Low fuel pressure

[Rawze]

(08-08-2026 )Jduran0114 Wrote:  I have a cummins 2250 with 1 million miles, I replaced the injectors

Why did you replace injectors?.. just for the fun of it to waste moneys?.. or was there another cause like them not passing injector leak test, etc?.

Also, did anyone bother to put the new injector trim codes into the ecm?. On those CM2250's they have to be manually types in each time you replace/install an injector via Insite.

Are they genuine OEM injectors from a stealers$it?... or something else?.

(08-08-2026 )Jduran0114 Wrote:  ... fuel pressure ... has soon I let go my command stabilizes back to 7500psi and my measured drops between 2800 to 3500psi for brief moment and goes back to 7500, my reading do jump around

When you stomp pedal and let off it suddenly, it is normal for it to have a few hundred psi dependencies.. it has stabilize again. Its a big engine. Also, the system id designed to allow for 300-bar pressure difference.. its a bypass charging type of system, so the fuel pressure will never be exactly what commanded pressure is. As long as its less than 300-bar pressure difference, its fine.
related info: https://rawze.com/forums/showthread.php?...6#pid75536

(08-08-2026 )Jduran0114 Wrote:  ... when idling in the hundreds,
...could it be that my new injectors exposed a already weak fuel pump?

THE FUEL PUMP needs its guts replaced every 400k miles or equilevent hours. Those CM2250's (all common rail ISX models in fact) are notorious for the fuel pump wearing out and then it destroys the entire engine with zero warning!. - If it has more than 400k miles on that fuel pump,.. it needs its guts replaced A.S.A.P.!!!.. and if your not sure, then it needs it done any ways just for good measure.

(08-08-2026 )Jduran0114 Wrote:  It does pass a injector leak test with insite, getting fitting to do actual leak down test but I don't lose more than 1kpsiin one minute.

Did you do the injector leak test just like this video shows?>.. at full pressure?... or at idle pressures?.. because they often will not leak at idle pressure, but will at full pressure. - Do the test exactly like this video shows...
info: https://rawze.com/forums/showthread.php?...3#pid75483

Also, power loss/changes after injector of other work is done can be many, many things. - Who knows what someone did in there?..

... valve adjustment improper?
... leaky feed-tube at high pressures?.
... NON oem or rebuild injectors?.
... incorrect part number replacements?.
... other things got disturbed?.
... bad delete programming that is not allowing for proper cylinder balancing?.
.. etc.etc.etc.

Also, Using the CT software to fully test the engine and its operating state, fuel control, etc. is the proper way to see if the engine is even trying to provide full power, etc. - For all anyone knows, the ecm itself could be telling the engine to hold back something due to some unhappiness inside it,.. and the only way to truly see this is with CT when test driving it, not Insite.

==============

Related...

Does this engine have a delete file in it?... if so, then it needs to be copied out and reviewed to ensure it is not harmful to the engine. - Last thing someone needs is a program that is eating the guts out of the engine and every few years, having to inframe it or replace injectors, or turbo's, etc.. because of some engine killing mistake in the de-mandate file. - Does not mater how well you think it runs.. ISX can eat its own guts out by simply some idiot hiding faults and then not re-programming ecm for proper engine mode changes, etc.etc.etc.. like most of those morons usually do.