Why my V6 3.1 wastes so so much gas.????

Things i changed, to try to help reduce the gas consumption, and still nothing.

1. All fuel injectors
2. All spark plugs
3. All spark plug wires
4. Ignition module
5. Distributor cap
6. Air filter
7. Fuel filter

And my gas tank does not leak.

i drive normal a total of 50miles in the city and burn a full tank of gas.
That is real crazy it eats more then a v12.

Some one can you please help me.

 

wow. well with that kind of comsumption, does it have any drivability problems?

 

I don't see checking your timing in there....very important.

 

O2 sensor. $20 and it's probably time to change it, even if it's not your main problem.

 

See the thing is, i also changed the o2 sensor like a month ago and the check engine light still stays on i tried disconnecting the battery for 15min so it can reset it self but nothing happened it still comes on and stays on.

 

see that's just it, it rides fine just when idling it seams to go up and down the rpm but very light.

the car seams fine but its far from it with this type of gas consumption.

 

See now this is one thing that i did not do.

i am going to talk tomorrow with someone that has a timeing gun

 

OMG and i thought my 250 miles per tank was bad!


Um well your on the right track of fixing the problem. Honestly though. Everything that has mentioned will help....i think you have a leak somewhere.


THERE is NO way that your car would burn THAT much gas for that many miles. You must have a leak. Double and triple check that you dont have a leak. Do you smell gas at ALL when its sitting or driving or anything. If you smell it while your driving you, for sure, have a leak somewhere. It might not be in the tank but could be in any of the lines even the return line. It could be at the back of the manifold. It could be anywhere.



Also while I thought of it. What injectors did you use to replace the old ones. What brand and what flow rate?

 

Sure it not leaking from the lines, like the return line.

 

well when its parked i have the car on/running and see no leaks, but i do smell a lil gas some times when i drive in traffic but very faint.

 

See what the code is for the check engine light. That could narrow it down quite a bit.

 

i had this problem to man
both the EGR and O2 went bad
change the egr and O2 then seafoam that bad boy and u should be good

 

Sounds to me like either a vacuum leak or a MAP sensor problem. More than likely a MAP sensor problem since the light comes back on after the system is reset and not having been run...

Need that code!

:edit: I used to be there... My car was getting that kind of mileage when I first bought it (with the factory 2.8 and all sorts of crap screwed up under the hood). Hated filling it up to go 35 miles to school (using half a tank to get to the cheapest gas station in the area halfway there) and having a quarter tank left when I got home...

Replaced the engine, ECM, most of the sensors and ALL of the fuel injectors and ignition parts, and now I get 400+ per tank when I want to...

 

milage that bad has to be a leak, i had a leak but the smell wasnt strong.
it ended up being the charcoal canister.
when you undo the petrol/gas cap is there a hissing sound or woosh of air as the tank equalizes with air pressure ??

 

Well, when I had my 98 V6 Firebird I had a major power loss and I started getting horrible gas mileage. Turned out to just be a collapsed catalytic converter. Just an idea you may want to check out. Also check to see if you have an exhaust leak somewhere (maybe a cracked exhaust manifold?). But still even if you are having those problems I think you'd still be getting better gas mileage. The only thing I can think of that would make for such horrible gas mileage is things that have already been mentioned such as a vacuum hose leak or a fuel line leak. I know you said you changed your filter but did you check to see if your Fuel pump was working correctly?

 

no

 

i have all new pipeing

 

How much do you take at fill up?
Only thing I can think of is dented tank....

 

First thing I would look for is vacuum leaks. It might not even be the lines. It could very well be a gasket that has dried out and hardened. Touch all the lines. If black rubs off on your hands, they are toast. Check also the PCV elbows on both valve covers. They have been known to crack and leak as well as that big plastic vacuum fitting in the back of the lower intake manifold. Second, if you are smelling gas at idle or right after the car shuts off, your canister purge solenoid may be to blame. If it is stuck open all the time, it will purge constantly. This is a big waste of fuel. Take the canister off and see if it is full of fuel. If it is, its shot. The fuel pressure regulator could also be to blame. Last thing, just a quick question, when you installed your new injectors, did you use new O-rings and did you lube them before putting the injectors in the car? If not, one or two may have chaffed or rolled up causing a vacuum leak at the intake manifold. This will make you rip out every last hair on your head trying to track it down.

 

i put a new fuel regulator, and my injectors i put them in fine, the reason why i even put the new injectors was because it wasted so much gas.
i had some one do a vacuum leak check on the car for me and they said there is no leak he even double checked.

today im going to check the canister and let you know if thats it.

Thanks.

 

if its real empty i put about 34$ to fill it up but im always around 28-30 dollars to fill it up

 

i checked the canister and it had no fuel what so ever in it.

 

so if fuel is pouring out the bottom of my charcoal canister my purge solenoid is stuck open?

 

This is usually caused by having the return and vent lines reversed at the gas tank.

RBob.

 

thanks RBob

 

no hissing, venting when undoing the cap is a leak.
take the rubber hose from the canister to the metal fuel pipe, tank vent - take it off, block off the metal pipe and use it like that and see what happens, that will tell you if its the canister or not.
sounds like it though

 

and that hose to the metel fuel pipe "tank vent" should not fill with liquid gasoline correct? Should only be vapors that reach there as far as i'm understanding.
switched my hoses around on the only two that could possibly be incorrect at the tank, one goes to a breather back there another goes to the fuel filter, if one going to fuel filter was wrong then no gasoline would reach my engine i'm guessing.
I had repaird one fuel line, replacing it halfway as other end whent up and around my transmission ( I know believe to the canister) When I was replacing it there was fuel in the line, and a vacuum occurd, wich was no fun as I had to hold the line from gasoline pouring out while i woorked ont he other end of the line. So maybe the same line was going to my canister and this vacuum was causing it to spill out my canister. Gonna drive her and cross my fingers

 

So what If I am getting a hissing sound from gas tank when cap on and when I take cap off extreme back pressure release and strong smell of gas, and horrible gad mileage with a misfire at low RPM. It stared after I changed a bad injector I had diagnosed and after rebuilding the distributor. I can't pin point it. I get about 112 miles to the gallon. Real crappy pick up in low range but once it going it drives fine.

 

112mpg, DAMN! What do you get when its running bad?

 

lol... yeah I see my mistake 112 miles full tank. I normally get around 350 miles per tank. It has a rough idle around 600-750 rpm when first starts. But hey it just passed inspection it surprised the hell out of me. I just took it today for inspection because I want to drive it more so I can try and figure out what might be going on.

 

The return line sounds restricted.

 

So I found a tank pressure valve and a vapor valve on ebay for 30 bucks came together. I just got it in and will put them in this weekend I am just posting a heads up to pass along what I find out. I have been driving the car for the past week and I noticed when I drive with the gas cap loose it does not misfire unless I go from a stop or slow down and try to accelerate. Also, I noticed the engine is running warmer than usual. It is getting about 220 degrees when sitting in traffic and it not normal. the fan will kick on and keep it from getting any hotter than that. Just not normal... It is running pretty rough. I will pass along anything I find out. Will see if the fuel valves I got help out with any of the symptoms I am experiencing.

 

n stock GM had these things run well over 200, temp gauge don't go red till 260, but keeping the temps under 200 will make it run better.

if AC is shot, remove AC rad and make sure the airdam is in good shape.

I only fill up to half a tank, got almost 100miles on the trip counter n over 1/8 of tank left.

 

Wouldn't a vacuum leak cause a weird idle?
I'm thinking egr valve.
I want to delete mine ( custom chip might be cheaper )
And just wanted a cleaner engine bay. No smog BS here on my 92.
I wish I knew if there was a resistor that could by-pass the egr.

 

I have trouble code 32 which is EGR Failure... so I have taken egr off to check for clogged carbon but none was found I still cleaned upper intake and the metal tube from egr to intake. I went ahead and took egr off and sprayed choke cleaner down the mount to exhaust manifold. What can I do to trouble shoot the EGR valve itself or should I just replace it?

 

I got the same code. Replaced the egr ( not cheap ) erased the codes, went for an 80+MPH drive, when I let up off the gas the code popped again. Turns out it was the wiring harness was fubar.
Check the connections before paying large amount of beer funds on an expensive part only to find out it was something almost under $20 and easy as possibly splicing or soldering a broken wire.

 

Ok so I have changed the EGR, got one on ebay for a decent price. I am getting a smooth idle and stays that way even after it warms up. Also, the hissing sound is gone after driving; was either the tank pressure valve or the vapor valve. I have not driven it for 60 miles to let computer get adjusted, but I am still getting that misfire or premature detonation in low RPMs. (stop to go, or into a turn) One new thing it doesn't start on first crank like it was now I have to attempt 2 or 3 time before it turns over. Strange??? I am happy to see some progress though, not shaking when sitting and more quite.

 

holy crap this post is old. Is the OP still following this?

 

RSB913.1 did alittle hi-jackin', without saying "I don't mean to high jack this thread but my car is doing...."

 

Yes I guess I did Hi-jack this thread I did a search on my symptoms and this page just seemed to match all my symptoms. I figured I would update the issue if I found the solution...lol. My bad!

Any who the original symptom was horrible gas mileage and hissing. I found that when I changed my tank pressure valve and vapor valve hissing stopped, but gas was still horrible came across bad egr and now my gas mileage seems fine(but not fully tested have not gone through a whole tank yet), now I am getting a new issue... MAP sensor code 33. My Car will just turn off under acceleration. It will drive fine if I keep the acceleration at a constant rate but if I push it sputters goes crazy and turns off. which is why I have not fully tested my gas mileage.