Low rail pressure??

JRcummins

JRcummins

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Joined
Apr 12, 2008
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At idle rail pressure is about 1,000-3,000 psi low...and the more throttle you give it the farther behind it gets
 
i put three different ones in it and nothing changed...this is also a d-max pump i just put on
 
JRcummins said:
At idle rail pressure is about 1,000-3,000 psi low...and the more throttle you give it the farther behind it gets
Click to expand...

If your idle pressure is truly 1000 to 3000 psi low on your 2003, I'm surprised it even started. That would mean you're at 2,000-4,000 psi at idle (based on my 2003 idling at 5,000 psi in neutral). If I recall our CR's need about +/- 3,000 psi while cranking to fire.

What type of rail pressure gauge do you have? With modded and dual CP3 setups my DiPricol gauge reading starts to drop over time. I got a new harness from DiPricol that partially fixed this issue, but it is still not 100%.

How is the gauge connected? Do you have a pressure box installed? If yes, is the gauge hooked in before the pressure box?

If it's hooked after the pressure box, you're reading the fooled pressure. The pressure box manipulates the rail pressure to read lower so the ECM adds more fuel so if you go to WOT it would make sense that the pressure reading gap gets larger.
 
i used a scanner for all my rail pressure readings...at idle rail pressure set point is 5,000-5,500 but its only makin about 3,500-4,000
 
So you don't have a rail pressure box connected or programmer downloaded at all?

If you do, can you remove the box or program back to stock and retake the reading? Otherwise, the scanner is reading the output from the ECM after the rail pressure signal has gone through the pressure box or new program.

If you don't, maybe the rail pressure relief valve is shot.
 
i scanned it when it was stock and when it had the edge EZ and smarty tnt....nothing changed

the rail pressure relief valve has already been replaced...nothing changed
 
yea it cranks a little more than usual but it will start and then you can just watch the rail pressure fall down to about 3,500 at idle. i've also replaced the rail relief
 
yea the injector lines were off and i put a bigger set of connecting tubes in but everything was torqued to specs and theres no fuel leaks

im prretty sure the rail reliefs alright
 
did ur new tubes have edge filters in them and how much bigger is the bore on the new tubes dou have a bored out rail?
 
edge filters??
not sure of the bore but i know they're not real big and the rail is stock
 
an edge filter looks like something that plugs the bore of the tube it keeps fuel from pulsating also acts as a flow dampner so u dont have a surge 24v u can drill them out and make one lope like a race car i have ni done any testin on common rails as much but i have noticed a boreed out rail stock is 10mm i ran a 12mm and noticed lower pressure i have done a new one 14mm but the flow of hydraulics will tell u less pressure= more flow
 
yep i know what your talkin about...didn't know they were called edge filters...and to answer your question no they are not there anymore
 
might try puttin ur old tubes in and see what ur rail does john deere uses flow dampners on the rail i am gonna try and maybe see if one would work cause they are a lot bigger
 
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