Looking for someone that knows the in's and out's of vortec's csfi (spider) fuel injection unit. Originally blazer was running super rich. Narrowed the problem to the cpi unit. Pulled it apart and found the regulator was bad dumping fuel into the intake through the vacuum port. I didn't trust the unit due to the hoses and poppet valves being melted and carboned up so i replaced the unit with a salvage part. Now I have cyl. misfires on 2 & 6. Right bank compression ranges from 155-170. I installed a new plug in 2 and, no change. I switched 2 & 4 plug wires, no change. I ohmed out the injectors both at 12 ohms(spec 11-13). I have signal to the injectors. I'm thinking maybe the poppet valves aren't opening. Is there any way for me to tell that the cylinder is getting fuel? Greatly appreciate any help given. Thank you. ****UPDATE**** Problem solved. I think the poppet valves must have been sticking due to the unit sitting on shelf for awhile. I pulled the plug wire off and ran it for a minute, then rechecked the plug and it was dry. It quit misfiring after running and shutting it down a few times. Took for test drive and all appears ok. Thank you for looking, I couldn't find how to delete the post so I just updated. Maybe the info may help someone else. Thanks again. GO BUCKEYES.

glad it's working! and thanks for posting the fix!