1st Generation Dodge Cummins 89-93 Discussion of 12 Valve 5.9 Liter Dodge Cummins Diesels with Rotary Injection Pumps

Fuel Pressure Question

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  #1  
Old 03-16-2008 | 06:07 PM
RSWORDS's Avatar
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BOMBARDIER

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Got my guage installed to day and I hooked it into the banjo bolt at the top of the fuel filter. I have 6psi... 6 at idle... 6 at 60 mph.... 6 at WOT.

WTF!!!!

Any ideas? I know it is a tad low but you would think it would move a LITTLE!!!
 
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Old 03-16-2008 | 06:33 PM
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my bad.... this is on the 12valve..... um is the gauge electric or mechanical?
 
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Old 03-16-2008 | 06:39 PM
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Originally Posted by Benjamin
my bad.... this is on the 12valve..... um is the gauge electric or mechanical?
Mechanical...
 
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Old 03-21-2008 | 01:09 AM
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Originally Posted by RSWORDS
Got my guage installed to day and I hooked it into the banjo bolt at the top of the fuel filter. I have 6psi... 6 at idle... 6 at 60 mph.... 6 at WOT.

WTF!!!!

Any ideas? I know it is a tad low but you would think it would move a LITTLE!!!
That little lift pump doesn't put out much PSI. That sounds about right to me.

I may be wrong on this as I'm no VE expert... but I believe the IP has a return line for excess fuel. In other words what your IP doesn't use of that 6psi at idle just gets recycled, and the more fuel the IP uses (WOT), the less it recycles. Don't quote me on that... Hopefully some one else who knows more about the fuel system will give us a heads up.

Chris
 
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Old 03-21-2008 | 09:11 AM
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DR.org says the fuel pressure should be:

Fuel Pressure: 18-24psi at idle, 28-36 at 2000 rpm with no load.
91 Ram engine specs
 
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Old 03-23-2008 | 02:35 AM
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Originally Posted by Johnny Cetane
DR.org says the fuel pressure should be:



91 Ram engine specs
Before or after the injection pump?
 
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Old 03-23-2008 | 02:46 AM
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Bobby did you fill the line up with fuel before you connected it to the gauge ?
 
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Old 03-23-2008 | 02:50 AM
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Originally Posted by nooblet
Before or after the injection pump?

should be before
 
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Old 03-26-2008 | 04:42 PM
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I don't know where they're measuring that on Genos, but thats way way to high for where your gauge is Bobby. Pressures like that will blow the front seal out. Factory service manual says 3-5, and that should be across the rpm range with everything stock. Right now your truck isn't using enough fuel for the stock lift pump and return line can't keep it regulated.
 
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Old 03-28-2008 | 06:18 AM
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Originally Posted by DieselMinded
Bobby did you fill the line up with fuel before you connected it to the gauge ?
Yep... hooked everything up... Started the truck and the cracked the line at the gauge to bleed all th eair out.
 


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