I got a 1999 K2500 7.4. I started having a problem when i would stop and cut off truck when i would restart it and take off it would spit sputter backfire and have no power then it would clear up and take off like normal. well i lived with it for a while until i dropped a lifter well i decided instead of just fixin lfter i would put some other parts in. i installed a new cam (comp cam towing cam) lifters ,timing chain, rockers,fuel regulater, stock distributor, ignition moduel,water pump,fuelpump etc. got it all back together got timin set . well i should have a lot ofpower increase but no. Comp cam said i should get better gas milage no lost 2 mpgs the other problem still exists but now its worse put it on scanner and shows no codes. any suggestions?

 

Did you check your fule pump pressure, or maybe injectors?

 

Yep - injectors if your fuel pressure is normal. They are very common to leak. I also didn't see a mention of fuel filter which a clogged one will cause some weird issues - trust me I know. The fact that it runs bad after shutting it off and restarting is a tell tale sign of injectors though. They leak when the truck is shut off causing a flooding issue until all the gas is burned then it will run better. You can remove the upper intake and turn the key on to prime the system and check each injector for being wet.

 

I changed the filter back when it started but made no difference would that cause a loss of power even after it clears up and cause terribble gas miliage I tow a 30 ft camper that weighs about 8200lbs stock gears 3.73 i got 7.5 mpg put in 4.56gears went up to 8.5mpg put in a towing cam and got 6.5mpg i have also purchased o2 sensors but have not installed them yet . my mechanic says my computer needs to be flashd this truck has never had a whole lot of power being it is abig block but with 4.56 gears and a cam it should burn the tires off i will definitely look in to the injectors.

 

It will definitely affect your power if they are leaking real bad. You may need a new tune (not just a reflash) to make up for the cam swap though. Give Justin at Black Bear Performance a call and he can definitely get you hooked up.
Another thing - when you swapped the distributor did you install a new one or used? Also how did you time it? These trucks cannot be timed with a normal timing light. You have to have a computer that reads cam retard and you want it at 0 degree's plus or minus 2 degree's. I learned this a while back when I swapped distributors due to a bad gear. I fought with it for about a week before finding out the proper way. I paid a local shop $50 to time it with their computer and it was like driving a new truck. We tow about 6000 pounds with a Suburban full of people through the mountains and unless we are climbing a steep grade it isn't even back their. It has 4.10 gears, but the tires are a little undersized so it is probably lower (numerically higher than that). We average 10 mpg towing and 12 empty.

 

We timed it with the snapon scanner it was a bear while doing it, it locked up his scanner twice he had the snap on man flash it andtold me to take it to the dealer and have them put it on there computer they did said timin was off (duh)he set the timin charged me 260.00 and said it was running great. haha not much afew weeks later my mechanic got brave and put it back on the snapon scanner timmimg was at 62 degrees as you know its very time consuming process because there is no room to turn distributer you have to keep pulling it out and moving a knotch we finnally got it at -1 it ran awhole lot better but this other problem still exsist . how do i get in touch with black bear perf. it does sound like a possible injector it has gottn worse it spit and sputters on cold start take offs and if u rev it up it beaks down at high rpms

 

Black Bear Performance :: Custom Tuning Solutions for 96 and newer GM Vehicles

I know you said you put a pump in it, but have you checked fuel pressure. These motors are fairly finicky about just the right amount of pressure. It should be around 58-62. Also there are some sensors that can be bad and not throw a code. If you can get your hands on your friends scanner again and read the live data that might point you in the right direction. A bad coolant temp switch comes to mind as well.