Here is my situation. I recently purchased a 77 280z that had been sitting for a few years. I have read and search on this site and solved numerous problems on the car, but here we are with a problem that has got me stumped.
I have replaced/repaired the following that pertains to the fuel system:
Injectors
Injector connectors
fuel filter
removed fuel rail and cleaned and replaced all flex lines
new fuel pump with new flex lines from tank
all the old gas drained out and replaced (full)
fuel lines blown out from fuel pump to fuel filter
Here is the problem I am having. If the car sits overnight I can start the car and have around 34psi of fuel pressure. This continues for 3-5 minutes when the fuel pressure starts to drop until the car dies, of course. So, I am thinking there is possibly something broke loose in the tank and has partially clogged the fuel pump. I pulled the fuel pump and it was clear on the intake side?? Next, I placed a clear fuel filter inline just after it leaves the tank so I could see if any debris was coming from the tank, none so far. Here is the interesting part. Once I get enough fuel to prime the pump, and pressurize the lines to 34psi and start the car I can see that there is air coming from the tank into the fuel filter. This large amount of air causes the pump to cavitate and loose pressure. I have tried to lightly pressurize the gas tank to evacuate the air from the fuel line (since it has to go over the frame rail) but when I watch the see thru filter I see large amounts of air going into the filter instead of fuel being pushed thru the lines. How is this possible? Is the fuel pickup line possibly jacked up inside the tank? I have blown compressed air back thru the pickup line into the tank and it does appear to have blockage as gas spewed out of the gas cap.
Should there be fuel coming out a pretty descent rate once the air is evacutated from the line going over the frame rail?
Any help or suggestions would be greatly appreciated!
If I pull the tank will I be able to see the pickup line going into the tank? As far as I can tell the car has not had any damage to the rear, to suppect that tank has been modified.
Sorry for the numerous questions...
I do own the Haynes manual and Clymer manuals, and read the EFI Bilble numerous times (awesome info there). This site has answered many questions without having to post my own, thanks.