Hi I got a 2001 Chevy blazer Lt with a 4.3 vortec engine. When I first start it, it could start or it could take a few tries. It will idle rough and then choke up and want to quit so I have to keep it at 2000 rpms, anything under it will cause it to quit, when it does quit it will try to start but won't get past 500 rpms. I've replaced map sensor fuel pump sending unit spider injection ignition control module fuel rails. can someone please help me

 

Look at the coolant sensor temp the PCM is seeing, using a scanner. Sound like flooding. but if you've replace the injector spider there isn't that much that can cause this. Is it blowing black smoke? If so the coolant sensor bad causing the PCM to think its -40 outside can do it. Don't just throw a part at it.

 

One possibility (and I stress possibility), a bad or damaged crank position sensor will exhibit those symptoms pretty much exactly. Check the wiring as well as the timing chain cover at the bottom to make sure they haven't been damaged in some way. WARNING: if you disturb the crank position sensor you will have to take the truck to someone with a capable device to do a crank relearn procedure. So don't just remove it to have a look-see.

 

Fuel, Vacuum/Compression, timing. Check all those parameters, one of them will be off.

Check engine light on? I want to lean toward a timing issue as well. Why did you put on an ignition module? Did it actually go bad, or was it just in chance that would fix it? I went through 3 ignition modules because the distributor on my 95 was burning them up.

Also, being you replaced the spider, the fuel regulator couldn't be an issue, unless it's not getting the correct vacuum. Like Lesmyer said, the ECTS could cause the engine to dump fuel as well. Likewise, I say hook her up to a scanner with live data and see what you get. Check cam and crank correlation while you're at it. Either could be bad.