Hey guys,
Running an 06 F350 with Blue Spring upgrade for over a year. I have Isspro EvII Fuel Press gauge.
Its always ran at 55-60 PSI. Then on my last long trip stopped at to refuel & shortly after my press climbed up to 90PSI. Got to the hotel & changed filters still 90PSI.
No running issues with the truck, no lack of power, no smoke.
Got back home & dropped by the local diesel mech, he put on a mech gauge & his read 30PSI??? Didnt trust his gauge so bought my own & it reads 50PSI.
I ordered a new blue spring & will see where that puts my press & I ordered a new FP sensor.

I find that when the fuel tank is full my press drops to 60-65, has the tanks gets lower & closer to MT the press climbs back up to 90PSI.

Is this a sign of my pump crapping out? Or maybe crap in the tank blocking the screen?
I never have any issues with the truck running, pulling hills or pulling a trailer. Nothing to indicate a lack of fuel.

Is it worth dropping the tank to check the screen? Or how do I test the Fuel pump?

Thanks for reading & any help possible.

 

I would tend to think it would be opposite: fuller tank = more psi and vice versa

Josh

 

Does the performance/idle change? Any possibility your gauge/sending unit is taking a $h*t?

 

It has me & the mech baffled. PSI goes up as the tank gets lower.
And why does Mech's gauge show 30PSI, my mech gauge 50PSI, the elec gauge in truck show 75-90PSI?

I have a new blue spring coming & a new sender unit for the elec gauge.
Will see what changes a new spring make & sending unit.

 

Is your sender mounted to fuel bowl or remote on something like the itp remote fuel sender hose which protects it from vibration?
air in the hose will cause higher pressure since the air compresses easily.

 

My sensor is mounted right on the bowl.

 

Just a quick update.
Got a new Blue Spring & FP sensor the other day.
I installed them today & found that the old Blue spring that I put in last yr was now much shorter than the new one. So it was weak or worn out.

New spring in & I get 60PSI on my manual gauge. Put new sensor in & it now also reads 60PSI.

Going for a road trip this wknd & see what goes on when the fuel lvl changes. Hope it was just a crappy spring & bad sensor.