Well I finally did mine today. For months I've had a gas smell that came and went, and was occasionally strong. I had cleaned my fuel injectors and replaced all the O-rings a while back, but didn't do the cap (same O-ring). Of course that's where the leak was, so today I went back in.
I took the opportunity to also replace my power steering reservoir. I've been hearing some funky noises and we'll see if that helps.
• To improve access, I removed the two spark plug wires nearest the reservoir from the distributor cap, and two vacuum fittings from the intake manifold.
• Remove the two easy-to-see 8mm bolts holding the power steering reservoir.
• With a good light, get eyes on the nut below the reservoir that must be loosened slightly (NOT removed).
• Coming from behind with ~5" of extension, get a 10mm socket onto the nut and loosen it.
• Pop the reservoir up and out of the way enough that you can access the fuel rail cap.
• I did not disconnect the battery or drain the fuel system. Perhaps because of my leak, there was no residual pressure.
• It was difficult to pry the cap off. I used a couple of wide flat screwdrivers and as someone mentioned, I used the power steering reservoir mounting bracket for a leverage point. I knew I didn't want to risk permanent damage to the cap's integral spring clips.
• Swapped the O-ring and reinstalled, only to observe a serious leak, maybe 3 drops per second!
• Popped the cap off again and fiddled with the spring clips for a while, trying to find the happy middle where the cap is held tightly but will slip on with moderate pressure. If you bend them too far in, you cannot press the cap back on.
• Finally reinstalled the cap. I was not happy with the way it wobbled and did not seem like a snug fit, so I took a heavy cable tie and wrapped it under the fuel rail and over the cap, and tightened it down.
• So far no leak at all is visible. I'm not sure the cable tie is necessary, or how long it will hold, but time will tell.
Here are the additional steps to complete my power steering reservoir replacement:
• Use pliers to move the two hose clamps, one on the smaller return line and one on the larger supply line.
• It took some effort to loosen both hoses by twisting, without risking damage to them.
• With an empty plastic milk jug handy, pull off the hoses and catch what runs out of the filter and the reservoir. With attention to orientation of the reservoir, little should run out.
• Put the new reservoir
in place and attach the large hose and return its clamp to the proper position. At this point you can also tighten the 10mm nut and replace the two 8mm bolts up top that hold the reservoir in place. Replace the spark plug wires onto the distributor.
• Plug the small fitting on the reservoir. I used a small piece of hose with the opposite end held up to the top of the reservoir. This does not need to withstand any pressure, just to prevent the fluid from running out.
• Route the small return hose into the milk jug. A high flow will hit this, so be sure it's secure.
• Add fresh fluid to the reservoir, right up to the top. Turn on the engine and rock the steering back and forth a little. It will only take seconds for the old fluid to be pumped out and chased by the new fluid. You'll feel and hear the loss of power steering as the new fluid is drawn in, emptying the reservoir, and pumped back out into the milk jug.
• Remove the plug from the small fitting and attach the return hose and place its clamp.
• Refill the reservoir and top it off as needed after running the engine and exercising the steering.
• I had bought 2 qts of fluid for the power steering, and most of the 2nd quart is leftover. I could have used more for flushing, but I really don't think it would have done much more. I could not have done the job with just one quart, so you really need to buy two.