Hello;

I installed a mechanical fuel pressure gauge (ISSPRO) on my truck several years ago. it worked fine for a long time. The about a year ago it started making a lot of noise.

When it is noisy, the needle is fluctuating like crazy! The overall pressure readings are where I want/expect them to be, but it bounces around.

So, I thought I had a bad gauge until I changed my fuel filter. Every time I change my fuel filter the gauge is perfectly smooth and quiet.

I have the stock filter-housing, using Fleetguard filters. I have changed the lift pump to an Airtex and re-located it with the kit from Geno's. I also place an in-line filter from NAPA between the lift pump and the tank.

I have the gauge connected with an isolator (using anti-freeze); and then the isolator connects to one of the ports on top of the filter housing. This is the same connections that it has been since day one.

Since it gets smooth after a filter change, but noisy again after a few hundred miles; it makes me think that I have dirt in my fuel tank..

Any other thoughts/suggestions?

--Matt

 

I have the same problem a metal mechanical gauge with a copper line to the gauge first the line and gauge are like a banjo resonating sound from the injector check valves people think I have a hole in my firewall Napa sells a 1/8 needle valve that can be installed at the fuel filter going to your gauge turn it down to controlled the flutter I didn't do it yet I hear if I use some 1/8 or 3/16 air line made for trucks that will quiet my noise

 

It sounds like when you installed the fuel pressure gauge setup that you didnt use a snubbing device. That being a dedicated snubber or a needle valve. Having a snubber in the fuel pressure gauge line is essential because the hydrodynamic fluid pulses coming from the VP transmit down through the fuel supply line and will beat up any mechanical gauge or electric gauge sender. Depending on how the fuel pressure gauge line setup is configured sometimes using two snubbers is better.

The reason why your gauge acts up when the fuel filter gets dirty is probably because the filter is causing the pulses to increase in magnitude felt by the gauge simply because they cant pass through the filter as easily and the gauge line is plumbed after the filter. This would potentially become an aggravated situation too when still using the stock fuel lines too given their smaller diameter and less flexible metal.

You'll want to pick up a snubber soon otherwise you'll destroy your ISSPRO gauge. Snubbers like this Dodge Cummins 5.9L RLT Fuel Pressure Snubber-Geno's Garage can be found at Geno's or you can pick up a needle valve at the hardware store. I personally dont care for the needle valve simply because ya never know if its set too loose or too tight.

 

This happens to my gauge as well (also an ISSPRO), and I have a needle valve. I don't like the needle valve approach, since mine never seals even when closed.

Every now and then my gauge will rattle like yours did when the line fills up with fuel. All I do is disconnect the gauge line in the can and put that in a catch bottle of some sort. Then I disconnect the engine side and blow out the gauge line. Once it's clear I hook it back up and it's good to good again.

 

jrs_dodge_diesel, it sounds like you need a better snubber. Fuel pressure gauges are designed to work with the fuel up to and in the gauge so for you to have to create an air cushion tells me that those pulses are too intense without that air in the line.

 

I have an ISSPRO electric gauge with snubber and it dances a bit over about 2 psi.

If you think it is dirt in the fuel tank you should probably drop the tank and check the seal for the fuel gauge sender etc. or instal a filter at the tank outlet and see what you get after a while by cutting it open.

I was actually very surprised how clean my tank was after reading a lot of posts about dirty tanks.....

 

SIX, if your gauge "dances" constantly then thats a problem and will eventually degrade the mechanics of the gauge causing it to read inaccurately. ISSPRO knows about the 2ng gen truck pulse issue too and will even void a gauge warranty for that reason.

But if the gauge occasionally bounces down a couple psi while driving then that could be merely a fuel pressure regulator maintaining pressure.

 

I have an older Dipricol fuel gauge . I think 5-7 years now. I have a fuel Isolator and a needle valve. my gauge has made noise for about 4 years.
this last fuel filter change since I have a fass 150 pump without filters I used a 3rd gen stock fuel filter. 7 micron. funny thing now is the gauge is not making noise. I have the needle valve in front of the isolator.
I dont know if moving the needle valve further away from the isolator would help. Also some of the buzzing sound I heard I found was due to the actual gauge making some sound against the gauge holder. I popped the gauge out and wrapped a single wrap of black electrical tape on it as a cushion.
my gauge when it was buzzing never showed a jumpy needle.

 

Even with a snubber, mine goes crazy (vibrates)for a while after I change out the filter. I'm guessing it's the last bit of air in the line.

 

My gauge does the same thing after a new fuel filter the gauge bounces around and when I bump the fuel pump a few times to get the air out turn the key to off the gauge shows pressure and goes down very slowly that's when I loosen the fuel line at the gauge with a drip can and air bubbles come out tighten the line bump the fuel pump and loosen the line again tighten the line and start the engine the gauge is usually steady the more the air in the line the more the bounce I have some kind of a snubber in front of the gauge his inside looks like an old fuel the Chevy's used that and were at' the fuel entry to the carb

 

Thank you all for the response!! My apologies it took me so long to get back on here.

Sounds like many others have had this problem. This is the first I have heard of a "snubber" for my gauge setup. I will look into those. Thanks for the tip.

My situation is different than what some of you describe. My gauge becomes perfectly smooth and quiet immediately after a filter change.

Still,,,, it seems weird that I would run this for years and never have a peep out of the gauge.

I forgot to mention,,,, about 2-3 months before this all started I think I may have got some bad fuel. I was hauling a load about 8 hours from home and filled up at a truck stop. After driving about 15 minutes from that fill up, my water-in-fuel light came on. I purged at the filter canister by opening the valve and letting the pump run a bit and added some fuel additive. The light came on a couple more times and then quit. I changed the filter when I got home and didn't think any more about it.

Thanks again for the help.

 

I forgot to mention in my last post a clarification. Katoom, when I said I relocated the lift pump to the frame with the Genos kit, that included the "big line" kit that replaced the stock supply lines with larger flexible hoses.

Thanks again to all for the help!

Matt