Automotive Forums .com - the leading automotive community online! Automotive Forums .com - the leading automotive community online!
Automotive Forums .com - the leading automotive community online! 
-
Latest | 0 Rplys
Go Back   Automotive Forums .com Car Chat > Engineering/Technical
Engineering/Technical Ask technical questions about cars. Do you know how a car engine works?
Reply Show Printable Version Show Printable Version | Email this Page Email this Page | Subscription Subscribe to this Thread
 
Thread Tools Search this Thread
Old 05-19-2009, 01:22 AM   #1
Jayp03
AF Newbie
 
Join Date: Apr 2009
Location: Kodiak, Alaska
Posts: 14
Thanks: 0
Thanked 0 Times in 0 Posts
excessive gas usage?

i have a 95 Chevrolet silverado...which is a 20-30 MPG truck and it loses gas like nothing...a full tank of gas would only last for about half a week... i only drive the truck to school which takes 5 mins to get there from my house and another 5 min to get back home...and already a quarter tank of gas would be gone! i dnt noe what can be causing this but i need help... so pls help me!
Jayp03 is offline   Reply With Quote
Old 05-19-2009, 07:22 PM   #2
curtis73
Professional Ninja Killer
 
curtis73's Avatar
 
Join Date: Nov 2002
Location: Penn Hills, Pennsylvania
Posts: 3,558
Thanks: 0
Thanked 9 Times in 9 Posts
Re: excessive gas usage?

Uh... 20-30? I don't think so. Best I could get from mine was 14 on the highway with a VERY light foot.

One of your problems is the short commute. Its not getting up to temperature which uses more fuel. Its also probably not highway which means stop and go, which uses more fuel.

Do an actual MPG check. Fill the tank, note the mileage, run it until its almost empty and see how many gallons it takes to fill it. Miles driven divided by gallons = MPG. Anything better than 10 mpg would be normal, but you could hope for 12-14 at best.
__________________
Dragging people kicking and screaming into the enlightenment.
curtis73 is offline   Reply With Quote
Old 05-31-2009, 03:21 AM   #3
Jayp03
AF Newbie
Thread starter
 
Join Date: Apr 2009
Location: Kodiak, Alaska
Posts: 14
Thanks: 0
Thanked 0 Times in 0 Posts
Re: excessive gas usage?

starting mileage bfore i refilled the tank was 113,092 and about empty was 113,261 which i subtracted by 113,092 to get 169 driven...and divided that by Gallons 20.138 which gives me 8.39209455...so MPG=8.39!!! sux!! not normal at all so what can be causing this?
Jayp03 is offline   Reply With Quote
Old 05-31-2009, 10:06 AM   #4
HeavyJ
AF Regular
 
Join Date: Nov 2005
Location: None
Posts: 110
Thanks: 0
Thanked 0 Times in 0 Posts
Re: excessive gas usage?

What engine/trans do you have? Done a thorough tune-up? Oversize tires? You said you drove it only to school, some of the guys I went to school with loved to siphon gas instead of buying their own.
HeavyJ is offline   Reply With Quote
Old 05-31-2009, 10:17 AM   #5
shorod
SHO Off
 
shorod's Avatar
 
Join Date: Jun 2004
Location: Cedar Rapids, Iowa
Posts: 10,628
Thanks: 67
Thanked 279 Times in 272 Posts
Re: excessive gas usage?

And is it 4WD? How long have you had this truck, and were you ever seeing better than 8.4 mpg in similar driving and weather? When's the last time it had a tune up, including the air filter?

If 4WD (which would seem common in Alaska) I'm not too sure your fuel economy is that far off what you should expect.

-Rod
shorod is offline   Reply With Quote
Old 05-31-2009, 10:23 AM   #6
curtis73
Professional Ninja Killer
 
curtis73's Avatar
 
Join Date: Nov 2002
Location: Penn Hills, Pennsylvania
Posts: 3,558
Thanks: 0
Thanked 9 Times in 9 Posts
Re: excessive gas usage?

My 88 2500 (same TBI engine as you have) got about 10 in around town driving, so your 8.39 isn't far off the mark for your short commute, but you're right its a little lower than you could be getting.

What tire type and size are you using. Many people make the mistake of going with good looking 31" tires that are wide and knobby, then wonder why they lost 3 mpg. If you're using this for commuting, 235/75-16 is far more tire than you'll ever need.

Is your truck 4x4? The extra rotating weight of the front hubs/axles and the transfer case will hurt mileage a bit. With 113k on the clock, I would suspect you also have some leakage of the fuel nozzles. Its a common issue with TBIs. Since you're in a colder climate, you are probably also crippled by gasoline that has up to 20% ethanol in it. Down here its our "winter blended" gasoline, but colder climates (or places that have regulated different fuels for emissions reasons) sometimes get ethanol in their fuel year-round. Ethanol contains some of its own oxygen. The O2 sensor reads this as a lean condition and injects more fuel to compensate. The result is worse MPG. To compound the situation, Ethanol contains less energy which lowers the power production of the engine. That causes you to use more "foot" to maintain the same driving style and further makes mileage worse.

You can check the obvious things; spark plugs and wires, O2 sensor, catalyst restriction, and coolant temp sensor, but its hard to determine if they're failing. But, you'll be spending large amounts of money to replace those things, and honestly the best you could hope for is about 10 mpg at best. My 98 F150 with the small 4.6L V8 only gets 11-12 if I use it around town, and that is an overhead cam multi-port EFI with high compression using 100% gasoline without ethanol.

You're trying to move 5500 lbs of brick-shaped truck through the air with heavy tires and wheels with a large engine that has low compression and a TBI system that injects liquid fuel spray at low pressure. You're further crippling it with those short trips where it never gets up to temp. The TBI trucks were never good examples of efficiency. Take it out on the highway (which isn't easy in Kodiak) but try running a tank through it with sustained highway speeds and I think you'll see a huge improvement.

My honest suggestion is to trade it for a 96-99 Vortec truck. That is an instant 5 mpg jump, plus you'll get tons more torque and HP.
__________________
Dragging people kicking and screaming into the enlightenment.
curtis73 is offline   Reply With Quote
 
Reply

POST REPLY TO THIS THREAD


Bookmarks
Go Back   Automotive Forums .com Car Chat > Engineering/Technical

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -5. The time now is 08:32 PM.

Community Participation Guidelines | How to use your User Control Panel

Powered by: vBulletin | Copyright Jelsoft Enterprises Ltd.
 
 
no new posts