gas mileage

I know this has been posted before but I couldn't find it. Sorry
Anyways 96 Blazer 2 door with flowmaster muffler and I am getting 13 mpg. I was getting 16-17 a couple months ago and since then it has gone down hill. What do I do to gain it back.

13 !?!?!?! :eek7:

Geez I have 100% stock and routinely get 18-21 mpg on my 99 4.3L...and that's with 160K on her....

Do you still have the stock MAF...??

13 !?!?!?! :eek7:

Geez I have 100% stock and routinely get 18-21 mpg on my 99 4.3L...and that's with 160K on her....

Do you still have the stock MAF...??

K I am a CARB guy so I don't know fuel injection stuff, what is the MAF, and I think I have the stock one, I haven't replaced anythign but the muffler and yes 13 sucks I was getting around 16-17 in town, and 19-20 on hwy just a while back.

K I am a CARB guy so I don't know fuel injection stuff, what is the MAF, and I think I have the stock one, I haven't replaced anythign but the muffler and yes 13 sucks I was getting around 16-17 in town, and 19-20 on hwy just a while back.


Well need to know when you ....tuned vehicle up....
Wires, cap , rotor, etc...?
How many miles on the motor ?
What type of motor ?
MAF = Mass Air Flow Sensor......your air intake coming to the throttle body...

Just wondering, is it running smooth ? Did you change anything else ?
I am sure others will pipe in once you tell us more about this motor...?

Did you take off the cat or disconnect an air sensor on the exhaust and it's constantly dumping more fuel in.....??

Tell us more...

Well need to know when you ....tuned vehicle up....
Wires, cap , rotor, etc...?
How many miles on the motor ?
What type of motor ?
MAF = Mass Air Flow Sensor......your air intake coming to the throttle body...

Just wondering, is it running smooth ? Did you change anything else ?
I am sure others will pipe in once you tell us more about this motor...?

Did you take off the cat or disconnect an air sensor on the exhaust and it's constantly dumping more fuel in.....??

Tell us more...

84000 on the motor and haven't done wires, or cap, etc. 4.3 motor and the MAF is stock unless it got changed before I bought the vehicle. I am going to put a highflow cat on but havent done anythign yet because I want to know what the problem is first.

You need to do a complete tuneup.

You need to do a complete tuneup.

So what is the complete tune-up. Spark plugs, wires, and cap.

AC Delco Platinum Spark plugs gapped 0.060
Cap & Rotor
PCV valve
Air Filter
Fuel Filter
Plug Wires

Important things you should also do:

Transmission flush an fill with a new tranny filter
New transfer case and front and rear differential fluid.

Just in case he means new transfer case FLUID not a new transfer case :lol2:

Just in case he means new transfer case FLUID not a new transfer case :lol2:

OOPS! Yes, transfer case fluid.

Your check engine lite on??? With that low mpg it sounds like it might be on

Your check engine lite on??? With that low mpg it sounds like it might be on
no check engine light.

would like to know if tune-up helped. I have never been able to improve mileage on any modern (electrconic ignition) vehicle I have ever owned that was running smoothly by replacing plugs, cap, wires etc. I always do it anyway -- but it never works. I think that especially in the case of wires and distributor cap (which are quite expensive these days), routine replacement might not be the way to go in most cases. Just looking for opinions. I will probably never break the tune-up habit I picked up when a teenager woking on cars with carbs and ignitions with points and lower voltage.

would like to know if tune-up helped. I have never been able to improve mileage on any modern (electrconic ignition) vehicle I have ever owned that was running smoothly by replacing plugs, cap, wires etc. I always do it anyway -- but it never works.

Lemme throw out a few options:

Spend the $40.00 bucks, get the computer scanned using a semi-decent scan tool, you want to know:

1. Are the O2 sensors active and not sluggish. You should see values like 0.2 up to 0.8 volts. Bank1 Sensor1 and Bank2 Sensor1 are used to control your fuel mixture if memory serves. The other two are around the CAT. The O2 after the cat should be fairly flat. At 85,000 KMs, your O2s should still be good. They normally last around 100,000 Miles.

2. Are you getting any missfire conditions while driving?

3. Some other item not thought of? Ask whoever is doing the scanning.

Other then this, we come back to the basics:

4. Is the exhaust clear of obstuction? Clogged cat maybe?

5. PCV Valve failed causing a pressure buildup in the engine?

6. Kids stealing gas from the tank! :nono:

7. New plugs and wires and cap and rotor. But if you aren't seeing any
missfires, I can't see this helping.

Grasping at straws, we come to

8. U joints starting to Seize up. Are they hot after you go for a drive?

9. Transmission service, bands tightening, new oil, new filter.

10. Flat tire.

11. If you hear 'clicking noises' it could be a lose spark plug wire. Check
for ARCing.

Regards,
----- Robb -----

Would best to first do the proper engine tuneup procedures and maintanence before you start to look into the computer diagnosis.

Would best to first do the proper engine tuneup procedures and maintanence before you start to look into the computer diagnosis.

Only thing I would add is a professional fuel injection flush and a throttle body cleaning. I had my tuned up two weeks back and was getting about 375km's per tank. After the full tune up and the cleanings I've gone through two tanks and getting between 475- 550km's tank and much better throttle response.

K I did the tune-up last week and I am still occuring same gas mileage. The only thing I didn't do was the PCV Valve. I'm not sure what that is or where it is at, any help would be good. There is also an odor coming from my vehicle, it smells bad but isnt familiar.
Thanks

K I did the tune-up last week and I am still occuring same gas mileage. The only thing I didn't do was the PCV Valve. I'm not sure what that is or where it is at, any help would be good. There is also an odor coming from my vehicle, it smells bad but isnt familiar.
Thanks

Is the smell like rotten eggs? If so, I would have your catalytic converter inspected. A clogged cat will rob power and fuel efficiency.

PCV valve = Positive Crankcase Ventilation valve. It should be located in a grommet on the valve cover with a piece of hose connecting it to the intake. It's a spring loaded check valve and it should rattle when you shake it.

It will be in the driver's side valve cover.

Did you reset the computer to relearn the fuel curve?

To reset the computer, put the key to the on position and remove the two ECM fuses in the fuse panel.

I have been following this thread for a while my 95 blazer exhibits the same problem with fuel. 131k getting 12mpg in city and 18 hwy. new plugs, wires not cap and rotor. New tranny filter fluid. Fluids else where are clean and within 10k sinse last changing. I did get the check engine soon lamp on. (It should glow a $$$ instead of check engine soon!) I have the injectors cleaned using profession cleaner. The engine light lit on a trip then went off a day later, ran smooth and idled well. At times it hunts and peck at idle, very slightly though. I have heard of 3 things to do and not sure about 1, clean EGR, read other threads and not 100% sure exactly what that means. Is it the butterfly valve that leads to intake of engine. And 2, option is to monitor fuel pressure regulator? Ghhhh? What the heck it that? 3 to reset 'puter. Any more suggestions? Thanks Chris

First off, how old is the cap and rotor?

You need to use the search feature for:

EGR valve

Fuel pressure

These have been discussed several times before in this section. I would read the threads about the 1992-1995 4.3L W vortec.

To reset the computer, turn the key to the on position and remove the two ecm fuses in the fuse panel and wait 5 minutes or so.

he has a carb so there is not much a o2 sensor would do look into proper settings on carb

I have some of the same problems with my 95 Blazer. I get like 25 mpg on the highway, but i can like watch the gauge go down driving around town. I have replaced the plugs, wires, cleaned the cap, replaced the rotor, feul regulator,feul boss, air filter, ect. But the engine still has a rough idle??? Any input.

I have some of the same problems with my 95 Blazer. I get like 25 mpg on the highway, but i can like watch the gauge go down driving around town. I have replaced the plugs, wires, cleaned the cap, replaced the rotor, feul regulator,feul boss, air filter, ect. But the engine still has a rough idle??? Any input.

What plugs did you use.

Replace your cap, don't CLEAN it.

Replace your air filter.

Replace your PCV valve.

Ever checked your CPI injector for leaking?

I used ac delco plugs, replaced the filter and pcv valve, and i have been cleaning cpas forever. Thats the only way that we kept the irrgation motors going for years on end. It all works the same way. The cpi dosnt leak either.

Replace the cap.

I have a question for you. Are you ASE certified?? But here is my reasoning for not replacing the cap. If the contact areas inside of the cap are not all burnt up or have chunk missing out of the contact points you can clean some of the white crap off with some fine emory cloth and it is as good as new. Farmers would go broke if the suspected the cap was the problem every time a well motor went down. Its just cheaper and just as eficcient.

I have a question for you. Are you ASE certified?? But here is my reasoning for not replacing the cap. If the contact areas inside of the cap are not all burnt up or have chunk missing out of the contact points you can clean some of the white crap off with some fine emory cloth and it is as good as new. Farmers would go broke if the suspected the cap was the problem every time a well motor went down. Its just cheaper and just as eficcient.

No, I am not a ASE mechanic , and nor do I have to be to state that replacing a cap with a new rotor is a smart thing to do. How many mechanics clean a cap instead of replacing it? Few to none.

You are just being cheap and trying to warrant your logic which is just incorrect.

filing off the corrosion will increase the gap from the rotor conductor to the cap conductor and increase the gap which the spark has to jump.

And yes, a small difference will cause problems seeing the system is engineered for certain tolerences.

That white corrosion is the metal being oxidized. It is not a layer of material appearing out of no where. When it corrodes, the cap conductor is erroded back. Filing off the oxidization does NOT bring the cap back to factory state.

This will cause increased resistance in the ignition system and the plugs not getting the spark which they require for optimal economy and ignition.

And please stop comparing this engine to a farm tractor.

If I was comparing to a farm tractor i would say tractor engine. I am comparing to a well motor. This is a motor that pumps water from the ground, not a piece of equipment, and range in sizes for 4.3liter to the gm 454 and bigger.

If I was comparing to a farm tractor i would say tractor engine. I am comparing to a well motor. This is a motor that pumps water from the ground, not a piece of equipment, and range in sizes for 4.3liter to the gm 454 and bigger.

Sure, whatever comparison.

My other facts still hold there ground as smart tuneup procedures without cutting corners.

filing off the corrosion will increase the gap from the rotor conductor to the cap conductor and increase the gap which the spark has to jump.

And yes, a small difference will cause problems seeing the system is engineered for certain tolerences.

That white corrosion is the metal being oxidized. It is not a layer of material appearing out of no where. When it corrodes, the cap conductor is erroded back. Filing off the oxidization does NOT bring the cap back to factory state.

This will cause increased resistance in the ignition system and the plugs not getting the spark which they require for optimal economy and ignition.

And please stop comparing this engine to a farm tractor.


well said do a tune up

the conductors in a cap are coated with certan alloys filing removes alloys reducing conductivity and life that is why u have to clean the cap alot

well said do a tune up

the conductors in a cap are coated with certan alloys filing removes alloys reducing conductivity and life that is why u have to clean the cap alot

It is all about the distance.

The bigger the distance, the more the resistance.