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Originally Posted by _gforce57
Hi guys. This is my first time on the forum. Hope one of you smart guys can give me a hand on this problem. I have a 1996 GMC Sierra 3500 with a 454 cu. engine. I bought it back in October and have noticed since that it starts very hard. By that I mean I have to crank it four to six seconds almost every time I start it.
Sometimes on morning starts it starts right off like a good gm should. The big problem is after I have run it for a while then shut it down for about twenty minutes. Then crank, crank, crank. If I start it within that first twenty minutes it starts right up.
I have taken it to the local gm shop and they replaced the fuel pressure regulator. That didn't do the trick. Brought it back and they thought they noticed a knock sensor code so they changed that. Still no good. The poor truck has been back to the shop six times and they still haven't figured it out.
Head scratcher eh?
The fuel pressure during cranking is at 55 pounds then drops off to about 50 pounds while idling. After several minutes to an hour I noticed the fuel pressure is between 20-30 pounds.
Could the fuel pump be the problem? It is my understanding that the fuel pressure should be 55-61 pounds during idle. Or do I need to look at a different cause.
Appreciate your time,
Gerald
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When you turn off the key, it is the fuel pressure regulator's job to maintain the correct pressure in the fuel rail. Typically, hard starts after being shut off for 20 minutes, can be a bad fuel pressure regulator or an injector or two that is leaking. Fuel leaks into the cylinders and floods the engine causing the hard starts.
Either the new fuel pressure regulator is bad or you have one or more injectors leaking. The pressure should not drop to 20-30 lbs after a few minutes.
//2000CAYukon