I bought a 1995 Blazer a few weeks ago. I knew it needed work, but it was fairly cheap so I thought not a problem. Its an LT with the 4.3 Vortec with about 168000 on it. After a little work, I am still having issues. Here is what has been done:

Turn signal switch replaced (Brake lights didn't work)
Some vacuum lines replaced
Trans fluid changed (Gasket was leaking)
Transfer case fluid changed
Differential Fluid changed
"spider replaced" (Due to gassy smell from exhaust and in oil, gas was pooled in the intake)
New plugs and wires
New shocks

So I'm a couple hundred bucks in and running out of money here. The check engine bulb was conveniently removed so now that I replaced it, it is on all the time. I can't get the codes. Got a universal reader from Oreilly on loan. It had all plugs (OBDI, II, GM, Ford, etc.) still can't read code. All fuses are good. Could I have an electrical issue? Original owner installed remote start and alarm but when I had the dash off to replace turn signal swtich everything was hooked up.

Also, I still get a rich gas smell from exhaust with some black smoke even after replacing the spider. Any idea what sensor this could be?

Thanks!!!

 

When you replaced the spider, did you also replace the internal fuel lines (aka 'nut kit')? If not, you may still have a leak inside the plenum. A fuel pressure & leak down test will help you troubleshoot this.

Looking under the hood, is there a large black or grey, finned metal box located on the passenger side inner fender? If so, your truck should be 100% OBD2 compliant. If not, then you may have what is commonly referred to as OBD1.5. If the later, it requires a scan tool capable of accessing this mixed bag of protocols. If the scan tool you are using does not specifically call out '95 model year GM vehicles in its list of compatible models, it likely doesn't cover the OBD1.5 vehicles.

The DLC should be powered by the AUX PWR fuse (Fuse #7 - 25A) in the I/P fuse box. Check to make sure that pin 16 on the DLC is getting +12V power. DLC pin view below:

 

Thanks. I will try that and let you know.

I did not replace the lines inside the plenum, they looked like they were in good shape and no leaks. I primed the system before I closed everything up, and the lines had no fuel on them. Although, I will agree that they could still be leaking. I'll do a pressure check to make sure.

As for the check engine light, I will check that fuse and the voltage to the pin. I will also read into the scanner I rented and see if it is compatible.

 

OK, so it looks like I have OBD1.5 to my dismay. The reader I had read 1995 specifically, and i even set it to my VIN code W. Still unable to read code. Going to trace some wires and see if something is cut or otherwise due to the installation of remote start and alarm. Will let you know.

My next question is, the double lip seal in the transfer case is leaking. So fluid from the trans is filling up the transfer case. What brand is the best to use to replace this? OEM or aftermarket. I only want to do it once.

Also, I can only find an O2 sensor AFTER the cat. Am I supposed to have one before it too? If so, I am unable to locate it. Where would it be so I can see if there is an empty hole or wire hanging?

 

You have an O2 sensor before the cat as well. The one after the cat is for catalyst monitoring only. The one before the cat is used for engine management.

I've never had a problem with National brand seals.

You might want to try another brand of scanner. Some say that they read '95 model year vehicles, but have fine print that takes out the OBD1.5 GM vehicles.