98 Z71 cranks then dies, then cranks and runs fine

[banshee350twincyl]

I have a 98 Z71 with the 5.7. About a month ago when i first bought it i when to crank it in the morning when it was cold and it cranked then died immediately. It did this 2 or 3 times then it cranked and ran fine. And then i didnt have this problem anymore. Now yesterday morning it did the same thing, this morning it cranked first try. I dont know whats going on. I did a major tune up last weekend, fuel filter, plugs, wires, cap and rotor, ATF filter and flush, rear end oil change, coolant flush, pcv valve, oil and filter change and air filter. I was thinking that it could possibly be the battery acting up. or maybe the fuel pump starting to go bad, any help would be appreciated.

[NY_Z28Man]

Probably not the battery cause if that started acting up your truck would crank really slow or just click. When you get on it do you feel a loss in power? Also turn the key to run and make sure you hear the relay click the pump off before you crank. It takes like 3 seconds or so. Then try cranking and see what happens. I just wouldnt rule out that fuel pressure regulator.

[banshee350twincyl]

Thanx alot for the help, do you know how much a fuel pressure regulator costs. And where in the world is it located , the haynes manual doesnt give me much info on the regulator. Ya the relay does kick the pump off after about 2 seconds. Thanx again for the help

[NY_Z28Man]

Its been a while since I've done one but I would say anywhere for 10-20 bucks. The tricky part is getting at it if you have a vortec motor. I wouldnt even bother with it unless you can determine the fuel is leaking back to the tank. Id get a fuel pressure gauge on it and see if when you turn the key on and the pump shuts off that your fuel system holds pressure. Its upwards around 55-65 pounds I think. If you can find a rubber section of the return line take a pair or needle nose vise grips and clamp off the return line then see if it does it when you first crank it (just dont keep it clamped for very long). To me it sounds like your truck just doesnt have enough fuel to take off meaning lack of pressure. Or the ignition is week so your engine cant get a hot enough spark. Letr me know how it goes. I'd just check that fuel pressure before you go changing the regulator. That thing sucks to get at it's under your upper intake manifold. Take Care Man, Good Luck, and Merry Christmas.
-Paul

[Tagahoe]

I have the same problem. Some times it starts up fine, sometimes it will crank and turn, but wont start. I've done a tune-up, fuel pump (filter is about 4months old), and fuel pressure regulater (fyi: costs about 50 bucks and is located in the manifold; look up manifold in the Hay. book, i think its there). After replacing the fuel pres. regulator it worked fine for a few days, now it wont start again. Turns over and over, but wont start. WHAT IS IT???

[NY_Z28Man]

When you replaced the regulator did you replace both o-ring gaskets( one around the outside and a small one on the inside). Sometimes the little o-ring on the inside can break or lose seal and you'll lose your fuel pressure. Clamp off the fuel return line and see if it runs then.