New fuel pressure gauge bouncing???
 

Well I got a Isspro EV2 electronic fuel press gauge from genos. I forgot to order their banjo bolt so i drilled and tapped the one I had which was a bad idea! [nonono]I recommend just to buy the bolt from genos. I broke a tap tryin to tap it and then barely got it out and I drilled the little holes in the banjo bolt a hair bigger. Luckily it didn't break but I was pretty paranoid.

But anyways I got it all installed and wired the gauge up and ran my ignition, lights and ground from my tach which sits right next to it. It turns on, the lights work and everything and the needle comes up on the fuel press gauge but it comes up to about 4 to 6 psi and bounces back and forth. sometimes it'll go to 8 and sometimes to 2 psi. And its not accurate cuz higher rpms or driving doesn't affect it at all, it just bounces back and forth. I thought it was the ground and tried puttin the ground in a different spot but it did the same. Do I have a bad gauge or pressure sensor? or whats goin on? Has anyone had this problem?

Thats normal for the needle to bounce if you have a stock lift pump. I've got the same gauge as you and when I still had the stock pump it did the same thing.

yup... normal. I put in my electric LP and she smoothed out nicely!

Or put a "snubber" inline. A small valve (cracked open) followed by a rubber line (like from a grease hose) into the sensor will solve the bouncing.

what about if you have a mechanical gauge that the bouncing changes each time you start the truck. sometimes its steads at 20 psi, sometimes steady at 17 and sometimes it bounces from 15-21 or so. its weird lol. is that air in the line or something?

Bouncing is normal for a reciprocation pump. However, if it's steady at a certain spot somedays, and bouncing others, I would say you have a sticky mechanical gauge, or if you have a pressure regulator it might be acting up.... or sucking air I s'pose, but I'm willing to bet the gauge if you've done the obvious diagnostics such as checking at full tank vs low tanks, lookin for leaks, etc.

I have a electric LP and a mechanical gauge. I turned on the pump and let diesel shoot out of it rid it of any air. I held it straight up. Its steady and solid.

Honestly i assumed it was air or just the place the piston/cam lobe was when the truck started. ill have to start paying more attention because i wasnt too worried lol

ill have to try that... i just bled it from the pump end of the line, not the gauge side (because i had just fixed a drip from the gauge side)

Actually air in the gauge line helps settle down the bouncing.

I was wondering if it was supposed to be like that but wasn't sure. It just seems odd. I got a 2nd gen lp waitin to go in, hopefully that'll help it out. It just doesn't seem very accurate though cuz It bounces from like 4 psi to 8 psi and it always seems to bounce between about the same pressures even when i'm driving or just idling. Sometimes it would bounce down to 2 a few times...
Whats this snubber thing your talkin about? I may want to do this so I can an actual accurate reading.

i wondered how it changed the gauge. thats interesting. maybe ill leave my line alone for now.

I made my own snubber for mine. I took a piece of aluminum about 1" square and drilled and tapped two ends to 1/4" pipe, the two ends were not connected. Then I drilled a tiny (and I mean tiny) to connect the two threaded holes. Works on my Peterbilt too.

I just put an EV2 electric FP in today. Got the banjo from Geno's and replaced my bleeder banjo with it. Put the sensor in it and fired it up. I have the low pressure LP from Cummins so I should be pushin 15 or so at idle. The gauge bounces from 10 to 20 at idle (I guess that means I'm at 15). I punch it going down the street and it goes to 20.....after I roll to an idle it settles at 10. I'm bummed. Somebody slide me a clue. Put air in my line? I have no clue what the snubber deal is. Is it sold online? The gauge in the pillar pod sure looks cool. Be cooler if it worked.

The FP gauge I got from autometer has one I think. At least it has a paper that talks about it.

A snubber just restricts the flow so that you still get the pressure with out the spikes in pressure from the action of the piston in the pump.

Some guys even plumb a ball valve in line and close it almost all the way and this works too.

I haven't seen anything over about 9psi with my stock lp, and it'll get down to 1 or 2 psi sometimes. I need to get this 2nd gen pump in. Will a 2nd gen lp and a regulator keep the gauge from bouncing since it'll have a regulator???

This EV2 gauge does look cool at night though, the green lighting, and red needle look awesome and its very clear. I need to put some green bulbs in the rest of my yellow light gauges to match it. I think i may get an EV2 trans temp gauge too. I like them.