Fuel Pressure question
Thread Starter
Burning Brakes
Joined: Apr 2005
Posts: 1,227
Likes: 0
From: Atlanta Ga
Fuel Pressure question
Im converting my 81 over to TPI. I got my fuel pump installed and have pressurebut i only have 40 psi at the check valve. Is this enough for a TPI system? I was thinking i heard you needed at least 45.
will i be ok?
will i be ok?
Melting Slicks
Joined: Oct 2002
Posts: 3,193
Likes: 1
From: Cincinnati Oh
kind of depends on whether or not you have engine vacuum to the pressure regulator, and if you've messed with the regulator screw at all (they can be adjusted).
40psi is on the low end of "acceptable" and should actually increase with engine RPM due to the loss of manifold vaccum. If you disconnect the vaccum hose to the pressure regulator while the engine is running, then it should be higher (having atmospheric pressure/no vaccum tells you what the "real" fuel pressure is).
Also, running the fuel pump with only 12 volts (engine NOT running) versus engine running (get more like 14 volts to the pump) will decrease the maximum fuel pump output and could cause pressure drop-off under WOT conditions - but again the actual line pressure is determined by the pressure regulator on the TPI fuel rail.
40psi is on the low end of "acceptable" and should actually increase with engine RPM due to the loss of manifold vaccum. If you disconnect the vaccum hose to the pressure regulator while the engine is running, then it should be higher (having atmospheric pressure/no vaccum tells you what the "real" fuel pressure is).
Also, running the fuel pump with only 12 volts (engine NOT running) versus engine running (get more like 14 volts to the pump) will decrease the maximum fuel pump output and could cause pressure drop-off under WOT conditions - but again the actual line pressure is determined by the pressure regulator on the TPI fuel rail.
Last edited by Ramanstud; Mar 10, 2006 at 07:24 PM.
