autometer fuel pressure gauge help

[MarylandDmax]

so i just installed a 0-15 psi fuel pressure gauge to monitor the pressure coming from my fass. worked good when i finished the install and tested it before calling it a night. but when went to leave in the morning the gauge started boucing between 6 & 9 psi. im trying to figure out if this is a problem with my fass or the gauge.

- some other points:
1. the sending unit for the gauge is mouted on the fuel filter delete on the engine.
2. the truck does lope a little at idle, im aware that lb7's can do this as a result, and are sensitive to, the increase fuel pressure coming from the fass. this is the reason for me getting the gauge

Lastly, if anyone would mind sharing how they wired in their gauge, that would much appreciated.

 

[2004LB7]

does it bounce with a steady RPM/Throttle? or only at idle?

 

[MarylandDmax]

at all rpm's. when it did seem to function normally, it would hover between 8.4-8.6 psi, then drop to ~6 when on the pedel

 

[TheBac]

Moved to Gauges section.

 

[Noreaster]

Did you just delete the filter on the factory assembly & have sending unit in the bleeder hole?

 

[DangerousDuramax]

What was your fuel level in the tank? Are you using a draw straw? Low fuel level (below 1/4) while using a draw straw will cause this no matter whether a FASS, Airdog, FuelLab, etc. Install a sump on your tank and it will eliminate the problem. And, as Noreaster has asked, you installed a sending unit in the factory bleeder hole? If so that isn't going to work. Personally I install my sending units right off the pump manifold because I want to know that my pump is putting out exactly what I set it to. Mounting it there also gives an instantaneous and accurate measurement of pressure drop at the source and not down the line like at the engine.

 

[MarylandDmax]

yeah, i gueel i will extend the wires and mount it directly on teh fass pump, and i had more than 1/2 a tank during this condition. apparently finding a proper engine ground is really stressed by Autometer, so im going to do that as well.
thanks for the help!