hard starting

I own a 2000 GMC crew cab w/ the 7.4 bigblock, fairly recently it has become a little hard to start. Instead of starting the moment I turn the key I have to crank it for a second or two. It used to fire right up weather it was cold or hot, the rpms would go up to about 1500 ( I was told that that's when the computer is checking everything) then idle back down to about 650. Now, after cranking for a bit it sort of sputters and rolls into the 650 idle. Other than that it runs perfect. Any Ideas?
Thanks 75woody

I dont know if your truck has the same fuel system setup as my 99 GMC Sierra but I also had hard starting problems. The fuel pressure regulator turned out to be faulty. On my truck the fuel pressure regulator is located in line, on the left fuel rail. The fuel pressure is regulated by engine vacuum and a small tube runs from the regulator to the intake. A real quick check is to pull the little vacuum tube of the fuel regulator and check to see if its full of fuel. My regulator was leaking and it was sucking gas right into the intake. There should be no fuel in the vacuum side. I replaced my regulator for 55bucks and the problem was solved.
Anyway hope this helps your system might be different. Good Luck.
bob

My 1999 GMC Sierra had the same problem. The fuel pressure regulator was the problem. On the 4.8 V* its on the fule rail on the drivers side. Pull off a vaccume line and remove a clip. Pull out the regulator, its screen and a little O ring. A new on at the dealer cost me $72. After installing the new regulator turn on the key for 2 seconds the turn it off. Then turn it on for 10 seconds. Then turn it off. All this per the GMC repair manual. After I did all this my truck ran like new again. Good luck.

Hey Guys I'm experiencing same problem with my 1999 GMC Sierra 5.3L
Z71 pkg. Read the thread here and went out and picked up a fuel pressure gauge that I could connect to the Schrader valve. Here are results. Key on for 10 seconds I get about 46 psi at the fuel rail port on right side. Start and idle still about 45/46 psi on gauge. I've heard that it should be over 55 psi. Does anyone know what the pressure should be according to factory specs.??? I understand that filter or pump could also cause low pressure but based on threads I've read the fuel pressure regulator seems likely. Pulled vacuum hose off but don't see or smell fuel at regulator. Starting symptom is cranks and then fires but will come up from 300 rpm sometimes with stumble. Sometimes takes 3 or 4 attempts before running. It's got about 60K miles. Just replaced plugs with Bosch 6213's gapped to 0.060". K&N air filter. Tow's bass boat occassionally. Any info. appreciated.
Thanks,
Fred (old gearhead from 60's)

Picked up fuel pressure regulator at dealer. $100. No change in fuel pressure. Still reads about 46 psi on gauge. Did notice that with key on pressure rose to just about 50 psi. I think the pressure should be 55 to 62 psi. on this engine. Next step is fuel filter and then fuel pump. Has anyone seen this on their GMC Sierra or Silverado?????
Thanks for any info.
Fred

Fuel pressure is a little low. Replace the pump and that should take care of your problem.

My 2000 has about the same problem but it only happens when the engine has ran to normal temp and then let sit for 30-60 minutes. Starts fine when cold, starts fine when hot but not in between. No codes. I have been told to replace the idle air control valve but it works correctly when tested with a computer scanner machine. Also told to flash the computer but that seems strange to me also. Any other ideas, if not, I'm going to try the fuel pressure regulator like this thread suggest.

Thanks,

New symptom: 1996 Yukon, replaced fuel pump, filter (within last 3 months). Then engine code indicated running rich on both sides. Replaced fuel regulator. Diag codes gone. Engine runs great. New symptom: Many times I must hit the starter for many cranks before engine starts. I can leave it for a day. About every 5th day, it will start right off. Will start right off if I restart after about an hour. What did I do wrong?

Did you ever solve this? My 1999 has the same problem. Flashed the computer, but didn't help. Had the injectors cleaned, but didn't help... Thanks.





My 2000 has about the same problem but it only happens when the engine has ran to normal temp and then let sit for 30-60 minutes. Starts fine when cold, starts fine when hot but not in between. No codes. I have been told to replace the idle air control valve but it works correctly when tested with a computer scanner machine. Also told to flash the computer but that seems strange to me also. Any other ideas, if not, I'm going to try the fuel pressure regulator like this thread suggest.

Thanks,

Did you ever solve this? My 1999 has the same problem. Flashed the computer, but didn't help. Had the injectors cleaned, but didn't help... Thanks.

How did you flash the computer?
What method did you use to clean the injectors?
Is this an old body style pickup or a new Serria body style?

I did solve it. My problem turned out to be the fuel pressure regulator which costs about $50. Some other thread on here solved it for me but anyway, there's an easy check to see if this is the problem. Pull the vacuum line off of the regulator and if there is gas in the line, its bad. What happens is the pressure leaks off just enough that when warm it won't start but when cold, the computer knows that the pressure will have leaked off and compensates for it. Hope this helps...
Jason

Did you ever solve this? My 1999 has the same problem. Flashed the computer, but didn't help. Had the injectors cleaned, but didn't help... Thanks.

Is that fuel pressure regulator up next to the tank on the 99 silverado?

As I remember it is near the intake manifold. Look along
the fuel rail and you should see it. I have my old one which
tested ok. It's about an inch or less in diameter. Hope this
helps.

Thanks, I did find and it was the problem. Pretty easy fix, little pricey for just a little thing like that but what the heck ya gonna do?

I have an 02 Sierra 6.0 Liter that is having trouble starting when it's cold outside or after it has been sitting for a couple days. Pickup starts fine after it has warmed up or is being driven on a daily basis. Any thoughts/suggestions would be great