2000 Silverado with delayed starting

[Bama72]

Truck history: 2000 Chevy Silverado, standard cab, 4x4, 4.3L, manual shift, 140,000 easy miles.
I started to notice a loss of power and mpg (mpg was down to 13 combined, it has always been around 19 combined). So I decided to replace the spark plugs, plug wires, distributor cap and the rotor (all acdelco) since they have been on the truck since new. While replacing the distributer cap and rotor I looked inside my throttle body and it was nasty. I replaced the stuff already listed without trouble.

Before replacing those items I could turn the ignition on, wait for the fuel pump to turn off, bump the starter and the motor would crank immediately but the motor would run poorly. Now I turn the ignition on, wait for the fuel pump to turn off, hit the starter and after 7 or more seconds the motor will crank but it runs really good.

I went to pick up a throttle body gasket the next and on the way to the parts store my service engine soon light came on for the first time ever. Since it wasn’t blinking I kept driving to the parts store. At the parts store they checked the light and it was a bad Mass Air Flow sensors. So I left with a throttle body gasket and a new Mass Air Flow sensor. Got home, disconnected the battery, replaced the MAF sensor, took the throttle body off and gave it a real good cleaning. About two hours later I connected the battery. I went to start the motor and it had the same delayed cranking.

Here is my dilemma: Before, the truck would crank quick but run poor, now it cranks poor but runs like it did when it was brand new. Do any of you guys have any ideal why the motor is slow to crank? Should I not worry about it since it does crank and runs like a new motor?

Thanks in advance for any help.

 

[sweetk30]

96-up vortec style need specific psi on fuel pressure within 5-6 psi range. if not there thay will fire off hard and low power.

also known for pressure reg going bad and doing bleadoff bad. or not hold pressure.

and need to check psi to go farther.

install a gauge that will do min 70 psi as its in the 60 range if i recall. then cold not started in a few hrs key on no crank like you prime all the time. see/record the psi . then watch and see if it hold psi. then crank to start and watch it should be in the max range to start then level off to normal.

when running whats the psi ? if its to low = hard start/low power.

i had a 4.3 s-10 in the shop few years ago. pump was week and truck would start hard / run like crap. installed now pump after we found bad pump from tests and like new truck.

and if you have mass air problems and run oil style filter like k&n oil buildup from filter on mass will cause stumble on cold start take off and little problems as the oil acts like a coolent on the sensor thats heated to tell air flow over the heated eliment.