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Gapvalley · 02-07-2023, **(Subject: Engine miss )**

Working on a 2015 Cummins cm2350 driver came in with a miss. Connected insite to truck found a active code 4726 engine fuel leakage not sure if this is my main issue or not. Cutout cylinders found cylinders 1,3,5 are missing. 2,5,6 make the engine change rpm. Pulled the valve cover off and started engine intake and exhaust valve are all moving and Jake rockers are not moving. Next step my be run a valve adjustment if there all within spec maybe ecm. Looking for any input

Rawze · 02-07-2023, **(Subject: Engine miss )**

(02-07-2023 )Gapvalley Wrote: Working on a 2015 Cummins cm2350 driver came in with a miss. Connected insite to truck found a active code 4726 engine fuel leakage not sure if this is my main issue or not. Cutout cylinders found cylinders 1,3,5 are missing. 2,5,6 make the engine change rpm. Pulled the valve cover off and started engine intake and exhaust valve are all moving and Jake rockers are not moving. Next step my be run a valve adjustment if there all within spec maybe ecm. Looking for any input

that is a fuel leak code.

will it pass an injector leak test?.. what was the leak rate in one minute.. when done exactly like this video shows. The test must be done at a full 30,000 psi to find all leaks, and not just at idle pressures.

https://odysee.com/@rawze:d/isx-injector...e-cm2250:e

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If it will not pass a fuel leak test (done exactly like the video shows), then that is the place to start with it. Maybe the pressure relief valve at the end of the fuel rail (most common).. or a leaky injector. If it is an injector, then a cummins injector block-off kit needs to be used to isolate and find it.

Tags:

2250 leak test, 2350 leak test, injector test, injector leak test, isx rail leakage test, isx injector test, 559 code

Gapvalley · 02-08-2023, **(Subject: Engine miss )**

I followed the video when rail pressure comes up I cut the key off. Pressure falls off instantly like less then 5secs. Used a block off tool on the rail capped off each injector and performed the test over with the same results. Rail pressure relief valve was replaced not long ago for this same code. Truck had all 6 injector put in 2 year ago. High pressure fuel pump makes a lot of noise when it ramping pressure not sure if this is normal or not.

SquareOne · 02-08-2023, **(Subject: Engine miss )**

(02-08-2023 )Gapvalley Wrote: ... High pressure fuel pump makes a lot of noise when it ramping pressure not sure if this is normal or not.

Has anyone looked inside that HP pump? Does the engine stumble any when going through the pressure test or is it smooth?

When a check valve in the head of my HP pump failed, aside from the small leakage out of one of the Torx style plugs at the top, it would stumble the engine while building pressure. I didn't finish the test to see how much it would bleed down since I knew the head was already compromised. The valve is a non-serviceable item, therefore the head needed replacement.

tree98 · 02-08-2023, **(Subject: Engine miss )**

Pressure falls how much in 5 seconds? Huge pressure drop points toward a problem with the pump. Have you taken the head off the pump yet to inspect for damage?

Rawze · 02-09-2023, **(Subject: Engine miss )**

(02-08-2023 )Gapvalley Wrote: I followed the video when rail pressure comes up I cut the key off. Pressure falls off instantly like less then 5secs. Used a block off tool on the rail capped off each injector and performed the test over with the same results. Rail pressure relief valve was replaced not long ago for this same code. Truck had all 6 injector put in 2 year ago. High pressure fuel pump makes a lot of noise when it ramping pressure not sure if this is normal or not.

It will not fall off like you describe unless something is very wrong.

You can cap off up to 3 injectors at a time. .. and of course, the issue could be with the pump itself too.

Those fuel pumps need all their guts (tappets, rollers, plungers, etc. ) replaced every 8,000 hours or 400,000 miles. If not then they have the potential to destroy the entire engine, turning it into a boat anchor with no possibility of recovery.

also, if it is leaking that badly, and you suspect more than one injector (does happen), then a poppet tester might be needed to find it too ...
ref: http://rawze.com/forums/showthread.php?t...56#pid2556

Also.. garbage, half-baked delete programming can cause injectors, relief valve, or even the pump to fail like that too. Something else to consider if it is deleted and you have not had the program reviewed by me to ensure its correctness.