I've got a 1995 Blazer I'm working on with a few problems that I can't diagnose. It has the 4.3l CPI motor that has been replaced once before.

There are no codes.

The motor runs rich but the O2 sensor is showing lean on the scan tool. It also has an erratic idle that doesn't even out when driving. We can't find any vac leaks and everything else indicates all is well. The owner recently had the plugs, plug wires and EGR replaced but that didn't help.

Also, the vehicle will randomly unlock itself while sitting and driving. The switches have been gone through with no problems found. I'm thinking it could be the remote unlock relay going bad. Is there anything else that could cause this?

Any help is always appreciated.

 

Sounds like you have a bad MAF sensor, or worse yet, an intake manifold gasket leak.

 

Those motors don't run a MAF, they're OBD1 speed density.
Pull the intake top, most likely you have a leaking regulator, or fuel line

 

A leaking return fuel line is exactly what we found.

 

It's a common issue with those motors. I saw one leak so much fuel through the number 3 cylinder, the exhaust caught on fire. I couldn't believe it didn't hyrolock up the motor.
Glad to see you got it fixed and thanks for posting the results. I wish more people would. A lot of times I wonder if they ever got it fixed

 

yeah, I hate that on forums when results aren't posted.

The entire left side of the intake was filled with fuel. And you're right, it is a small wonder it didn't hydrolock.

 

The Blazer has returned with yet another problem. The ABS light has come on. No codes can be seen by the scan tool.

The ABS sensors were packed with grease and grim. All have been clean and nothing obvious can be seen.

Is there a way reset the light? Battery disconnect hasn't worked yet. And, should the light blink a code as in early OBD1 vehicles?

 

The ABS light should reset after ever start. If I remember correctly, those blazers had an issue with the ABS wiring getting wet and corroding the connectors. Pull allthe conectors apart and clean them, then fill them with electrical grease and plug them back together.

 

Is there a procedure for doing the reset aside from disconnecting the battery?

And where are the codes physically stored for the ABS system?