p7100 fuel pressure - Dodge Cummins Diesel Forum

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Old 09-03-2012, 10:05 PM   #1 (permalink)
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p7100 fuel pressure

My girl friend has a 95 12V, (see my signature for mods), we are running her fuel pressure guage off of the top of the stock fuel filter. She has a raptor 150 lift pump. Once we installed the guages the fuel pressure is only reading 12psi at idle, and when you stand on the throttle it reads almost "0". My questions are 1) What is the correct Idle, and WOT fuel pressure she should be showing. 2) Can I achieve the correct pressure with turning up the fuel regulator on the raptor lift pump?

Im not to savvy with the 12 valve engines, but the motor is pretty decently built and I would think it needs a lot more pressure than that.
thanks for the help.
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Old 09-03-2012, 10:39 PM   #2 (permalink)
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The P7100 is designed for 35 PSI, some people have had better luck running 40-45 PSI. The factory lift pump usually puts out around 20-25 PSI at idle and up to 35 PSI under load, that's if the rest of the fuel supply system is up in good running order.

I'd first check to make sure the overflow valve is the correct one needed for an electric lift pump, Tork Tek sells the one needed for an electric lift pump. The fuel regulator adjustment might work if that's the problem, but this could be related to a bad overflow valve or something else in the fuel supply system.

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Old 09-03-2012, 11:04 PM   #3 (permalink)
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You might have a restricted fuel filter
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Old 09-04-2012, 12:23 PM   #4 (permalink)
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Sounds to me like Either a pump for a 24v truck or a bad over flow valve.. The over flow valve can be moddified with a pen spring.. But on my 175 pump i had i ran 60psi.. 160 and 175hp pumps are known to have a lazy cam which does allow adequate fill of the barrels. If they dont fill all the way then you lose lubrication in them which can make plungers stick or crack a barrel. Neither are an easy fix.
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Old 09-04-2012, 12:56 PM   #5 (permalink)
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Are you using a fuel pressure gauge isolator?
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