I’ll have to read more about the fuel system sometime. If what you say is accurate, then my lift pump circuit might have an issue. Since I’m only at ~20,300mi, I’ll just be letting it go until they do the recall on the cp4.
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Recall of High Pressure Fuel Pump
- Thread starter bill-e
- Start date
Rebelguy2020
Ram Guru
I have over 40,000 miles on my Rebel, some have way more than that without pump issues, if you had a bad lift pump your truck would not run.
Yeah it’s not a bad pump- I was referring to whatever allows air to bleed. I should not have had enough air trapped to cause extended cranks three times. If what you mentioned was working correctly, my thinking is that I shouldn’t have had any. The truck has been running fine for a couple weeks, so hopefully it stays that way. My trade-in plan is shot until at least the end of next year with how volatile the market is.
Rebelguy2020
Ram Guru
I found an image to simplify my explanation, after a fuel filter change, the low pressure electric lift pump in the tank fills the yellow lines and the fuel filter housing, all the air is bled to the tank, it is a good idea to let the ignition on for a minute without starting the engine to allow the low pressure lines and filter to fill and let all the air out. It’s important not to try to start the engine until the low pressure system is filled, if it’s not bled the high pressure fuel pump will starve and can cause cavitation resulting in possible damage.
The high pressure red lines will not fill until the engine is turning, the pump is gear driven, the engine will turn until the red lines and rails fill up to the injectors, that’s why the engine turns for so long before starting, the pump is not starving, it just takes time for all the air to bleed out.
c3k
Ram Guru
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Is there a one-way check valve between the boost pump and the HPFP? If so, that may be leaking, allowing fuel to drain back into the tank after shutdown.
I don't see it on that diagram...but that doesn't mean there is/isn't one there.
I don't see it on that diagram...but that doesn't mean there is/isn't one there.
On the Cummins, the procedure (meaning the manual and well known by most experienced diesel owners) is to cycle the ignition 3-4 times without starting to pressurize the fuel system and purge air after a filter change.
c3k
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Similar with VW TDi. Fill the fuel filter canister with fuel (as much as possible), then seal it up. Next, use a AlphOBD type system and run the boost pump for several minutes. This purges air.
For my Ram, when I changed the fuel filter (I did this after just a few thousand miles just to make sure any production crap in the tank/lines was removed), I selected "start" (without my foot on the brake), 3 times, for a minute each time. The truck fired right up after that, indicating that any air introduced by the filter change had been successfully purged.
That type of "cycle the pump" should be in bold letters in the owner's manual.
Edit: Here's our procedure. I did it 4 times. It doesn't mention anything about extended cranks but does mention running erratically (which wasn't an issue for me).
Here's the generic operation:
Our lift pump circuit's supply goes though the fuel/water separator (pic below) and to the cp4.2 hpfp. The lift pump gives as much fuel as it can (constant volume), and whatever is not used for fuel and lubing the pump is returned to the tank from the cp4.2 return line. This means there's no separate return circuit- air will get to the hpfp in some amount.
Last edited:
Rebelguy2020
Ram Guru
Rebelguy2020
Ram Guru
I should add something, replacing the fuel filter will drain the low pressure side and is easily primed by cycling the ignition a few times as said in members posts. If someone was to run out of fuel it would empty both low pressure and high pressure system, and would likely require more engine cranking before the system purges all the air out.
It's called the cascade overflow valve, and it's on the hpfp itself. It operates when the engine is on/hpfp is running. Now that I've started giving attention to this, I'll be doing a deep dive into the system.
Rebelguy2020
Ram Guru
Found this CP4 image
Edit: nevermind, need to read more to be sure of what I was going to say.
tom318
Well-Known Member
For those that have had fuel pump failures, were there any signs of any issue prior to failing? Poor fuel economy, power loss, anything? I'm talking the days leading up to the failure. I know some things may be small and looked over but then looking back after a failure it may make sense. I guessing there were no signs and it just failed but just wanted to ask.
2021EcoDiesel
Active Member
So, I called my dealer and they were able to schedule for the repair on February 8th of 2023. There wasn’t any mention as to whether there would be a large wait for parts or anything like that. Here’s to hoping the issue is resolved quickly.
Has anyone had this recall repaired?
Has anyone had this recall repaired?
Rebelguy2020
Ram Guru
Usually there is a second notification sent to all owners with a standing recall, saying parts or programming is available and it asks the owners to schedule an appointment to get their vehicles corrected.
Did you get a notification?
2021EcoDiesel
Active Member
I did not receive a notification asking me to contact the dealer yet, but the service manager at my dealer and I have a good relationship. I asked him about the recall and he said they have replaced a few pumps already so I just asked if we could set up an appointment and he said yes.
Rebelguy2020
Ram Guru
My dealer and I also get along well, even though I purchased my truck in Toronto, 8 hours south of my home, my guess is that your dealer is hoping a fix will be available by the time your appointment is up. I find that it should not be a hard fix because the trucks built after July 2022 are not affected, you would think, simply put the new components in the affected vehicles.
On the pump repairs, did your dealer simply replace the same pump or did they install the new components of the July 2022 production trucks? I did ask my dealer about the recall and they said not one vehicle came in for pump failures, I realize we are a small town, 45,000 population and maybe another 20,000 with all the surrounding much smaller municipalities, so not that many diesels were sold compared to Toronto and surrounding areas with a population in the millions.
2021EcoDiesel
Active Member
RebelGuy2020, I'm gonna give him a call sometime this week just to confirm, but from what he told me, the recall is only on the pump, a Bosch CP4.2 (please correct me if I'm wrong.) He didn't say it was a different pump, just one manufactured outside the window of error they have discovered. So I'm thinking it may come direct from Bosch or possibly from the Sterling Heights Ram Truck plant in Michigan.
