Fuel rail pressure

[Awinkles208]

Just wondering if anyone else’s 6.7 cummins Rail pressure drops below 4K psi when they hit the brakes to stop from high mph? And should rail pressure fluctuate with Rpms when truck is downshifting thru gears to stop? If anyone can share there rail pressure during different conditions that would be great. Idle, when cruising at 55-60mph, and then when brakes are applied til complete stop.


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[TexNeck]

Just wondering if anyone else’s 6.7 cummins Rail pressure drops below 4K psi when they hit the brakes to stop from high mph? And should rail pressure fluctuate with Rpms when truck is downshifting thru gears to stop? If anyone can share there rail pressure during different conditions that would be great. Idle, when cruising at 55-60mph, and then when brakes are applied til complete stop.


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I wouldn’t think below 4K but will look on my commute tomorrow. At idle with DRD tunes I run 4300-4800psi at idle (in park or D with no throttle)

do you have any tuning? Which gauge are you using?

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[Awinkles208]

I do have tuning but not looking to drag the complexity of my issue into this, only to see what others see for rail pressure. I do not have ability to view desired rail pressure so that’s why I want to see others rail pressure in different conditions.


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[TexNeck]

I do have tuning but not looking to drag the complexity of my issue into this, only to see what others see for rail pressure. I do not have ability to view desired rail pressure so that’s why I want to see others rail pressure in different conditions.


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understood. I’ll report back tomorrow - maybe someone will chime in the meanwhile

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[Awinkles208]

Thanks I appreciate you!


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[CumminsOwner]

I also have a Rail Pressure question whats the highest it should get to? on my raceme ultra at 120hp setting it spiked at 28k psi is that normal?

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[TexNeck]

Thanks I appreciate you!


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43xx was the lowest I had mine drop to and it was a split second. I’d look into changing your fuel filter(s) and see if it improves.

what’s your psi at idle?

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[TexNeck]

I also have a Rail Pressure question whats the highest it should get to? on my raceme ultra at 120hp setting it spiked at 28k psi is that normal?

that’s normal with a healthy CP3.

If you plugged the Rail you may be able to get 1-2k more but that wouldn’t be worth the performance gain IMO.

If you have a weak PRV and pressure maxes at 24k then try plugging it.

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[CumminsOwner]

What would be too much RP?


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[cumminsdieselfreak]

What would be too much RP?


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Under normal conditions, 26k-27k plus is above normal range. You'll be around 4800'ish at idle, around 10k at cruising speed and around 24k-25k on WOT pulls.

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