2nd Gen Non-Engine/Transmission fuel gage acting up, help!

[SSolderitch]

truck has a fass 95 lp. Gauge fuel line is on the vp44 bolt.



gauge niormaly shows 17 psi - 15 running & 12-13 wot

over the past year droped 2 psi so I see 15 idle & 13 running.



changed vp44 - gauge worked the same as before the change.

Then I did a filter change & pre screen filter change - lost 1 psi at gauge?



I would see the gauge bounce with the 1 second lp pre-start



I topped off antifreeze to gauge line - gauge would sit at zero for 15 seconds then move slowly to 15 psi - takes another min.



I thought a pinched tube so I releaved the A-pilar behind the gauge and refiled the tube leaving no air. No bends or pinch points.



broke loose the fuel line and the big screw on the isolator to vent any traped air on the fuel side.



still no pre-bounce & 15 sec at zero & a slow min to get to 15 psi.



Trucks runs great but I don't like the motor started and the gauge sitting at zero..... Do I have a gauge, filter or lift pump problem?????????????



never had this before, What am I missing?

 

[sheamc]

I have had some of the same problems and it keeps going back to the fuel presssure gauge. Check to make sure no air is getting in or fuel out of any fittings, could cause the problems. I am simply going to get an electrical fuel pressure gauge and do that. I have tried everything on mine with the isolator, line full with no air, etc, etc. This will hopefully alleviate my issues. On the FASS, isn't there a port to add a fuel pressure gauge, try to borrow one and try there also, just in case. Hope it works out for you.



Shea

 

[LowFly]

There is a port on the FASS system to port your gauge to. If you have the 95 Series LP it is located on the backside of the 90 degree brass elbow that feeds PSI to the engine. It is usually marked with the letter "G".

If you have the 150 Series pump you will find this port on the back side of either the red or silver cube on the top of the filter base.

 

[SSolderitch]

I have the unit mounted on the frame back at the tank. I just have the pump, no filters.



I also have a fitting between the gauge and the tube connection- to stop gauge fluctations? Small hole - blocked with dirt?

 

[LowFly]

I have the unit mounted on the frame back at the tank. I just have the pump, no filters.

This is our HPFP Series and there is a port located on the pump itself. It is a small brass plug marked with the letter "G" or "P". Remove the plug and port your gauge

I also have a fitting between the gauge and the tube connection- to stop gauge fluctations? Small hole - blocked with dirt?

This is known as a snubber and i would recommend you remove it and run a straight line from the port connection and the gauge itself. This snubber can cause fluctuations in PSI readings.