Fuel pressure question

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Aug 19, 2017 | 02:49 PM

RhinoRidener7

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Fuel pressure question

I just put a set of full force diesel stage 1.5 on stock fuel pump and put a brand new fuel pump in a few months back and my gauge was reading about 20psi to 40psi based on how I was driving after install and today I was just cruising at 55 at about 2000rpm and the gauge was reading 60 psi I would get in it and it would drop to 40 or 45 I put the injectors in about 2 weeks ago and it wasn't reading this high until today I was just curious if this is a normal psi? There arnt any fuel leaks I can see.. I've been running the truck on a 65hp tune from hydra and I installed the hydra a few days ago so I don't know if the tuner is making a difference any help would be appreciated

1995 7.3l
Mods:
Stage 1.5 full force
hydra tuner- high idle, stock, 65hp, 80hp, 25hp how tune, 40hp tow tune
Diamond Eye 3inch-5inch straight pipe
Wicked Wheel II
Glow shift gauges- Fuel Pressure, Boost, Pyro

Aug 19, 2017 | 04:09 PM

Fuzzynuts

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You want around 65 psi at idle and it's good if you can maintain that at open throttle. Some drop is pretty normal. Damage can occur at less than 40 psi.

Aug 20, 2017 | 12:20 PM

B-Rad88

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Joined: Dec 2016

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From: Southwest Missouri

What fuzzy said. Anything below 40 could mean a problem. I am running stage 1's with 6 cusotm DP tunes, and I drive on my 60HP daily setting, and when i go half throttle, i can get it to about 42 PSI. If i punch it, I dip slightly below 40. So i try to avoid doing that for longer than a few seconds. I don't even use my 5th or 6th setting because I don't have the fuel pressure when I get on it. E Fuel is really the only way to go with this setup.

Aug 20, 2017 | 08:42 PM

97-psd

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Joined: Mar 2007

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From: knoxville, tn

I believe 20 psi is the lower limit you want to avoid as it is the damage threshhold. Bone Stock, these things will run 40-45psi. They run better at ~60, which is why people either shim or buy a new Spring for the fuel pressure regulator. E fuel is best because it will deliver the higher pressure at higher volume. If you saw it drop to 35 while under WOT then I would definitely back off some. Injectors, as you know, are pricey.

Aug 20, 2017 | 10:08 PM

RhinoRidener7

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Quote:

Originally Posted by 97-psd

I did the bb shim and now I'm setting at about 92psi at idle, I haven't taken it down the road yet, is this way to high at this point?

Aug 20, 2017 | 10:14 PM

z31freakify

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From: Las Cruces New Mexico

Yes it is Max should be 75 psi

Aug 21, 2017 | 10:02 AM

97-psd

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From: knoxville, tn

Quote:

Originally Posted by z31freakify

Yes it is Max should be 75 psi

Agreed, 92 is too high

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Aug 24, 2017 | 02:08 PM

Hussler

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From: Medford Oregon

Quote:

Originally Posted by RhinoRidener7

I did the bb shim and now I'm setting at about 92psi at idle, I haven't taken it down the road yet, is this way to high at this point?

When measuring fuel pressure take the average, not the peak if using a mechanical gauge. You did not mention what type of gauge you are using, mechanical, liquid filled mechanical or electronic.

Aug 24, 2017 | 02:10 PM

#10

RhinoRidener7

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Quote:

Originally Posted by Hussler

When measuring fuel pressure take the average, not the peak if using a mechanical gauge. You did not mention what type of gauge you are using, mechanical, liquid filled mechanical or electronic.

mechanical from Glow shift

Aug 25, 2017 | 02:44 PM

#11

DZL JIM

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From: North East Ohio

Do yourself a favor and stay away from Glowshift.

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Aug 25, 2017 | 03:29 PM

#12

Jarrett Campbell

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Joined: Jul 2015

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From: Aransas Pass, Tx

Quote:

Originally Posted by DZL JIM

Do yourself a favor and stay away from Glowshift.

As a current glowshift user, this comment worries me. Are they just inaccurate or is it a longevity issue?

Aug 26, 2017 | 02:14 PM

#13

Hussler

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Joined: Sep 2007

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From: Medford Oregon

Quote:

Originally Posted by RhinoRidener7

60 PSI at cruising is pretty good. Some drop is expected when getting on it with the mechanical pump, that's why some go with e-fuel.. The piston in the pump is very small, see picture below of a disassembled pump.

Could be you just had air in the fuel after replacing replacing injectors causing lower pressure, just a guess.

Aug 26, 2017 | 02:25 PM

#14

Hussler

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From: Medford Oregon

Quote:

Originally Posted by RhinoRidener7

Well I will just have ease around in stock mode(since that gets me the best fuel pressure) until I can get the e-fuel kit from strickly

I put Strickly Diesel on my 97. After trying another vendors just bit the bullet and chocked it up to a learning experience, expensive lesson. It's top notch quality and looks like it's suppose to be there, imo.