i will repeat this tomorrow i thank everyone for todays help

 

I drove the blazer to work this morningit was still misfiring until I put it in passing gear and it would run
as soon as I let off the gas a little bit it came out of passing gear and started to miss again and was very verysluggish

 

Remove and check the fuel filter for restriction. You should be able to blow through it easily. Replace it if it's restricted. Then modify the fuel pressure tester so it will connect to the filter outlet and all fuel pressure and flow "dead ends" at the pressure tester. When the pump is running, pressure must be 73psi to 108psi, and it must remain above 55psi for at least 10 minutes after the pump shuts off. Post your results.

 

New filter after filter is key on 83 psi after 10 minutes key off 60 psi

 

codes P0101 and P0300 are coming up ???

 

Good job! The pump is fine, which means the leakdown is in the plenum. Now we know that the pump only drops to 60psi, which means any drop lower than 60psi, has got to be in the plenum. You had a drop to 42psi and a drop to 56psi, which is not a serious leak, but it is a problem.

To pinpoint the leak in the plenum, it requires installing a shut off valve in the return fuel line. To test: Make sure the valve is open. Activate the fuel pump to pressurize the system. Simultaneously deactivate the fuel pump and shut the valve off. If fuel pressure holds with the valve shut off, the regulator is leaking internally and needs replacement. If there is any drop in pressure below 60psi, the spider assembly needs to be replaced.

EDIT: The P0101 and P0300 could be caused by the fuel delivery problem, so fix that first.

 

i rechecked the new 315 dollar spider assembly i installed already and cheched fuel presure at rail again when i puuled the upper plenum i must have not had the fuel line tight because there was a small amount of fuel up on top at the rail i have key on 62 psi 10 minutes key of 52psi now it ran a little better on the way home but still not right

 

Could be that the O rings on the fuel lines were leaking, and that would explain the excessive leakdown. Clear the DTC's from memory and drive it. If the light coms on, retrieve the codes and post them.

 

idid all this after work and cleared codes got home with my borrowed scan tool and ran codes and got o2 sencer code and p0300 also p0101

 

1) What was the DTC for the O2 sensor?
2) What order were the DTC's retrieved?
3) Does your scan tool allow you to view fuel trim?