1997 GMC Sierra Hard cold start

With 55 lbs pressure it should n't be a fuel pump but. Before you start it check to see if you have fuel pressure by taking the cap off and just pressing on the schrader valve. It may be losing pressure after it sits for a while. There was a problem with those fuel pumps and if you get a delco they supply you with the harness that needs to be replaced at the same time. It's about 12" long that went bad.

If you are talking about the egr valve, it would make it run rough not start. But you can clean them sometimes and get away with it. But one thing I did forget was the cannister purge valve. IF that is stuck open it may not idle at all and effect cold starts. It is only supposed to open at 30 mph and above. And easy test for it is to block the line going to the tintake with a screw or bolt. If the other ting I said don't work. The only other thing I could think of woul d be the sensor in teh distributor giving your problems. You should be able to test that with an ohm meter though.

See whathappens when you retire? Lol. Ya the poppet valves and lines will give you trouble as they had a tendency to break/crack the lines and would effect the spraying into the cylinder. I don't rmemeber how exspensive they are though.

You do know that it could be the main injector that feeds them as well. I'd take it to a pro to havehim check it out to make sure it's the problem.