I have a 93 s10 blazer 4.3 vortech. Last time I checked mileage in town it was less than 10 mpg. Trouble code 45 (oxygen sensor rich) pops up when engine is under load for an extended period of time. I replaced o2 sensor. No difference. It has pretty rough idle and occasionally will diesel when you turn it off. If you power brake it on pavement ( without spinning tires) it leaves a circle of soot on the ground. Wasted fuel. When you turn cruise control on check engine light comes on right away. I am leaning heavily towards the map sensor. From what I have read in books and learned from people that I have talked to. Any help would be appreciated.

 

Have you checked the fuel pressure? Somehow you are getting more fuel into the cylinders than the PCM can account for.

Do you have TBI or CPI?

 

Don't know what your problem is, but just checked my '95 today and it got 17.xx mpg on a mixture of hiway and city driving.

Good luck!

 

I have CPI and no I haven't checked fuel pressure. I do know that when I bought the blazer about a month ago and changed the spark plugs the driver side bank were heavily fuel fouled(thick black build up), passenger bank was much better.

 

It is very possible that your FPR has failed and is dumping raw, unmetered fuel into the intake.

 

Do you know if it is possible for intake to drain into only driver's bank in all three cylinders? I read in another thread bout drain holes in manifold that affected rear cylinder on both banks but nothing on all cylinders on one bank.

 

I do not remember the configuration of the CPI intake. I'd have to take a look for some pictures to be able to answer that. One thing that I know for sure is that there is only 1 fuel injector in the CPI motor so if it were the injector, it would effect all cylinders. You could have some bad luck on the poppet nozzles on that side, but again, it shouldn't be that lopsided.

 

Well I am having this problem too. Not to your extent but according to a java mpg calculator I get 12.78 miles to the gallon. Before I just filled it up I added fuel injector cleaner into the gas to see if that helps. I bought a fuel efficiency chip also to see if that will help. Any suggestions to get better mpg would be grateful. Am I running to rich?

 

Not to go off-topic, but what 'fuel mileage chip' did you purchase? Most of them are smoke & mirrors...

 

So what should be expected mileage per gallon in Blazer? I have 12 mpg driving only in city and short distances (up to 5 miles). Is it OK? Or should I check my oxygen sensor?

Marcin