12 Valve 2nd Gen Dodge Cummins 94-98 Discussion of 12 Valve 5.9 Liter Dodge Cummins Diesels with P7100 Injection Pumps

fp issues

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Old 04-04-2011, 06:52 PM
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Default fp issues

So, I just got my fp guage hooked up; running a sunpro 100 psi oil pressure guage I got at autozone. I had the banjo bolt tapped, and ran it through a needle valve, then to the guage. I have clear tubing from the needle valve to the guage, so I can tell I have fuel. (Btw, the banjo bolt I tapped is the one on the side of the pump, on the drivers side...towards the firewall). I made 4 or 5 test runs with the needle valve adjusted several different ways, and this is what I saw. I even opened it up all the way, so that the needle was pulsing, just to make sure I was actually getting fuel. No matter what I did, how hard I ran it, I didn't move much from around 11-15 psi....it almost seems like a vp44 fuel pressure.

Is this indicative of a ofv going out, or a worn out lift pump? And what would I test from here to try and narrow it down, before I start throwing parts at it?
 
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Old 04-05-2011, 01:56 PM
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Could be either. Start by pinching the return line off the overflow valve and see if your fuel pressure comes up. If it does, your ofv is bad.
 
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Old 04-05-2011, 03:45 PM
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Yep,, just did that today at lunch, and fp jumped to 60, so I've got a new tork tek 020 ofv on order as we speak. It made more sense to pay 20 bucks more for an aftermarket one than buy another stock one. Hopefully, with this fixed, ill actually see a gain in mileage and performance. (Albeit not at the same time, for a while, )
 

Last edited by dennhop; 04-05-2011 at 03:46 PM. Reason: stupid tiny phone keyboard
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Old 04-05-2011, 05:32 PM
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Good deal.
 
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Old 04-05-2011, 08:54 PM
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tork tek doesnt mess around, good decision
 
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Old 04-05-2011, 10:03 PM
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ordering one tmo
 
  #7  
Old 04-08-2011, 12:08 AM
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Well, it came in in the mail today, so I quick slapped it in, and it made a huge difference. Its night and day as to how the truck acts and responds. Fp is around 25 psi right now, and I intend to bump it up a bit more, throttle response feels much more responsive, and the truck feels a lot quicker overall. I have a feeling I won't get a good mpg estimate for this month though,
 
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