Hello,
This is my first post, so far i have liked the site. I have spent the last couple hours reading through all the threads trying to find stuff i could fix on my Blazer. I bought the Blazer about two months ago. It is the vin "Z" 1990 4.3L S-10 Blazer with 309,000 miles on it. When I got it, the engine ran well, i noticed that there was some carbon coming out the exhaust and there was a fuel smell upon deceleration. I looked at the engine and i decided to start with the vacuum system because i noticed a vacuum line just kinda hanging out. I took off the PCV valve and disconnected the hose from the valve and tried to blow through it, nothing. I sprayed carb cleaner in it until all the carbon (there was a lot). Then i looked at the MAP sensor hosing, it wasnt as bad but i still cleaned it. Next came the evap canister hosing. I ended up replacing the hosing and the canister because the hosing was cracked and the canister was damaged. The throttle body was also so badly clogged that the vacuum system was unable to suck out of the PCV line, or the evap line. So now the throttle body is all clean and all lines are clear. This stopped the black soot (carbon) from coming out the exhaust, but the fuel smell persists.

I guess the only thing that is left to check is the EGR valve, and i have also heard of a purge valve for the evap cannister. I cannot visually see any leaks on any of the fuel lines.

The Blazer is currently getting 13.1 MPG running on 85 octane. Tonight i went out to the blazer to do the self diagnostic, it did not report and error codes, then i did the feild test (while the engine is running the test tells you if the vehicle is running in open loop or closed loop and then also tells you if it is running lean or rich). The engine ran in open loop until the engine heated up, it then turned to closed loop and reported that the engine was lean. So no error codes and engine running lean, yet there is this fuel smell.

personally this post is to long, but i wanted to say everything. I dont know how to test the EGR valve and I dont know where the evap canister purge vavle is on my vehicle. I have also read about this Sea Foam, i dont know if that would help. The chiltons manual states that the ECM relies heavily on the coolant temperature sensor, I have a new one, but if the one thats on there is bad wouldnt the computer throw an error code? Does anyone have any other ideas?

one last thing i just changed the oil, oil filter, air cleaner, spark plugs, distributor cap and rotor, new antifreeze.

 

I personally would concentrate on the fuel leak. If you've got a good nose then you should be able to find it. A full blown tune-up will most likely improve your gas mileage but....with a fuel leak this will throw everything off so...concentrate on the fuel leak. Look aroug with a lighted match...JUST KIDDING!!! Good luck-keep up posted. Look at fuel lines from the tank to the TBI. Look closely near where they run on your truck near the powersteering reservoir-where they come up-have seen them leak(rust thru-partially) near there. JP