I was wondering if someone could help me out. I have a 99 chev 3500 dually with a 454 fuely in it. The last month I have had major starting issues. I have installed new plugs, cap, rotor. Brand new injectors, temperature sensor for the ECM unit. Also changed the multi-function switch. Sometimes when the truck is turned over it wont fire. Most of the time I have to floor it to get enough fuel to start it. I have had numerous mechanics and dealerships look at it and cant seem to figure out the problem. This problem isnt all the time, one day it will fire right up and others it just wont start. I dont know what else to try. Let me know if anyone has any suggestions. Thanks  

have you looked at the MAF sensor? also, look at the oxygen sensor. if not try there. Also i don't think flooring it does anything. With fuel injection, you only get fuel when the motor needs it, so i don't think that action gets more fuel to the motor.

No but if the fuel pump is starting to go bad i.e. the pressure is dropping off then it will make for rough starting conditions but then you would think that it might have some running problems also. Unless of course the battery isnt in the best of shape. i.e. the voltage drop of cranking affects the pump that if I rem correctly is stuck in the tank. I think I heard somewhere that the newer GM rigs(yes that is still new to me) require like 20+ lbs of fuel pressure to run.

Id tap into that line with a pressure guage and find out what its pushing and how steady it is and if it changes with cranking.

When you figure it out youll have to share what the problem was. My '96 half ton had a similar sounding problem, and I changed a fuse, and fixed the problem. A dealership would surely catch that, though.

I believe that "flooring it" will shutoff the fuel pump on fuel injected applications.  Perhaps the problem is too much fuel?   

my suggeston would be to trade it in let someone else deal with it  but i dont know i still only own good ol carberated pre computer stuff never owned a car or truck newer then 1972

If pressure is dropping off, I would suggest it might be the fuel filter that is typically inline somewhere along the frame rails under the truck.  As far as the electric fuel pump goes on these, it is my unfortunate experience to know that they don't "gradually" loose pressure.  They pretty much work or they don't. 

Case in point was my 78 Suburban that we were on a trip with in the eastern part of our state.  Stopped at a store in Spokane, Wa to pick up ice and some pop for the kids.  Truck ran great into the parking lot.  Got towed to the Chevy dealership ten minutes later.  It never ran until they installed a new pump and filter for a measly $400 bucks.

Case two was when I took my 77 Iroc to the emissions testing station for it's bi-annual check.  Ran great the entire way until I got into line.  Engine died - Two days, $600 bucks, and a tow charge later, I went back to try the test again.  It passed, but not till I was red faced over the deal. 

I do know that the fuel pump is run off of a ignition acuated relay that should be on your fire wall just above and to the left of the distributor.  If you can get a wireing diagram and find out the relay that controls the pump and put a test light on the output side of it, it wll at least tell you that part of the system isn't the problem.  If the relay is intermittant (works most of the time but not every time) then the relay may need to be replaced.  Much cheaper than a fuel pump.

Just hope this can help you out some.  I have been frustrated on this type of thing twice and know it can be the craps to figure out.  Good luck, Bowser.