2nd Gen Non-Engine/Transmission Fuel Pressure Gauge

[Richterno1]

I have a mechanical Fuel Pressure Gauge installed with an isolator, its an autometer ultralite. the issue is that the needle bounces around a lot. i have a fass and at idle I'm at about 14psi but it bounces up and down a least half a psi. is this normal? its done this since new and with new fuel filters. the only time it seems to stabilize is when i get on the throttle around 20 psi boost.



please help.

 

[SRath]

I think some of the guys have used a small needle valve, barely open and in between your line and the hole you screw it into, to restrict the pulses that are probably causing the needle to bounce.



We always used to put several spiral coils in our copper oil pressure gauge lines to prevent needle bounce on our Camaros and such. Just normal engine vibration and car bouncing could do that. You will notice that most brake hard lines have coils in them when they exit the master cylinder for the same reason, though in that case it prevents pulsing brakes.

 

[Hammer]

With a FASS pump you should have no needle bounce,or pulse,at all and it should remain a constant pressure. It sounds like air in the isolator line and not a FASS issue. Where are you taking the pressure at for your FASS?... ... . Andy

 

[Richterno1]

With a FASS pump you should have no needle bounce,or pulse,at all and it should remain a constant pressure. It sounds like air in the isolator line and not a FASS issue. Where are you taking the pressure at for your FASS?... ... . Andy

the reading is coming from a tee on the supply line about 18" before the vp44. then goes through about 20" of hose to the isolator and then another 3+/- of hose to the gauge on my pillar.

 

[Big Rich 01]

i have the same guage ond i ran about 4 feet of line to the isolator coiling the excess to get rid of the pulse.

 

[MHoverson]

I have the same setup on mine but I have an Isopro gauge. I've never seen any bounce with mine. I did have to bleed the isolator after I installed the FASS HPFP though, the pressure reading was off. After that all was well.

Did you fill the gauge side of the isolator with anti-freeze?

 

[RolandJ]

i had to add a snubber in mine. it takes up the surge and vibration that a diesel makes its like a 5 dollar part i dunno why they cant just give it to you. i called auto meter and they gave me the place to get it. .

 

[Hammer]

In the thread below I show where and how I take the pressure from my FASS. Enterprise Engine takes the pressure reading right at the pump and runs another line forward and then uses a mount to use a electric gauge which is then mounted in the truck. If you look at the photos you will see the place in the FASS where the pressure is taken and the sender mounted on my firewall. My pressure does not bounce,fluctuate of move excessively at all. Flip the switch,turn the pump on and its at 45 psi and stays there and never moves off of it. Again,if your gauge is "bouncing" then its a problem with the sender or isolator because the FASS does not fluctuate like that... ... ... . Andy



https://www.turbodieselregister.com...discussions/187499-gauge-mount-selection.html