Engine/Transmission (1998.5 - 2002) Fuel pressure

[Kalaehina]

I have a 2001 HO, with a FASS DDRP, my fuel pressure is taken from the top of the fuel filter. Idle I have 15 psi, freeway cruising 60 mph I drop to 12 psi, hard on the throttle uphill it drops to 10 psi. After reading through some of the forums, this seems a little low to me, should I be concerned? I'd like to make some mild upgrades to get some of the gitty up my 12 valve had, but I wan to make sure my fuel system is up to par first. Any suggestions? Thanks!

 

[JLandry]

Relax... those pressures are just fine.

As long as the pressure at the VP44 fuel injection pump inlet doesn't drops below 5 psi, there's nothing to worry about.

John L.

 

[Kalaehina]

Thanks for the info!

 

[Kalaehina]

Thanks for the info!

 

[Kalaehina]

Thanks for the info!

 

[drag racer]

Relax... those pressures are just fine.

As long as the pressure at the VP44 fuel injection pump inlet doesn't drops below 5 psi, there's nothing to worry about.

John L.

x2. you're fine.

 

[bry1216]

I understand the relief valve at the VP44 closes around 10psi which then cause cooling problems on the VP44.

Please let me know your thoughts on this.

Meanwhile I am looking for the nominal psi drop across the fuel filter.

 

[AllianceDiesel]

Actually the valve closes under 14psi. I don't like it to run anything under that.

 

[KATOOM]

The only valve on the outlet of the VP is the "overflow" return fuel valve. Its simplistic internal check ball and spring system is set to open at 14-16 psi. The valve is NOT an ON/OFF valve either as its never fully shut since there's a small 3/16" hole in the body of the bolt in order to allow a constant flow of excess fuel passing through the VP at all times. There's other considerations too as its thought that this overflow of fuel is coming from the mid-pressure chamber of the VP and the high pressure chamber cools by pushing an excess of fuel through the injector lines as that volume bleeds off and runs out the back of the cylinder head. Remember, the VP only cools itself via excess fuel over what the engine uses to run.

Years ago it was considered that any fuel pressure above 5-7 psi was enough. Then that though went up to no lower than 10 psi. But over the past 4-5 years its been considered that any fuel pressure under around 15 psi is too low and potentially is not offering the VP the volume of fuel to maintain coolest running temperatures. That said, with 95/150 GPH fuel pump we run today, in order to be able to maintain a WOT pressure of around 15 psi those fuel pumps shouldn't have to have the idle pressure set any higher than around 20 psi.

 

[SAndreasen]

I have a 2001 HO, with a FASS DDRP, my fuel pressure is taken from the top of the fuel filter. Idle I have 15 psi, freeway cruising 60 mph I drop to 12 psi, hard on the throttle uphill it drops to 10 psi. After reading through some of the forums, this seems a little low to me, should I be concerned? I'd like to make some mild upgrades to get some of the gitty up my 12 valve had, but I wan to make sure my fuel system is up to par first. Any suggestions? Thanks!

My truck is running a fass ddrp and a in tank pump I have edge juice with attitude and 276 injectors pro has been running that combo for 100,000 miles