Code 4726

[Bama Boy]

looking for help on how to test fuel pressure relief valve and injectors on CM2350.

[Bama Boy]

I have insight and did fuel leak down test, and pressure falls very rapidly

[Rawze]

if the pressure relief valve is more than a couple years old, you could replace it and see if it passes the leak test again.

[Mr Hagg]

Ok so we remove banjo bolt and take a place a bolt the same size as the banjo bolt and use washers and the ones that come off the banjo bolt tighten it up and then start truck see if you see ANY fuel dripping out its bad... Then with insight run up fuel pressure through the fuel pressure leak down test... Onces it reaches 29000 turn truck off and see if its leaking. If not then you will need to start capping off injectors one at a time. A few times I have found the injector connecting tube is the problem may have worked loosed or what ever. So before I throw a $1000 injector at it, I will inspect connector tube and clean and reinstall and torque to spec.... And try again... If that dont work then replace injector + a new connector tube. NOTE: the caps can be bought from any cummins dealer.. I have all 6 so you can cap off as many as needed....

[Bama Boy]

Thx! I will update results

[Bama Boy]

Well 1st dealer I stopped at had neither pressure valve or cap off nuts on down the road we go

[Mr Hagg]

Shoptalk
Possible causes of this fault code include:

Leaking fuel injectors and or fuel injector connectors

Leaking fuel rail pressure relief valve


So your on the right track

[Rawze]

(09-10-2020 )Bama Boy Wrote:  Well 1st dealer I stopped at had neither pressure valve or cap off nuts on down the road we go

that is pretty sad ... you would think the OEM repair facilities would at least have the right stuff for such a fairly common issue.

[Bama Boy]

K stopped at another dealer, got fuel relief valve for $132. Replaced myself. Leak down test inconclusive because computer kept disconnecting when i turn off engine. I reset code and riding to see if it comes back.