I did this myself and I do not enjoy these help columns, they are helpful but can get you into a pile of you know what. My 91 g20, you have to remove fuel rail. Disconnect gas lines 2 on the right side, you may have to cut to get off, take care not to bend the copper fuel lines they are attached to, this can be a chore. There were 4 bolts holding the fuel rail down, beware there is a plastic spacer between, the fuel rail supports and the engine, they are black and you don't even know they are there, they are 3.50 each at dealer, I lost 1 on removing on 1 when replacing. The electrical connectors can be a bitch to remove, I ended up squeezeing gently with a slip style plumbing wrench, put pressure on and pulled, maybe if you spray them with an electrical cleaner or carb cleaner first they may be easier. I bought 4 used injectors in a rail, they were a pain to get out, I used carburetor cleaner as a lubricant and kept twisting and pushing, this was a pain, they do not just fall out. I replaced mine without changing the o-rings they were so tight and I took care in removing, I just wanted to get it back together and to a garage if I had to. Mine were a pain also to get out of my fuel rail, someone must know a trick for this out there. Now here is a trick, you have to get the fuel rail on with the spacers, I attached the spacers to the engine using a heavy bearing grease, then carefully got the rail into place and fed four bolts through. For the gas part I disconnected the negative battery terminal, made sure there was no way to get it back to the battery terminal, opened the gas cap, seemed fine, probable should diconnect battery completely. Great place for parts is kingnissan in California, good luck, I would have someone else do it. Mine did work and is back on the road.
What is the order for removing the fuel rail bolts on a high port ('91 - '93) engine? Is there a removal sequence like there is for removing the upper intake manifold?
I found the correct sequence in the FSM , page 194. Starting on the radiator side of fuel rail: tighten bolts 1, 2 (from right to left), Then on firewall side of rail, from left to right. (then 3,4) Tighten all four to 7 - 8 ft. lbs. then to 15 - 20 ft. lbs.