ISX15 CM2250 LOW PRESSURE FUEL

[Captain Donny]

Any ideas why the low pressure fuel is excessively high? Cummins spec is 145psi at high idle..

I'm at 225psi at the filter head test port. I also tried bypassing everything (cooler plate, filter and filter head) and still same readings. I jumped from my lines from the gear pump outlet to the high pressure pump inlet.

How else can I approach this problem without throwing parts at it?

[GhostHauling]

You’ll need to start a new topic so everyone sees your post to give you some help, i definitely don’t have any idea what’s causing your issue maybe a clogged filter.

[Rawze]

(06-01-2022 )Captain Donny Wrote:  Any ideas why the low pressure fuel is excessively high? Cummins spec is 145psi at high idle..

I'm at 225psi at the filter head test port. I also tried bypassing everything (cooler plate, filter and filter head) and still same readings. I jumped from my lines from the gear pump outlet to the high pressure pump inlet.

How else can I approach this problem without throwing parts at it?

you say it is a CM2250 engine...

Low pressure fuel codes are nothing at all to play around with on an common rail ISX. If the fuel pump is failing internally, it can destroy the entire engine in only a few days or so. Because of this, the first thing to do is pull the pump head off and inspect/test the guts of the fuel pump.

Also, if the pump has more than 400k miles or more than 8,000 engine hours on it then the pump needs to be pulled apart and all of its guts replaced any ways.. regardless of how they look.

-- next, is to ensure the engine passes a fuel rail leak-down test, as specified in this video ...
ref: http://rawze.com/forums/showthread.php?t...2#pid69262

[tree98]

Are you sure your gauge is reading correctly?

[Rawze]

and are you sure it is a CM2250?.. what is the engine ser#?.

[Captain Donny]

I looked up the ESN on Insite, but the engine serial number is 79614064. But yea the gauge is correct and I also double checked it with another gauge just to be sure. @Rawzw I don't have any faults and as far as I remember my high pressure fuel system is running within command pressures. My (Low Pressure) gear pump is pumping at 225psi at the filter head test port, seems excessive to me..

I also already checked the high pressure pump inlet screen which is okay

[tree98]

So what's the actual problem your having?

[windowrattler]

Looking through the service manual they are using a 0-300 psi test gauge and they have it as 145 psi minimum but don't list anything for a max psi for the transfer pump.

[Captain Donny]

@tree98 excessive pressure on my low side, but truck runs fine and no faults. I had a bad high pressure pump head and a priming pump 3 months ago, which I already repaired. I noticed the excessive pressure on the low side while testing the other problems