i am having trouble starting my99 4.3lblazer i replaced distributer cap rotor button, wires, plugs and fuel filter i done a fuel pressure test it shoots up to 62-65 then dropes to 55-56 all it will do is crank.
now i might have another problem i disconected the wireing harness clips from the computer to inspect them ,and no i have been told because of this i have to get the computer reprogramed is this true
thanks guys in advance.

 

I highly doubt that you have to get the computer reprogrammed simply becuase you disconnected the harness. If this was the case, all of us would have to get our trucks' computer reprogrammed everytime we replace or disconnect the battery. All the programming of your computer is stored on EPROM chips which are non volatile and do not require power to keep their programing.

As far as your staring problem, is your Service engine soon light on? If so, what codes are you getting? Have you done a leak down

 

If that was true, then I would have thousands of dollars invested in reprograming ECMs or PCMs.

It will fall back to factory default and then will relearn when you do get it started up.
Try checking your wires and make sure all the clips are back where they should be.
Its always a good idea to mark them when you pull them. As with my 95 I saw that some of the clips can fit in the wrong slot.
So I tagged each clip with the color socket they go back into (and numbered them on paper).

 

Here is a photo fromt he GM Service Info DVD I have:



(1)
Vehicle Control Module (VCM)

(2)
Right Front Fender

(3)
VCM Connector (Blue)

(4)
VCM Connector (Clear)

(5)
VCM Connector Retainer

(6)
VCM Connector (Black)

(7)
VCM Connector (Red)

(8)
VCM Retainer

[IMG]local://upfiles/1127/D4FA82A4BE964E89A7CDFAFBB9FDC57F.gif[/IMG]

 

thanks guys it turned out to be a ignition coil ,, it was getting spark to the plug but i guess not enough anyway it runs now , thanks for everyones help