Electronical Fuel Pressure Gauge

[MrMarty51]

I installed two sending units from GloShift for their 0 to 30 PSI gauge.
One sending unit at the AirDog lift pump and the other hooked into a swivel JIC adapter fitting at the injection pump.
I have never been able to get a good reading from either of the sending units, thought it was a bad unit so ordered another SU and installed it with the same results.
Once in a while there would be a fairly accurate reading from the gauge, I think but never real sure.
Yesterday, thought, going to get to the bottom of this.
Having the little mechanical gauge from when I was running the other style pumps, teeed into the hose between the FFM and the IP, hooked in that little gauge with surprising results.
The initial pressure buried the gauge. Not sure how deep.
Backed off the FP regulator screw about a 1/4 of a turn and brought the pressure down to about ten, according to the bouncing needle.
Twisted the adjustment back up about 1/8th of a turn and took the average.

And so, with the pressure spiking and dropping so fast I believe that the GloShift sending units are actually creating electronic spikes and causing the gauge to read at maximum pressure, 30 PSI.
I’m not sure if there is a gauge sending unit that could, or would eliminate the spiking from the gear-rotor pump.
Anyone have any advice ?

 

[MrMarty51]

All that pressure spikes and valleys must have wiped out the sending units, or the gauge.
Turned the ign switch to run for the WTS lamp and the gauge pegged 30, front and rear sending units.
@Big T and @ak diesel driver
I think Big T might have the AirDog and AK has the raptor unit.
Do You guys have gauges hooked to Your pumps, if so what brand, and are they mechanical or sending unit electronical ?

 

[ak diesel driver]

Mines an auto meter electric

 

[MrMarty51]

Mines an auto meter electric

Okay, thats what I’ll get coming.
Are You running right at the lift pump pressure gauge port or at the injection pump, or both ?

 

[dbrannon79]

is the regulator the type that controls the pump electrically or does it just bypass to flow back to the tank? if it just bypasses the flow, then you might need a snubber or bladder to eliminate the pulsing pressure. the IP is creating the pulsing when it takes in some fuel as the injectors fire. mine does this on both trucks with the facet dura-lift pump I have on them. I can't remember if it's the snubber or a bladder that takes and smooths out the pulsation on pumps to give you a smooth flow of pressure.

you might even look into a remote mount pressure regulator similar to what's used on older hot rods when they do an LS swap. that would require a return line but might help smooth out pressures, even aid as a fail-safe so no matter what the pump does, you'll never exceed that set pressure.

 

[ak diesel driver]

At the IP

 

[Will L.]

The snubber is what smooths out the gauge. But usually the bigger pumps that run non stop have a recirculating hose and that calms the pulse.

 

[MrMarty51]

The AirDog does have a return to tank bypass regulator.
I’ll check out the pressure snubber systems and maybe try one of those in the IP sending unit before ordering more gauges.