyone had some specific insight on tolerances under load for the low pressure pump given so many of you had to have your fuel pumps replaced. I could really use the insight. thanks!
 

gbeltran

Petty Officer 1st Class
Joined
Jul 12, 2009
Messages
283
Is there a way you can just power the low pressure pump to get a reading? When that whole thing is energized whatever fuel that isn't getting used by the injectors or is over the regulator limit is bypassed back into that reservoir, which could add to the pressure reading on the low side. As far as your 4300 rpm, what was it before? Did this just start with the new engine? There is a service bulletin about the regulator on those engines, has it been done? (I've included it as an attachment)
 

Attachments

  • 156 PB P-23-7 N03 V01 Fuel Pressure Regulator.pdf
    34.2 KB · Views: 3

fognyc

Cadet
Joined
Sep 12, 2016
Messages
8
thanks Gbeltran!


yes that totally makes sense that more pressure would build up at idle/in gear because the lack of fuel demand. I could certainly disconnect the high pressure pump and see if that get's it closer to 8 +-2 psi.. I guess I'm just asking is 18psi at 600rpm while in gear simply fine (can anyone verify)? As for the the WOT limit, I'm pretty sure i've gotten close to 5k rpm earlier in the season. It's not a new engine, I've just recently put a new fuel cell in it. I have serviced the regulator with the e-clip too.

thanks!
 

Taz59

Petty Officer 1st Class
Joined
Apr 10, 2003
Messages
304
Hi bud
I have been having a nightmare with my Engine stalling at idle, low pressure pump pressure 18psi. High pressure pump pressure 54psi.Replaced the following
IAC Valve
Crankshaft Sensor
New Pressure Regulator with e-Clip fitted
Still stalling at idol
So decided to bite the bullet and buy a new fuel cell.
Runs fine now at idle
At idle low pressure pump is 10psi high pressure pump is 50psi

Cheers
 
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