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sprinkles08, Chrysler/Dodge/Jeep master tech
Category: Dodge
Satisfied Customers: 22648
Experience:  ASE Master and Advanced Certified, Chrysler/Dodge/Jeep Master Certified, Trans and Hybrid Specialist
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I have a 2005 ram 2500 diesel and have recently been

Customer Question

Hi i have a 2005 ram 2500 diesel and have recently been experienceing what feels like slight surging at hwy speeds in my truck.When i hook up my diagnostic reader and drive it it will fluctuate in fuel rail pressure. Is this fluctuation a normal thing?The pressure fluctuations at hwy speeds are between 118,000 kpa and 125,000 kpa.I am think i have good supply from fuel tank to CP3 pump as i have just recently had a FASs 150 installed.Any thoughts ?
Submitted: 9 months ago.
Category: Dodge
Expert:  sprinkles08 replied 9 months ago.

Hello and welcome to Justanswer!

Some fluctuation is normal but actual pressure should stay within 500 PSI of setpoint. If it goes higher or lower than setpoint by 500 PSI then you either have a fuel delivery issue, a problem on the high pressure side or a bad fuel control actuator.

Are any fault codes setting?

Customer: replied 9 months ago.
There are no fault codes, i have ohm'd out each injector, tested each injector wire harness. They are all fine. I am thinking the same thing also. Perhaps fca or rail pressure sensor. Or finally a CP3 on the way to failure.
Expert:  sprinkles08 replied 9 months ago.

I've never seen a high pressure pump fail, it's most likely ok.

Was pressure going more than 500 PSI from setpoint?

Customer: replied 9 months ago.
I have my code reader diag hooked up, truck is up to temp. I have arrived at work this morning. Parked and have the truck idled up to 1500 rpm.My fuel rail pressure is fluctuating from 8800 psi up to 9250 psi.Idled at 1100 rpm 7600 psi up to 8150 psi.Then with idle control off fluctuation is 6515 psi up to 6945 psi
Expert:  sprinkles08 replied 9 months ago.

But is the driveability issue happening presently? That's when you need to monitor pressure.

Customer: replied 9 months ago.
While travelling at Hwy speeds i do see the same relative fluctuations, cruising at 60-65 Mph i can feel the slight surge as if the truck is slightly surging forward then slightly easing off. There isn't any huge driveability i will monitor it again later today.thx for the assistance.any little hints or things to check from your experience is appreciated.
Expert:  sprinkles08 replied 9 months ago.

When the problem is happening while driving is when you need to be monitoring data. A helper will most likely need to drive the truck while you monitor actual pressure versus setpoint.

Customer: replied 9 months ago.
Ok thx
Expert:  sprinkles08 replied 9 months ago.

You're welcome!