Hello everyone I NEED SOME HELP.

[Lonestar10]

At the end of the injector feed rail "the end of it closest to the front of the truck" there is a overpressure safety valve that tends to go bad the way you can check this is pull the banjo bolt out and run the injector leak test and when it's at full pressure see if fuel is coming out of the valve sometimes you will get fuel coming up from the banjo fitting so you might want to have a bucket or a pig mat underneath that area in case it does.

I've had to replace two of them in about 3 years and just a little dribble coming out of it can cause a fuel pressure drop under full load.

If this is bad I would recommend loosening and draining the fuel pressure off of the rail through one of the injector feed lines versus just taking the over pressure valve off this will bleed any high pressure out of the system.

Take caution while doing this test as the rail is around 30,000 PSI if that type of pressure comes out of that over pressure valve it can inject you with diesel and kill you so beware your surroundings anytime working on a high pressure fuel system that is open or leaking the same goes if you pull the injector feed lines.

[Nhramember]

(10-29-2023 )Bengy88 Wrote:  Is it only the 2343? It’s not accompanied by a 559 is it?

Hey bengy I had the exact codes. I replaced fuel pressure relief valve and still getting the codes. Any ideas

[Rawze]

(11-08-2023 )Nhramember Wrote:  

(10-29-2023 )Bengy88 Wrote:  Is it only the 2343? It’s not accompanied by a 559 is it?

Hey bengy I had the exact codes. I replaced fuel pressure relief valve and still getting the codes. Any ideas

is this a common rail ISX??.
How many miles/hours since the fuel pump was last rebuilt?.

ref: http://rawze.com/forums/showthread.php?t...9#pid61019

[Nhramember]

I replaced the housing and brand new tappets etc. I didn’t do the head. I have replaced the fuel filters 3 times put clear diesel in the tank .I have filled up 3 or 4 times since the biodiesel and ran treatment at least 3 times, I’m going crazy with this no more biodiesel ever.

[Nhramember]

Replaced it in summer2022. I replaced the housing and new tallest etc.

[Rawze]

I seriously do not think that typical B15 or B20 commercially sold biodiesel would have caused your issues. Maybe bad fuel or something, but the typical truck stop/fuel station B20 mix is not going to cause problems normally.

[Nhramember]

Do you think filter housing?

[Nhramember]

I have replaced fuel rail pressure relief valve,fuel filter 3 times, water separator filter too. I have pics of the fuel from the tank. Where do u think it could be ?

[Smooth]

From Reading the previous , The next step would be checking each injector for leaking Cups.

There may be an easier way to do this if there is I do not know of it.

Cummins Quickserve - Go to Troubleshooting of 559

You would need Set of Injector Block-Offs
You are also going to need certain test fitting from Cummins.
Maybe you can borrow these items if not they do add up to a bit of $$$ but worth the money if you can perform these tests yourself in comparison to what a dealership that may of may not do things properly will charge you.



Quickserve will give you step by step of the process.

Leak Isolation Test.

But There are many tests involving Code 559 and it can be a bit overwhelming and time consuming.

But seems you have already made the most commons moves and yet to find your problem. I would suggest Quickserve and starting at the beginning of 559 Troubleshooting.

Unfortunately w 559 There is rarely a fast easy solution. 1 of many reasons why I prefer and CM871