losing fuel pressure

[beerly]

I've searched to no avail. There is a lot of info on Gen I and II issues but I can't seem to find the answer to my issue for a Gen III. Prior to starting, the fuel pumps prime and I get 55 psi, but then the pressure slowly drops. I have to crank for about 8-10 seconds before the engine finally turns over but sputters a lot then runs fine. I understand this is probably an issue with the pressure regulator? But I cannot find a replacement nor anything about the pressure regulator in the FSM. My question is how do I fix this failure to maintain pressure at the rail? thanks!

2004 Paxton, Dual Walbros in tank

 

[beerly]

I assume the fuel is draining back into the tank from the rail. Anyone have an idea as to whether this could be due to a bad pressure regulator or the pumps themselves. I believe the pumps have a check valve in them so is it common to have pressure lost due to bad check valves in the pumps? I do have dual pumps in the tank, so if this is due to a bad pump check valve, do I need to replace both pumps or are dual pump systems usually plumbed in a series? I know there are fuel experts out there and that I'm not the first to experience loss of pressure at start up. Please?

 

[PaulP]

call todd at A&C performance 19516960500

 

[zombiesnake]

that does seem like a check valve gone bad, a pressure regulator would cause issues while running and so would pretty much any other fuel related part. the check valve is only really there for starting purposes and to keep pressure in the lines. im not sure where its located in this system but they can be part the regulator, near the fuel filter assembly, or at the pump

 

[mjorgensen Woodhouse]

I leaking injector could also do this and account for poor initial running.

 

[beerly]

How would you check an injector for leaks? Just pull each one and look for a dribble?

 

[mjorgensen Woodhouse]

Pull plugs and look for wetness and possibly use a scope to see if there is any fuel pooled in the cylinder.

 

[beerly]

Another question. I may have a shorted O2 sensor due to proximity to headers. If a sensor is shorted, could this prevent proper operation of the fuel system?

 

[mjorgensen Woodhouse]

Another question. I may have a shorted O2 sensor due to proximity to headers. If a sensor is shorted, could this prevent proper operation of the fuel system?

Not as far as leak down