BAD gas mileage.

by 74MonteCarlo Sun May 08, 2011 8:29 pm

I'm getting horrible gas mileage on the Monte since it went back together. There are no apparent gas leaks. The dwell is right on 30 degrees. My uncle suggested advancing the timing. It was at 8 degrees per the emissions sticker, so we advanced it to 15 degrees. I drove it 18-20 miles today to my aunt's place and home, and burned over 1/8 of a tank. It was never that bad before! Does anyone have any suggestions that could help? This is killing me!

by BlackChevelleSS Sun May 08, 2011 8:42 pm

check EGR and did you rebuild the carb while it was apart?

by 74MonteCarlo Sun May 08, 2011 8:43 pm

No. Took the carb off, put it on the shelf, and put it back on.

by JB2wheeler Sun May 08, 2011 9:57 pm

Did you cover it up to keep the crawly things and general dirt out of it? JB

by 74chick Sun May 08, 2011 9:58 pm

Do it. Q-jets hate to sit.

by 74MonteCarlo Sun May 08, 2011 9:59 pm

Mmm, no.

by 74MonteCarlo Sun May 08, 2011 10:00 pm

74chick wrote:Do it. Q-jets hate to sit.

Do what?

by ss2323ss Sun May 08, 2011 10:43 pm

Q-jets are cranky sometimes... The shaft that the butterflies are on can get some slop and throw the air/fuel mixture off. It may need a rebuild..

by 74MonteCarlo Sun May 08, 2011 10:55 pm

Oh, forgot, turned in the mixture screws too.

Yeah, I was thinking about a rebuild. The one that's on it was rebuilt a couple years ago. It's not the original, but I do have THE original.

by pila Sun May 08, 2011 11:43 pm

I guess you could send the original to Sean Murphy for a really good rebuild.

by ant7377 Mon May 09, 2011 7:40 am

It might be the actual gas .Try a different place. Just because you never had a problem with it before dosent mean you wont this time. THese days fuel quality is garbage,try an additive maybe it will help.

by 74MonteCarlo Mon May 09, 2011 8:24 am

I get gas at only one place, in all three of my cars. The '74 Monte is the only one with slipping mileage.

by JB2wheeler Mon May 09, 2011 9:19 am

There is the little matter of alcohol content, the more there is, the worse your gas milage is. They claim the lower cost of the gas will make up for the lost milage. If you believe that, I have a nice bridge I will sell you real cheap. Why so cheap? It needs painting. JB

by The Dude Mon May 09, 2011 9:58 am

How's it running? Anything noticeable like exhaust fumes or a slight miss? I'm still not awake yet so I'm trying to factor out a few things here while I drink a cup o' Joe.

by 74MonteCarlo Mon May 09, 2011 12:32 pm

Rago wrote:How's it running? Anything noticeable like exhaust fumes or a slight miss? I'm still not awake yet so I'm trying to factor out a few things here while I drink a cup o' Joe.

Runs perfect.

by 74MonteCarlo Mon May 09, 2011 12:33 pm

JB2wheeler wrote:There is the little matter of alcohol content, the more there is, the worse your gas milage is. They claim the lower cost of the gas will make up for the lost milage. If you believe that, I have a nice bridge I will sell you real cheap. Why so cheap? It needs painting. JB

BAD gas mileage. I%20don%27t%20understand%20a%20single%20word%20you%20just%20said

"I don't understand a word you just said."

by lagunainnewark Mon May 09, 2011 1:25 pm

How much gas is in the tank? My Laguna seems to go for ever until it hits 3/8 of a tank, then it drops like a stone. Wire wound fuel senders aren't linear, full to 3/4 may not represent the same amount of fuel as 1/2 to 1/4. The best way is compare from a full tank and track the mileage. Good Luck, Ron

by 74MonteCarlo Mon May 09, 2011 1:33 pm

Last time I went to the gas station, I filled it to 7/8.

It dropped to 3/4(I think, I'll have to look again) after around 20 miles of driving.

What's stumping me the most, is it was NOT like this before the engine was torn down and detailed.

by The Dude Mon May 09, 2011 1:50 pm

OK, how about this.... No fumes, no leaks, no misses or surging. Correct?

You rebuilt the entire engine including new rings & bearings. Correct?

It's possible that the engine is still "tight" & just needs to break itself in before returning to your previous mileage. Expect to put anywhere between 1,000-1,500 miles on the car before it really starts to get back in it's groove. This is just a theory, but I've heard of it happening before.

by 74MonteCarlo Mon May 09, 2011 1:52 pm

Rago wrote:No fumes, no leaks, no misses or surging. Correct?

Correct.

Rago wrote:You rebuilt the entire engine including new rings & bearings. Correct?

Wrong. The motor was NOT rebuilt. JUST painted.

by The Dude Mon May 09, 2011 2:40 pm

Hmmm..... Letting them sit for a couple of weeks without gas can sometimes be enough to dry up the parts inside of a carburetor, but usually your float will start sticking first. At least that's what has happened to me in the past. I'd be more inclined to check your fuel lines for any wetness. Also get some starting fluid & spray around all of your vacuum lines/carb base/etc. while the engine is running & see if the idle changes at all while you are doing this. Might just have a minor vacuum leak causing the problem.

by ant7377 Mon May 09, 2011 4:24 pm

I still say its the gas. You wont see it in a newer car it can meter it self out. Dump some additive like a can of BG 44k in there and drive it .You might have gotten some fuel seperation from sitting for a while. You can get the stuff at the Chevy dealer or look up BG products on the web and find a distributor. Dosent hurt to use a can in your newer fuel injected car either. Its a good excuse to get out on the highway and clean it out a little too.

by 74MonteCarlo Mon May 09, 2011 7:57 pm

Been on the highway to clear it out. I use Sta-Bil every winter. I've put fresh gas in it twice since its been together. If sitting for the winter was the culprit, it would have happened the other three winters it's been in storage.

by ss2323ss Mon May 09, 2011 10:29 pm

Better start driving in the winter !! lol... Blended gas can bust loose gunk and cause problems.....

by 74MonteCarlo Mon May 09, 2011 10:36 pm

The day that car sees a winter is when I'm dead and it goes to the 3rd owner!

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