Initially the vehicle was running poorly, hesitation, week throttle response etc, replaced cap, rotor, wires, plugs and it failed to start. rechecked wires for timing position no help. Replaced coil, no help. Replaced ignition module engine fired up but only ran rough for two to three minutes then died. Rechecked fuel pump pressure and verified 59 psi on new gauge. Pulled/grounded plug and spark looks weak.

 

What brand of parts did you use?

 

Any codes?

 

Mostly Duralast parts but there is another problem, I can't read any codes (haven't been able to do that for 13 years with this vehicle). I got it to start (briefly) using carb cleaner so I check power at the intake manifold tuning valve assembly and there isn't power on either wire so I think it might be an ECM issue. Any ideas would be appreciated.

Unfortunately for the 13 years I've had this blazer I haven't ever been able to read codes.

 

If you have the OBD1.5 setup, then you need a scan tool capable of reading the OBD2 type codes present in the PCM. The OBD1 type codes can be read using the info found in the link below:
How to read obd1.5 codes

 

Initially the vehicle was running poorly, hesitation, week throttle response etc, replaced cap, rotor, wires, plugs and it failed to start. rechecked wires for timing position no help. Replaced coil, no help. Replaced ignition module engine fired up but only ran rough for two to three minutes then died. Rechecked fuel pump pressure and verified 59 psi on new gauge. Pulled/grounded plug and spark looks okay. Shot carb cleaner in the plenum and vehicle will start but dies. Checked power at the intake manifold tuning valve assembly and there is no power on either wire with the ignition in the start or run position.

 

The MTV should not cause a no start condition. All that it does is modifies the intake path to allow for air to be shared from side to side for better high RPM breathing. The MTV valve is opened when requested by the PCM and gets its power from a relay mounted to the firewall which gets power from GAUGES (20A) fuse. The ground for the valve is located on the top/center of the intake manifold.

It sure sounds like you have a fuel issue. Have you tested pressure?

BTW, lets keep the discussion to one thread that way people do not have to go searching for what has already been done/discussed/suggested.

*Merging back into previous thread*

 

I actually attempted to simply update the initial post but wasn't totally sure how to do it correctly.

Checked fuel pressure, at the rail, and had 59 psi. I even disconnected the output side of the (new) fuel filter and filled a container. After reconnecting the fuel line and cranking the engine as much as I did I would think the plugs would be wet but when I pulled one the plug it was dry.

 

The CPI engines have been known to have the injector harness internal to the engine fail. Try gently pulling on the wires that exit out of the front of the intake under the throttle body. I believe it will be a blue & pink wire.

 

CPI? My truck has a multi port injection system, which I replace about six years ago. I'm really at a loss with this problem. I don't want to continue to shot gun parts, as I have with the coil, ignition module, along with the typical parts (plugs, cap, rotor, wires, etc.) that I just recently replaced. Any help is appreciated.