I splicedin a pressure gauge just before the IP. I drove a couple of days and the pressure appears to be consistant. In the morning when everything is cold; When I turn the ignition to on and the LP starts up the fuel pressure reads 8psi plus or minus a pound. When I fire up the engine pressure drops down to 6psi plus or minus a pound. Later in the afternoon when it is warmer out 50s or 60s pressure drops to 3.5psi plus or minus a pound. When I am accelerating to freeway speeds the pressure drops down to almost 0psi.

Is this normal? what kind of pressures are yall seeing.

I am thinking that as things heated up the fuel thinned and the hose expanded resulting in the drop of pressure.

 

you want it to be around 5 even at wot

 

Try running with the fuel cap loose our caps need to breath if that dont make a difference you may be looking at a new LP or OPS.

 

If their is vacume in my tank is their a gas cap I could use that will allow the tank to breath?

 

If you have vachuum in the tank you have a problem get a new diesel cap