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Permanent Fuel Rail Pressure Gauge

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Here's a simple little mod that saves you time by enabling you to check your fuel pressure any time you want. The parts:
1.) A 0-60 PSI liquid-filled 1-1/2" fuel pressure gauge from Jegs, p/n 555-41012
2.) A brass 1/4" flare x 1/8" female NPT straight adapter fitting from here: https://www.amazon.com/Caspers-107133-Schrader-Pressure-Fitting/dp/B0056VAC42

107133-320-600x600_0.jpg

Use teflon tape on the gauge pipe threads then snug it on the adapter:
gC3A9fQ.jpg

After the engine has been sitting overnight and is cold, let any fuel rail pressure off first by depressing the needle. Have a rag handy in case the fuel squirts out. Then remove the core needle from the fuel rail Schrader valve w. an extractor tool, same tool used for bicycle tires.
3lK0DGH.jpg

My ever-present red-eyed helper:
dg8tzeH.jpg

Screw the assembled gauge and adapter on the Schrader valve. Since it's a flare, do not use teflon tape, and do not over-tighten:
hGQfdJc.jpg

Start 'er up and check for leaks. Hmmm, I'm about two PSI low:
s2GkMcQ.jpg

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Thanks. He usually fetches the correct tools I need w/o fail, but keeps screwing up the wrench sizes. Dayemed if I can teach him the difference between SAE and metric! :nuts:

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nice.

 

how about an electric variable pressure switch connected to a similar electric gauge...say an oil PSI gauge with an oil PSI sender adapted to fit.

 

that way you could read it in the cab...

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are you sure that you want a line carrying gas! into your cab! :eek:

 

Har - you replied before I could. :D Exactly right, if I were to run a fuel pressure gauge into the dash it would be an electronic w. the sender in the engine bay. I just wanted a quick check permanent FP gauge to look at w/o going thru the hassle of hooking up an external gauge.

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are you sure that you want a line carrying gas! into your cab! :eek:

 

Har - you replied before I could. :D Exactly right, if I were to run a fuel pressure gauge into the dash it would be an electronic w. the sender in the engine bay. I just wanted a quick check permanent FP gauge to look at w/o going thru the hassle of hooking up an external gauge.

 

so, do you think I could do this with a stock sender and stock oil pressure gauge?

 

I know they're not all that accurate, but as a temporary solution, I should think that it would work...

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You mean use the stock oil pressure sender installed on the fuel rail Schrader valve sending to the stock oil pressure gauge? Yeah, that would work with the right adapter plumbed on the Schrader valve, since the stock oil pressure gauge reads up to 100PSI (pegged). But I don't think it's really necessary to monitor FP in the cab; a wideband air/fuel meter or a tranny temp gauge would be much more useful.

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You mean use the stock oil pressure sender installed on the fuel rail Schrader valve sending to the stock oil pressure gauge? Yeah, that would work with the right adapter plumbed on the Schrader valve, since the stock oil pressure gauge reads up to 100PSI (pegged). But I don't think it's really necessary to monitor FP in the cab; a wideband air/fuel meter or a tranny temp gauge would be much more useful.

 

 

:P

 

I have two spare gauge locations with my current setup, and already have a tranny temp gauge, and OBA pressure gauge.

 

just because I don't need it, doesn't mean I don't want it

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I have two spare gauge locations with my current setup, and already have a tranny temp gauge, and OBA pressure gauge.

just because I don't need it, doesn't mean I don't want it

 

If you have room for any gauge, the A/F ratio gauge is IMHO the most useful and important of all, besides the basics of course. I look at it more than the rest; gives instantaneous results of your engine performance and well-being. :cheers:

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Thanks. He usually fetches the correct tools I need w/o fail, but keeps screwing up the wrench sizes. Dayemed if I can teach him the difference between SAE and metric! :nuts:

 

 

LOL...well, I have the solution for that:

 

Soak the metric wrenches in beef broth, and the SAE in chicken broth. Then, you can say "Get me the chicken 5/8's", or, "Get me the beef 13MM". Of course, he might run off with one occasionally... :roll:

 

Still, a beautiful dog. Used to have two myself (They're hanging out 'Upstairs' now...fetching the tools for the Master Mechanic).

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I'll have to try that. But he'll probably try to eat the wrench - this guy eats more than any dog I've ever had. :cheers:

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So to depressurize the fuel system you are just going to unscrew the gauge now that the schrader valve is gone?

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These systems don't hold any pressure to be worth worrying about...and the Renix systems don't hold it for more than a few minutes at best. ;)

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These systems don't hold any pressure to be worth worrying about...and the Renix systems don't hold it for more than a few minutes at best. ;)

 

Surprisingly when I pushed down the Schrader valve needle after sitting all night I still got a spritz of fuel. :eek: I guess my check valve in the pump is still working a bit. And yes, to depressurize the rail now I'll just crack loose the gauge, or maybe put a "T" fitting in later.

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do NOT run an oil pressure gauge for fuel, it wasnt meant for that and could be a fire hazzard.

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do NOT run an oil pressure gauge for fuel, it wasnt meant for that and could be a fire hazzard.

 

I thought about that.

 

the only potential fire hazard is that it's a single pin and grounds out through the threads.

 

I think a double pin electrical pressure gauge would work nicely...with an aftermarket gauge

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that and gas wil eventually degrade the plastic hose.

 

 

what plastic hose?

 

it would be mounted via brass or such to the fuel rail. no hose to the interior.

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What plastic hose? JeepCo is talking about using an electronic gauge, i.e. the stock oil pressure gauge to measure fuel pressure. Stewart Warner makes senders that can be used for both fuel and oil applications. But in order to use a sender like the below with the stock dash gauge, you would need to know the resistance and voltage polarity outputs of the sender to determine if it is compatible with the stock MJ dash gauge.

 

http://www.sw-performance.com/index.php?page=details&p=114875

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