nissan 90 tldi starting problem

[dlr123]

I have searched the threads and couldn't find an answer. My engine was sitting up for 18 months. The electric FFP pump wouldn't run. So I replaced it and the mechanical fuel pump along with the fuel filter. I also cleaned the vapor separator. My engine won't fire unless I spray choke cleaner in the intake. The fuel pressure is getting up to 75 psig after long cranking time. The air pressure gets up to 70 psig after long cranking but won't hold after cranking, whereas the fuel rail will hold pressure. I change the air and fuel regulators. So, I'm hoping someone could tell me 2 things:
(1) What are the minimum pressures I need to crank (I do have spark)?, (2) How do I troubleshoot the issue?

Also, I don't have any codes stored in the ECM. Originally I had a few codes that said TPS fault. But I cleared those codes and cranked on it many times and no codes returned. I replaced the fuel tank hose and bulb.

 

[pvanv]

What is your actual model?

 

[dlr123]

NSD90A but ive found out that some parts belong to NSD90B

 

[pvanv]

Fuel pressure should always be 10 psi above air pressure. Air should be 80, fuel 90 +/-6. If both pressures are low, it is an air issue. Since the fuel pressure holds but the air does not, there is a possible air leak, compressor line, reed or gasket, air injector leak, or o-ring leak. If the FFP comes on for 2 secs, and raises the fuel pressure 5 or 10 psi when the key is turned on, the FFP is working. If not, the fuel regulator is suspect, or there is a restriction, such as a clogged HP filter.

 

[dlr123]

Thats great advice. I took the reed valves out of the compressor to look at them, but i couldnt tell. I hooked up an air compressor to the air manifold and try to crank it but no luck. It will fire for a split second if i spray carb cleaner in intake
My FFP does come on for a few seconds. I have disconnected the line from the high pressure filter to rail and hand bulb pumped it thru well.
Since it sat up so long i am worried about restrictikns within the fuel/air rail.
Didnt occur to me that i may have leaks in the air/fuel rail system. That looks a little complicated