Dracula

I have a FASS and an Isspro mechanical fuel pressure gauge on my steering column. Normally the FASS pumps a steady 15 psi, but sometimes (more than not lately) I'm getting a lot of chatter. The needle is fluctuating 5 or so psi, but more irritating is the rattling noise. I just came off of a 2600 mile vacation pulling my trailer and the chattering noise liked to drove me crazy.

I seem to remember someone telling me, or reading something on here about installing a "snubber" in the line to eliminate the chatter at the gauge. I have checked a couple of shops and an on-line store and no one seems to know anything about a "snubber". Does anyone have any recommendations on something I can install to stop the chatter at the gauge?

Thanks!

RowJ

Get a needle valve and mount it inline to the gauge. Then reduce the flow to the gauge to almost nothing. Also works well as a shut off...if ever needed.
If you don't do something right away...you can kill the gauge.
Just too much steady pressure for the closed system on your gauge!

Mine chattered for 4 months. Needle valve saved having to replace it and gauge has lasted 4 more yrs.

RJ

hamilton71801

I have a needle valve on my fuel line to the gauge that I barely crack open and it relieves most of the chatter but I know I'm going to have to install a snubber. Google McMaster-Carr...that's where I got mine for my boost gauge.

Dracula

Thanks guys! I'll look for a needle valve.

John_P

Dracula:

I had the same problem as you on my 1996 Dodge CTD 12 valve. As the Members said, installing a needle valve will stop that "chatter." FWIW, "Auto Meter" also makes a "snubber" to stop it too.

The part number for theirs is Auto Meter #3279. RJ is right about
that "chatter" killing the gauge. I had used the "DiPricol Mechanical FP Gauge" with the Isolator and anti-freeze before going full mechanical and I "killed" three (3) of those Isolators before I figured out what was going on.

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John_P

Dracula

Ouch!! I opted not to go with the isolator because of price and install headaches. I wouldn't want to kill too many of them!!! I keep a plug and wrenches in the truck in case of a leak at the gauge. I figure I can get pulled over and cap it off at the IP before I get too much diesel dripping down my leg!

Thanks for the info.

John_P

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Dracula:

You are very welcome Sir! One thing in your favor though over my 96' Dodge CTD 12 valve, is that you are probably not running as much fuel pressure as I am with your trucks. I have about 40-45lbs at the inlet to the P-7100 fuel pump and those P-Pumps have alot of internal "vibrations" etc. over the pumps in the 24 valve trucks or the CR CP-3's. Just a thought........

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John_P

infidel

Sort of surprising but with a needle valve cracked open only enough to work the gauge the full flow of fuel with the gauge disconnected is nothing more than a slow drip.

Dracula

COOL! Maybe it won't be enough diesel to run Mamma out of the cab!

stuckey200224

will the valve stop the guage from dancing. id be nice to get a steady reading on the guage

RowJ

Yes it will! Dancing is Stage 1. When dancing gets bad enough it will start 'talking' to you.
Actually slapping the stops, I believe; hence the chatter. All caused by too much pressure to a sensitive instrument and a close ended system.
As mentioned above, the smallest opening in the needle valve is all it takes to read accurate pressure.

RJ

stuckey200224

i was talking about a boost guage. will it still work and it delay the guage reading?

infidel

A gauge is a gauge. Just a needle valve should stop the pulsations.

John_P

stuckey:

Infidel is right,....the needle valve will work on any type gauge.

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John_P

oktf1black

Hey Guys, I looked on McMaster-Carr, at the snubbers. To order, I must specify the orifice size. The options are 0.004, 0.008, and 0.015. Which is the best, or does it matter?