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I want to add a fuel pressure gauge to keep an eye on it. On my high pressure rail fuel system I think the lift pump that runs for 30 seconds feeds the mechanical fuel pump then goes to the fuel filter in the rear of the coach. On the line coming from the mechanical pump feeding the high pressure fuel pump am I correct that the pressure should be in the 70 psi range? I need to know so I can get the right gauge.

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On an ISC engine the sequence is fuel tank ->primary filter -> lift pump -> secondary filter -> CAPS / HPCR high pressure pump -> fuel injectors

The lift pump supplies about 15 psi of pressure to the HPCR fuel pump for ~ 30 sec.  After that the HPCR pump sucks fuel from the tank making a gauge a nice dash decoration after that . . . . unless you install a secondary pump like the FASS system. 

On an ISC engine most folks tap through an already a plugged hole on the top of the secondary fuel filter housing.  But the Countess has an ISL?

This is the adapter and gauge I used (ISC).  I barely had enough wire with the routing I took (38' Endeavor).  It's all in the routing.

gauge - https://www.amazon.com/gp/product/B007GDXK06/

adapter - https://www.amazon.com/gp/product/B00NWZBB0S/

harness - https://www.amazon.com/gp/product/B087SDJFRK/

mount - https://www.amazon.com/gp/product/B091C8X4HY/

Good luck,

- bob

Edited by cbr046
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cbr046 stated that correctly. I just finished my FASS install this week and have selected that same gauge setup that I will run up front. Thanks for the P/N for the extra wiring harness Bob, the other in the kit is only 9’ it says, I’ll just tie them together to reach up to the front. 

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Not sure on where/if you can tap into the pressure line/port of injection pump.  Might warrant a call to Cummins.  My guess is that there is a place as they probably have a way to read fuel pressures while troubleshooting problems.  Might be as simple as removing a plug and putting in a sending unit. 

 

I used all the same Glowshift parts except the mounting bracket, I bit the bullet and just mounted in my dash.  I like the ability to see the pressure when starting the rig and while driving.   I've put ~10K miles on the FASS system and filters since installing and am still holding ~16 psi at startup.   You'd know real fast if you have a problem with fuel problems and or FASS pump problems.

With the ~40' of extension I barely had enough to be able to only make one splice above the generator.  Worked great.

 

 

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1 hour ago, jacwjames said:

Not sure on where/if you can tap into the pressure line/port of injection pump.  Might warrant a call to Cummins. 

The gauges I listed won't nearly read that high!  If that's what the OP wants to do is it possible to read hi pressure fuel reading through the diag port, like through VMSpec, ScanGauge or similar ECM monitoring tool?

The setup I listed is the pressure feeding the injection pump.

- bob

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