Hey guys. Haven't posted in awhile. I've been to dealers, other forums..... still no luck. Praying someone can help me out before I throw more good money after bad.

I've got a 2000 S-10 Blazer 4.3L 4x4 with about 90,000 miles or so. I've owned it since it's had about 35,000 miles years ago.

I've searched online and found others with the same issue but none of the topics ever show a solution simply "try this, try that" etc.... and then they end.

When driving 90% highway with the cruise control set at a careful 65 mph I am still getting about 11.5 mpg. My gas light is coming on at about 150-160 miles. I've tried adjusting my driving style, religous use of cruise control, you name it, it ain't working.

Its been getting worse over the last year or so. Service Engine Soon light is on with a P0440 code -(EVAP Control System Malfunction). Except for the poor fuel economy, it runs pretty well. When I first got it, 16-19 would be average. If on a really long trip with the cruise control on I'd get 18-19+. Now, I'm amazed if I get over 13, and that hasn't happened in a loooooong time.

Other symptoms:
- If left in the garage overnight or over the weekend the whole garage STINKS of fuel. There are no leaks, puddles, or stains that I can see to indicate a leaky fuel line or similar. It's gotten so bad, I park it outside. I can't be 100% certain but it seems like the smell is stronger on the passenger side rear of the truck.

- I had the fuel pump replaced a year ago. It stammered and stuttered badly, especially in the summer. If left to idle with the A/C on, it would die within minutes. It still does but not as often.

- Replaced fuel filter with fuel pump. Fuel pump went again about 6 months later, dealer replaced again under warranty. New pump, new fuel filter and I always make sure the gas cap is TIGHT.

- I also occassionally hear a hissing noise when unscrewing the gas cap.


EVAP issues aside, could this still be the cause of such low gas mileage?

Thanks, sorry it was long but wanted to give you enough info to hopefully help me out.

 

My Blazer was getting similar terrible gas mileage even after i replaced the fuel filter and pump. the thing that really improved everything was replacing the thermostat, if the truck doesn't reach running temp then it sucks gas in effort to try to get it there. check to see if your truck reaches 195 degrees, if not maybe your thermostat is stuck open like mine was.

 

While the stock temp gauge isn't terribly accurate, it's readings havent changed since I've owned the truck. I'd think that if it was stuck open, I'd see cooler than normal readings.

Plus, I'm still left with the P0440 code too.

 

The fact that you mentioned you can smell fuel suggests that you have a fuel leak. You shouldn't be able to smell fuel even when parked in a garage-that's not normal. Perhaps it's a minor leak that only occurs while the engine (and fuel pump) are running.

 

Look under the fender behind the driver's side rear tire and see if that is where the smell of fuel is coming from. You'll see a black box with hoses running in and out of it. It is part of the EVAP control system. I'm thinking that is where your problem is and might be time to change it out.

 

I saw the box you were talking about and sniffed all around that area (felt like a goof doing it too ) and it seemed OK. I didn't see any cracks or loose/missing hoses.

When I stuck my head up over the driver's side rear wheel the smell got stronger and then I lifted up that little rubber flap that fits between the frame and the body and the smell got MUCH stronger. I think I'm getting closer.

It was hard to see in there but everything seemed OK...as far as I could tell. I believe I saw the two gas lines and there was nother wet around them or leaking.

Any ideas?

Perhaps I may have to give up and take it to another dealer *ugh* and see if they can just smoke it out and find the leak.

Would this cause such horrible fuel economy though?

 

Uhmmmmm, yes! If you can smell fuel, you are LOOSING fuel from the vehicle which means lower fuel economy! You should never be able to smell fuel coming from your car.

 

I had simular problems about a year ago. Ended up replacing the spider assembly. It was leaking gas into the upper manifold. Always smelled of gas and terrible gas mileage. I dont remember the codes it was producing, but I do remember they were always pointing toward everything regarding the emission. Took some time to figure out that was the problem because I was centered on anything to do with the emmissions. But once I replaced it the mileage was back to normal and the gas smell was gone. Good Luck, hope you figure it out since gas isnt getting any cheaper.

 

As soon as I can, I'll bring it into the dealer, I was hoping to avoid it. Thankfully, its a second vehicle so I don't need to drive it all the time.

I know its not leaking actual fuel, it simply the vapors I'm smelling. That's why I asked about the decrease in mileage. This seems like a big drop and based on my readings on EVAP malfunctions its more of an environmental issue than driveability.

I'll find out and be sure to report my findings for anyone else searching about this later on.

 

Please let us know what you find out.