So I have a 96 blazer 4.3 vortec that's been having an issue starting. It'll crank and crank and crank then finally turn over. Sometimes it stays running, other times the rpms run clear up to 2k then drop to 500 before it bogs out. Ill then try to start it again with multiple tries and it'll finally start. I repeat this process until blazer decides to stay running. This is aggravating and wasting gas.

I've replaced the rotor, cap, plugs and wires, coil pack in the past 30000 miles. Less than that actually. Fuel filter was changed within the last year. I can hear the fuel pump kick on but could it still be malfunctioning? I've also cleaned the egr valve, maf sensor and checked all vacuum lines. I have no way to run a pressure test.

I'd appreciate any help.

 

The first place to start is to do a fuel pressure test. Most all parts stores sell the test gauge or even rent them so I'd start by picking one up and testing it because thats what it sounds like you issue is related to. Just because you can hear the pump kick on doesn't mean that its working or you aren't losing pressure somewhere else.

 

+1 on the fuel pressure test.

If you want to try a diagnostic that doesn't need a pressure gauge, try pulling the fuel pump relay out and letting it die from lack of fuel before turning off the key. Then, next start, put the fuel pump relay back and turn the key on for at least 5 seconds to prime the system before you turn it all the way to start it. If that makes it start better, you definitely need to do the full fuel pressure and leak down tests on the the fuel system. If that "fixes" (works around) your starting issue, you've got a pressure leak somewhere that's draining fuel pressure from your system, and it's probably leaking into the intake plenum, causing a flooded condition when you start.