hey, quick question. when it says to set your fuel pressure at 42 psi for a certain result, is that fuel pressure at idle with the vacuum line connected or disconnected? if it reads 40 at idle, and i disconnect the line to adjust it, it jumps to 50. naturally the vacuum would drop at WOT, causing fuel pressure to spike. if anybody has any feedback on this, id appreciate it.

 

42psi with engine off, or regulator vacuum disconnected at idle.

 

Vacuum disconnected from the regulator and engine idling.

 

so what should the pressure be once the vacuum hose is reconnected?

 

43 ish

 

is that 43 when the hose is connected and engine running?

 

Hose disconnected and engine running.

 

well, ive got aq holley afpr, and if its at 40 with the engine idling, and then i disconnect the vacuum line, it jumps up to 50

 

Set it with the vacuum disconnected because the idle is dependant on other variables.

 

well, at idle with vacuum disconnected, its near 50psi. anyone know what the limit is on how high the pressure can go? ive got a holley fuel pump, but i would hate to blow a fuel line apart, being as the feed and return lines are stock

 

Stock regulator will blow at 65.
Why are you so high and wanting to go higher?

 

so lets say i set it at 42-43 with hose disconnected what should it be once the hose is reconnected?

 

~39

 

to answer your question, viprklr, im at 40 at idle, which im pretty happy with. when i disconnect the line, it spikes to 50. im under the impression that when the car is at WOT, it is a 50 as well. i have a holley regulator as well, but there seems to be a 10 psi difference between idle and WOT. when will the fuel feed line blow?

 

It'd probably take more pressure than your pump can supply to blow the feed line.
That's a big jump. My holley afpr only moves 4 psi between connected and disconnected. Maybe my low vacuum could be the reason for that though.

 

mine was at 45.5 with the car running and the hose connected. been that way ever since ive got the car?

 

mines @ 36-38 and it won't start. doesnt it need 40plus to start??

 

My factory regulator is 47 psi with the vac disconnected.
89 F motor.

 

22lb/hr injector pressure rating is 3 bar/43.5psi
At WOT a 22lb/hr injector should flow 22lb, but if the pressure is 38psi it's only flowing 20.5lb/hr, at 47psi it flows 22.8lb/hr.
Higher flow is preferable, but not much more than 10%.
A MAF ECM can adjust for a 10% increase either way, but the Injector depends on the pressure for good atomization and a good cone pattern.