Diesel fuel pump failures

skijlw · 04-21-2019, 12:04 PM

I recently read some articles about diesel fuel pump failures in GM trucks newer than 2011 and also Ford diesels. The articles state GM and Ford use a CP4 high pressure fuel pump that has a high failure rate. The cost of this failure of the pump results in a repair bill in excess of 8,000 dollars. The solution is a replacement pump CP3 at a cost of 3500 dollars. There are a few class action suits against the manufacturers for repair bills as the CP4 pump was just a cost savings measure. The failures are stated to happen in the 100,000 mile area. My question is how frequent is the failure rate? I have not found any stats on failure rates. Have many of you diesel owners passed the 100K mileage mark and have any of you had this pump go bad? Many of you have RV friends that might have input. There is a good article about this pump in the recent Trailer Life magazine.

jimp · 04-21-2019, 01:35 PM

This issue was mentioned in the latest TrailerLife magazine in one of the Q&A sections. May be some additional info there.

**norty1** · 04-21-2019, 01:49 PM

Not sure if you want info on older ones. Mine died at a stop light 2 years ago. My truck is a 6.0 from 2006. Just stopped running. Cost 2k parts and labor to replace. It had over 100k miles on it. Still perking along.

Iraqvet05 · 04-21-2019, 02:20 PM

We had a high pressure pump fail on a 6.4 F-350 truck at work. The truck had 76k miles on it and the pump replacement was $4200,parts and labor.

TxLoser · 04-21-2019, 02:31 PM

If you go to any of the GM forums, you can find lots of info on this. There’s very little rhyme or reason as to the cause of the failure beyond ethanol maybe. It’s not really a sky is falling type issue, but always a possibility. Like a blow out on the highway. If I still have my truck after the warranty expires, I may get a cp3 conversion. Then again, I read a lot of stories where people get that done and then have other issues.

TCNashville · 04-21-2019, 08:42 PM

Quote:

Originally Posted by TxLoser

If you go to any of the GM forums, you can find lots of info on this. There’s very little rhyme or reason as to the cause of the failure beyond ethanol maybe.

I did not know they put ethanol in diesel fuel. Most CP4 failures are the result of water in the fuel.

**Midnightmoon** · 04-22-2019, 04:44 AM

That's the line that Ford has given for their CP4 failures. GM has been a lot more forthcoming to admit the design issues with the pump and have been much better at replacing them under warranty.

For you Ram guys, the CP4.2 is coming starting with the 2019 trucks. There are a couple of aftermarket companies already working on a CP3 conversion.

TxLoser · 04-22-2019, 10:58 AM

Quote:

Originally Posted by TCNashville

I did not know they put ethanol in diesel fuel. Most CP4 failures are the result of water in the fuel.

Not ethanol. Not sure what I was thinking. I meant the sulphur content. Basically the make up of our diesel we have here. The USLD diesel. I guess it doesn’t lubricate as well. Causing the pump to tear itself up. Or so I’ve read. And water too.

mikensue · 04-22-2019, 03:58 PM

Got 197000 on my 6.7 Ford...still running strong...

ricemanwm · 04-22-2019, 04:22 PM

This discussion is always a hot topic on the Duramax forums. A quick search and you’ll have more information than you would ever want. Just my observation on these forums is trucks that have modifications to increase performance tends to be the ones failing the most. I have a stock truck with the CP4 and I don’t plan on changing to the older CP3 pump.

**Midnightmoon** · 04-22-2019, 04:43 PM

Quote:

Originally Posted by ricemanwm

This discussion is always a hot topic on the Duramax forums. A quick search and you’ll have more information than you would ever want. Just my observation on these forums is trucks that have modifications to increase performance tends to be the ones failing the most. I have a stock truck with the CP4 and I don’t plan on changing to the older CP3 pump.

The CP4 is capable of making the same pressure with less volume of fuel than the CP3. Unfortunately, the fuel is what lubricates and cools the pump. On a modified truck, where you are trying to maximize rail pressure, the CP4 can quickly be incapable of enough flow to maintain the fuel volume to keep itself safe. That's why you are seeing many more failures on modified trucks.

With that said, the CP4 and even CP4.2 is subject to these failures even on stock trucks. You may reduce your chances in stock form, but it doesn't eliminate them.

I've had the opportunity to have the CP3 and CP4 side by side on a bench quite a few times. There is no comparison between the two. The CP3 is a much more robust design and there is no doubt why the CP3 is so much more expensive of a unit.

goducks · 04-23-2019, 09:58 AM

The CP4 was the reason I went with a Cummins in 2012. That was about the time that Ford was having a lot of problems with it. Had my 12 CTD for 6 years and no CP3 HPFP issues.
I've read that the new Fords have a different style HP4.

TWP723 · 04-23-2019, 11:08 AM

We sold 5 6.7 HPFP's in 2018 and 1 this year.

**JFlightRisk** · 04-23-2019, 11:20 AM

I haven't read a lot about these failures, in fact (not owning one) the article in Trailer Life was the first I've heard of it. My personal take on the article was NEVER let your fuel tank level get extremely low, or run out. As soon as there's air in the pump, the lubrication ceases, and the cam and rollers in the pump self destruct, and can take out the injectors with it. I passed the info along to my BIL, who has a 2014 GMC Duramax. This was good info to know.

vrader · 05-01-2019, 01:02 PM

Quote:

Originally Posted by Midnightmoon

The CP4 is capable of making the same pressure with less volume of fuel than the CP3. Unfortunately, the fuel is what lubricates and cools the pump. On a modified truck, where you are trying to maximize rail pressure, the CP4 can quickly be incapable of enough flow to maintain the fuel volume to keep itself safe. That's why you are seeing many more failures on modified trucks.

With that said, the CP4 and even CP4.2 is subject to these failures even on stock trucks. You may reduce your chances in stock form, but it doesn't eliminate them.

I've had the opportunity to have the CP3 and CP4 side by side on a bench quite a few times. There is no comparison between the two. The CP3 is a much more robust design and there is no doubt why the CP3 is so much more expensive of a unit.

and from all my research this is why I just added a FASS lift pump to my 2008 even though it has the CP3. This is combo upgrade to provide cleaner fuel to the injectors and reduce the stress on the CP3 and minimize the chance of a micro-vacuum leak with the stock set up (which is all it takes to get a low RAIL pressure code and be thrown into limp mode, which happened to me twice travelling across the country and horrible), AND I add Stanadyne Performance Formula Diesel Fuel Additive (per my mechanics recommendation to improve lubricity which by all accounts has diminished (why?) in today.s diesel fuel. Just added the lift pump and doing nothing to increase HP just run more efficiently so we shall see.

sgrol50 · 05-01-2019, 01:03 PM

Another consideration is that GM does not use a boost pump ahead of the HP pump (as of 2015). Ford does. You can help your HP pump by installing a FASS or Air Dog pre HP pump. Dodge junk had this problem several years ago with the solution being a boost pump pre HP pump.

vrader · 05-01-2019, 01:08 PM

What is "HP pump"? Yes no pump that I've heard of GM to provide positive pressure, just the suction from the CP3, or 4...

**JFlightRisk** · 05-01-2019, 01:20 PM

"HP" is for high pressure.

sgrol50 · 05-01-2019, 01:25 PM

Quote:

Originally Posted by vrader

What is "HP pump"? Yes no pump that I've heard of GM to provide positive pressure, just the suction from the CP3, or 4...

And that is bad.

oldmanAZ · 05-01-2019, 01:33 PM

Quote:

Originally Posted by vrader

snip...
I add Stanadyne Performance Formula Diesel Fuel Additive (per my mechanics recommendation to improve lubricity which by all accounts has diminished (why?) in today.s diesel fuel.
...snip

Not at all the same engine, but I've ALWAYS added Ford's PM-22A every time I add fuel; cetane increase and lubricity.

Lubricity of diesel has decreased because of the removal of sulfur. Why was sulfur removed...
'ULSD (ultra low-sulfur diesel) is a cleaner-burning diesel fuel that contains 97% less sulfur than low-sulfur diesel (LSD). ULSD was developed to allow the use of improved pollution control devices* that reduce diesel emissions more effectively but can be damaged by sulfur.'

(* Those devices = particulate filters & DEF. My 2006 doesn't have those and my fuel system and injectors were not designed with ULSD in mind nor the various 'bio-diesel' blends. So, IMO, I MUST use an additive to try to protect my engine.)

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