1999 454 Suburban starting problem long Crank then start

[OZBIRN454]

Hi All I have a 1999 Chevrolet Burban 454 and sometime when I go to start cold or hot does not matter it it will crank for 4-5 seconds and then little black smoke out of the pipes and runs great after that. It has 114,000 miles I gave it a true tune up at 90,000 miles plugs, wires,cap, rotor,pcv, fuel filter. I have a scanner and no codes. I am going to check fuel pressure Tue. I did the fuel pump 2 years ago. I don't think it is the pump or pressure due to it runs fine after start up. It could be bleeding down right? Any help would be great thanks Jim

[2000CAYukon]

Black smoke = Too much fuel. My money is on the fuel pressure regulator.

Hook up a pressure gauge and turn the ignition on (no need to start the engine). After a few seconds, turn off the ignition and watch the pressure. It will drop a little but should hold pressure. If loose all pressure within a couple of minutes, the regulator is leaking or you have an injector leaking.

The fuel pressure regulator wear and the diaphram leaks fuel into the intake basically flooding the engine.

//2000CAYukon

[OZBIRN454]

Ok I checked fuel pressure and with engine off when you turn the key to on it peg to 67 psi then when the pumps stops it drops to 49 psi. When I start it and it is running it hold at 50psi Book says 56-62 psi so I am low but sometimes it will start no problem then sometimes it will crank for 3-4 seconds. 2 years ago I had a fuel pump done under warrenty from the chevy dealer . I hate to say thats it could it be the fuel filter or pressure reg? The black smoke out of the pipes does not appen every time either that only happenes on the first start up of the day. scratching my head need some help.

[2000CAYukon]

Originally Posted by OZBIRN454

Ok I checked fuel pressure and with engine off when you turn the key to on it peg to 67 psi then when the pumps stops it drops to 49 psi. When I start it and it is running it hold at 50psi Book says 56-62 psi so I am low but sometimes it will start no problem then sometimes it will crank for 3-4 seconds. 2 years ago I had a fuel pump done under warrenty from the chevy dealer . I hate to say thats it could it be the fuel filter or pressure reg? The black smoke out of the pipes does not appen every time either that only happenes on the first start up of the day. scratching my head need some help.

Well if the fuel filter has not been replaced recently, then by all means replace it. What did the pressure do when you turned off the key? You should watch it for 5 minutes.

49 is a little on the low side and can cause hard start situations. You really should be closer to 60. In order to test the regulator, you need to pull (and plug) the vacuum hose going to the regulator. With the vacuum line plug, the fuel pressure should go up to 67 or so.

On the 5.7 (in 99), the regulator is under the upper intake manifold. Not sure where it is on the 454 so it may not be easy to get at.

This sounds more like a fuel pump to me but you should really test the regulator to be sure.

//2000CAYukon