Hello everyone.

I'm new so bear with me. I bought a 2001 Blazer ZR2 fixer-upper for a few bucks a little bit ago and got it running fairly well, but as of now I am having an issue that has me scratching my head. I replaced the original CSPI injector unit and old regulator with a new updated MFI injector unit and regulator and didn't replace anything else aside from the plugs, oil, oil filter and fuel filter and plenum gaskets. There was an issue I found the rotor in the distributor that was an easy fix which cleared the P0300 code I was having at the time for a day or two, while I was checking the rotor I checked for play in the shaft and noted there was no horizontal or vertical play in it and found a little play on the rotational axis of the shaft but it was pretty minor and moved maybe 2 tenths of an inch from full stop one side to the other side. When I ran uptown to a gas station (barely half a mile) a few days later and parked it for 5 minutes while I ran inside I came out and started it but its usual powerful first crank jolt had a pretty sharp decline starting with low effort while seemingly choking and reeking of fuel. I made it home and it just died out and refused to start so I just went inside and pondered the possible change that occurred in a few minutes that would cause that drastic of a change. I came back a day later and popped off the MAF sensor connector and turned it over it started immediately without issue with plenty of unburned fuel catching and burning I shut the vehicle off and wanted another opinion so I headed over to my old mans house and spoke to him about the change. He thinks its the MAF sensor and I have a strong inclination to believe him since I plugged the MAF sensor back in and had an immediate change to impossible to start unless I gave it some throttle but I unplugged the MAF sensor and tried it again no change but I may have not given it enough time. I have previous live data results from my OBDII scanner but the only thing I could find out of the ordinary was the TPS was a straight 0% on a run to the nearest down 10 miles away. I didn't have any issues with the blazer previously aside from power issues at 60+ MPH but that was due to a damaged converter which I removed for the time being until I get a new one. I'm at a loss because I am caught between the EGR, TPS, MAF and coolant temp sender between the numbers 3 and 5 cylinders as I have read that could cause issues. I only have the P0300 code that reappeared and the P0101 code that popped up along side it. I cannot feasibly believe the new injector unit and fuel pressure regulator to have failed at this point neither that the converter has caused this issue.

Any input would be much appreciated. I will be putting some time into testing voltages and resistances at connectors on the wire loom under the hood here in a few days to see if there might be a short somewhere or a bad ground.

Thank you for your time.

(Some additional info: The blazer sat for a number of years without being ran regularly and the gas was quite old really having been used as a light plow truck. I used treatment and isopropyl and dumped in new fuel and ran it for awhile which cleared up a lot of the old nasty gas. I got a second bottle of treatment for the second tank after I run this old tank through.)

 

Sounds a lot like a TPS to me. I'd start by testing that, then moving on to the MAF and others after that as needed.

 

Much appreciated vectorz, i pulled one off an old throttle body along with an IAC to test both. Will be fiddling with it tomorrow when it warms up a little.

 

So update. New TPS and new IAC and the issue persisted, old man came and looked at it but it was flooding so we undid the fuel pump and it started running normally without cutting out. We tested the leads to the spider and they all showed wide open (no noid detector so we couldn't be sure) we unplugged the spider and same result ran fine by sipping fuel from the tank under vacuum pressure alone. We grabbed a fuel pressure tester and it jumped to 60 pounds after putting the relay back in place but it dropped immediately after we figure its possibly the injector unit and regulator went bad so im gonna RMA it and try another one. I have an mp4 video if it running with the pump and injector unit unplugged and a pressure reading but i was not able to post it here.

 

I put videos on youtube and link them.