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

how does getting a new ofv for the pump help? i thought it was just a banjo bolt? How do they help with fuel pressure?... JOIN NOW TO REMOVE TRACER

p7100 pump ofv?

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Old 09-17-2010, 06:34 PM
bowtech's Avatar
Diesel Bomber
wanting to be in the woods bowhunting!

Default p7100 pump ofv?

how does getting a new ofv for the pump help? i thought it was just a banjo bolt? How do they help with fuel pressure?

bowtech's Sig:94 auto 4X4 cummins with #100 plate slid,215 injectors, AFE intake, single 6 inch bull hauler stack,boost elbow ,glow shift boost and pryo gauges, suncoast valve body, billit dacco single disk tc with tc lock up switch
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Old 09-17-2010, 08:40 PM
Diesel Fan



The Overflow Valve is on the banjo fitting on the return line at the forward end of the the IP. Inside is a spring and a bearing that holds pressure in the pump. When working properly it maintains a balance between the injection system and fuel flow returning to the fuel tank. As the spring wears the flow can lose that balance. If you notice a loss of performance that is a good place to look. In a pinch the spring can be stretched to give some temporary improvement in performance , but replacing the valve is an easy and cheap fix.
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Old 09-17-2010, 08:41 PM
estrada5.9's Avatar
Diesel Fan



The Over Flow Valve is a check ball type setup and when the spring gets weak the its lowers the fuel pressure in the pump because it is letting fuel past to easy so to speak.

A simple temporary fix is to stretch the spring this will get you to a parts store

They are typically around 60 or so but probably 90 or 100 from dodge.

Should read 22 PSI at idle and 25-30 PSI at 2500 RPM

You can test the OFV by pinching off the return line. If the pressure goes up then the OFV is bad if it doesn't the LP is bad. You can pinch the return line with some vice grips on the rubber part of the line by the firewall

Symptoms of worn out OFV

Low RPM miss / instability
Hard starting
Engine dies at idle (especially when hot)
Fuel Filter cracking

estrada5.9's Sig:1997 2500 4x4 5spd 35/3b

2003 2500 4x4 6spd 62/71/14 over S472

2000 Jetta TDI 5spd
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Old 09-17-2010, 09:17 PM
Diesel Enthusiast



well if a rig has 100,000 miles or more on it should you just replace it as a maintenance thing to know your good for another 100,000?

lodal cummins's Sig:1996 Dodge 12 Valve,100 Fuel Plate ff, Silencer Ring Removed, bhaf, AFC Tuned, Boost Elbow, 4"turbo backstage 2 75hp injectors
Boost & Pyro Meter Gauges, Automatic with low stall convertNer & Shift Kit
kdp killed,timing 15.5* 3kGSK Email: lodal@comcast.net
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Old 09-17-2010, 11:13 PM
bowtech's Avatar
Diesel Bomber
wanting to be in the woods bowhunting!


So if i take that bolt out the spring is just loose and i can stretch it out and put it back in and see if thats the problem? when i says fuel filter cracking what that mean like literally it cracks? how would it do that?
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Old 09-18-2010, 07:49 AM
Diesel Fan



That helped in my case.

Best to take off the entire valve assembly and take it to a bench to take apart or you may lose the spring or bearing. Also make sure to grab the plastic bushing/ gasket under the banjo fitting.

Check Ebay- I got mine for $25.00

Last edited by ktfroy; 09-18-2010 at 07:51 AM.
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Old 09-18-2010, 09:07 AM
tiremann9669's Avatar
Diesel Bomber
Stoned in the mornin drunk in the afternoon



Only buy a Bosch don't buy aftermarket crap

tiremann9669's Sig: 96 12 valve Club Cab 4X4, K&N Intake,4'' Straight Pipe, 285/75R16 Bridgestone Revo's,on 16X8 American Racing Black steelies, Firestone ride rite airbags Future Bombs Guages, Aftermarket lift pump, Fuel plate, Injectors,etc,etc,etc Oh Yea I'm sure a clutch will come into the picture sometime too
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Old 09-18-2010, 09:45 AM
Red_Rattler's Avatar
High Tech Redneck

Jacob Boness

All aftermarket isnt bad, I have one from tork technologies and it is a high quality item and solved my ofv issues without a doubt.

Red_Rattler's Sig:JAKE


03Flame Red 2500 4x4 QuadCab Handshaker HO,Kore HP Kit, Smarty REVO, AIRDOG II 165, Banks TechniCooler, K&N FIPK, MBRP Cool Duals 6inch tips, GunSlinger Pistol Grip Shifter, SRT Inine 6 Hood, Jacobs Brake

95 2500 4X4 Ext Cab Handshaker "BUCKN' BADGER"
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Old 09-18-2010, 10:54 AM
Diesel Fan


Default p7100 pump ofv?

You guys just made my day. Was getting ready to change my pump due to what was like dead pedal, but more of a power loss and seriously eratic idle, popped the banjo bolt out of another pump laying in the shop and is purrin. Thanks.
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Old 09-18-2010, 01:56 PM
bowtech's Avatar
Diesel Bomber
wanting to be in the woods bowhunting!


when you take out your bolt you screw it out and pull it up to get it out bc it hits on the metal?
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