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Discussion Starter #1
I put my gauges in a year or two ago and installed my fuel pressure gauge with the isolator and didn't have any problems out of it till about a month ago. The needle in the fuel pressure gauge shakes really bad back and forth and makes a bunch of noise. It still show good pressure, but it doesn't move smoothly, it is always rattling. It also changes as you push on the skinny pedal. It doesn't hurt anything, it is just loud and annoying. Could it be that my isolator is just worn out? Any suggestions? Thanks...
 

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Mine did the same thing and I found a small leak on the cab side of the isolator. I took it off and topped off the coolant in the isolator and tightened it up and not a problem since.
 

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Rescue Tower
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The general consensus is to use a needle valve instead of the isolators. It's a permanent fix that doesn’t fail
 

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The general consensus is to use a needle valve instead of the isolators. It's a permanent fix that doesn’t fail
Isolators are a PITA at times... :banghead:

5 years of needle valve and no problems...:thumbsup:
 

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what does the needle valve do? i have my gauge hooked in direct with no problems....
 

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Rescue Tower
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what does the needle valve do? i have my gauge hooked in direct with no problems....
Your gauge will work fine for a while. But over time the pulses from the IP will beat the crap out of your gauge and kill it. The needle valve works similar to an isolator except you can make the orifice much smaller (they are manually adjusted), which attenuates the pulses much better.
 

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Your gauge will work fine for a while. But over time the pulses from the IP will beat the crap out of your gauge and kill it. The needle valve works similar to an isolator except you can make the orifice much smaller (they are manually adjusted), which attenuates the pulses much better.
Correct...

There is also the other problem that does happen is the diaphram in a isolator will fail and allow diesel fuel to the back of the gauge without warning.

The needle valve is a nice addition to any system like Shainer said you can fine tune the fuel pressure so it not beating the gauge to death and if there is ever a plumbing issure you can always SHUT the valve completely allowing you to travel still to repair it.
 

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maybe a stupid question. but where do i get a needle valve for a 1/8th" hose. and if i close the orfice down will the pressure take longer to change the reading on the gauge?
 

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It got a nice smooth and steady rise and fall to the gauge. Now if mine is open too far it will cause the gauge to buzz (pulses beating the gauges gears). Also there is a very rapid rise and fall jerky.

As for getting the needle valve its $8 bucks at NAPA it a Weatherhead fitting PN# WH6820
 

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so your saying not use the isolater at all? just put the needle value in its place?
 

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Correct...

http://mopar.cumminsforum.com/personal/2002/bombs/gauges/fuel-pressure-install.jpg http://mopar.cumminsforum.com/personal/2002/bombs/gauges/low-pressure-sender-install.jpg http://mopar.cumminsforum.com/personal/2002/bombs/gauges/fuel-pressure-parts.jpg
 

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thanks. i found this on ur website moperman. .good site for people to look at. good job!
 

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Cummins CrAzY
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Can you get an AN needel valve? The rest of my plumbing for my gauge is all in braided hose and AN fittings.
 

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Sorry I don't have any information on AN fittings... :confused013:
 

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Discussion Starter #15
Thanks for all the responses guys. Do you think a new isolator will fix it for a while? I guess it just wore out. I don't really want fuel running into the cab, but I will check out the valve.
 

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Rescue Tower
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Hard to say. Even if you have to replace the gauge you will need the valve so you should get it anyway.
 

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Thanks for all the responses guys. Do you think a new isolator will fix it for a while? I guess it just wore out. I don't really want fuel running into the cab, but I will check out the valve.
Common problem for isolators... The fail by either lossing there coolant or by allowing the fuel to the gauge either way they fail...:confused013:
 
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