Z_Dust Posted April 23, 2007 Share Posted April 23, 2007 When I turn the key on my 77zt MS-II, you can hear the fuel relay click and the fuel pump winds for a few seconds, pressure climbs to just shy of 40lbs, then the fuel pump cuts off and the fuel remains at around 35lbs. All good so far, right? As soon as I turn the ign swithch off the fuel pressure drops instantly to "0", nada. If I leave the ign on, the fuel pressure drops very slow and seems to stop around 30lbs. I have a factory turbo fuel pressure regulator and a 95lbs rated fuel pump. I have 0 to 60lbs fuel pressure gauge on the retun side of the fuel rail, before the FPR I have an after market fuel rail and new stock flow (not factory) injectors Fuel Damper? FPR? Quote Link to comment Share on other sites More sharing options...
gjc5500 Posted April 26, 2007 Share Posted April 26, 2007 Im not sure but i think thats about right. hopefully someone will chime in on it. since the fuel system has a return to the tank, as soon as the pump goes off, all the fuel would return no 0psi. im just thinking but im sure that makes sense. Quote Link to comment Share on other sites More sharing options...
Z_Dust Posted May 1, 2007 Author Share Posted May 1, 2007 I'm pretty sure the system remains presurized even after shutdown. Thats why you should apply voltage to the cold start valve prior to servicing the fuel system. This will release fuel into the intake and bring the pressure down so you dont get a nice fuel facial when disconnecting the lines. I believe it also ensures that the next time you crank the car it will start right away since the lines are already pressurized and the fuel is ready to "go". Or I could be wrong ....... Quote Link to comment Share on other sites More sharing options...
TimZ Posted May 4, 2007 Share Posted May 4, 2007 I'm pretty sure the system remains presurized even after shutdown. Thats why you should apply voltage to the cold start valve prior to servicing the fuel system. This will release fuel into the intake and bring the pressure down so you dont get a nice fuel facial when disconnecting the lines. I believe it also ensures that the next time you crank the car it will start right away since the lines are already pressurized and the fuel is ready to "go". Or I could be wrong ....... That is true with the stock fuel pump, as it has a check valve built into it. However, aftermarket pumps might not. Mine don't and my fuel system acts the same way. Quote Link to comment Share on other sites More sharing options...
Z_Dust Posted May 4, 2007 Author Share Posted May 4, 2007 It is an after market fuel pump. Unless I hear otherwise I'll just leave it as it is since it doesnt appear to be hurting anything. Thanks Quote Link to comment Share on other sites More sharing options...
dj paul Posted May 4, 2007 Share Posted May 4, 2007 i put a carter check valve on my system, its technically supposed to keep constant pressure. Part # 169-1002. keeps pressure at right above 30 psi Quote Link to comment Share on other sites More sharing options...
Z_Dust Posted May 5, 2007 Author Share Posted May 5, 2007 So how far from the fuel pump do you place the valve? Did you use 5/16 barbed fittings on both sides of the valve to connect it to the fuel line Quote Link to comment Share on other sites More sharing options...
dj paul Posted May 6, 2007 Share Posted May 6, 2007 i put it right after the fuel filter in the engine bay, it would be a little bit better before the filter. I just used 2 3/8 flared fittings from a compressor hose and teflon tape to hook it up. Quote Link to comment Share on other sites More sharing options...
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