Gas Mileage

u could try a tune up(spark plugs, distributor cap and rotor, plug wires and a fuel filter) For the fuel gauge it could be a problem with your sending unit. check the wiring just a few ideas for you

that is the 5.7 TBI, throttle body injection motor. On mine, I put a true dual exhaust system and gained about 3.5 MPG but if you do just a full magnaflow system with a high flow catalytic convertor you will get 3 MPG better, the truck had that on when i got it. Just make sure to baby the gas pedal, and yes, your gauge is the same as all of them, up to 96 they had the same gauges from 88-95. They do tend to jump around in those trucks. If you watch it closer, its more like 3rds of a tank, when u fill it to 3/4, 3/4 to 1/4, then 1/4 to empty. I have the exhaust system and a K and N air filter, which also helps. the cold air intake doesnt really make a difference, just get a K and N. I also have a 3" body lift and some other mods, and I get about 15 averaged between town and highway. Let me know what you get, what you do to the truck and how it helps. good luck. PS...o ya, and dont waste your money on a throttle body spacer, they dont work.

Thanks Tim for the info. I have about a 3" body lift with 33" Mud tires on it now, which don't help but I am looking for roughly 18" tire and wheel packages right now w/low profile to help that problem. As for the K and N air filter, and a TRUE dual exhaust, I am gonna probably just wait and have my parents get that for me for christmas or something. I am only 17, lol....so hopefully they help me out a bit.

my truck does the same with the gas gauge i have a 89 chevy with dual masterflow exhust lifted 4 inches with 33 ich yokohama tress

one of my buddys had a hypertech chip in his 5.7 L chevy and he got like 3 more mpg. if your truck is tbi you wont have a obd2 plug in and you will have to get a chip that replaces the stock one in your computer. i have a stock 1998 chevy z-71 and it gets about 13 crusin around.

Try a 4 inch muffler or a 6 inch to increase back flow pressure .I had a glass pack 4 inch on and was getting 17 PMG and replaced it with a surburban muffler now now getting 13.5 mpg . wnated to reduce the noise but also reduced gas mileage .

install 327 cu. inch heads on the motor

Put a throttle body spacer on my 305, and am getting over 10% fuel mileage. I also have my truck straightpiped, which right now is the best for my truck because i have a valvetrain problem, and backpressure makes my problem worse so i cut off my exhaust. It makes it loud and gives it a bit more power, but if you decide to do this, dont run your truck at high rpm because you don't want to have your valves float. I also have a k&n air filter and want to put a hole in my hood and make a shaker intake for my truck which will increase the cold air going into the engine. Also for better mileage put in 3.43:1 or 2something:1 ratio in the rear axle

install 327 heads or reduce muffler down to 4 inch dis or 6 inch

Got a 93. I have long tube hooker headers, 3 inch exhaust all through, no catz, new spark plugs,new plug wires, cold air intake, throttle bottle spacer, msd ignition box,jet performance chip, msd coil and I get abot 17mpg highway and 12 in city.....did i mention its on a 6 inch lift kit with 315 tires lol

run your tires close to max presure (caution bad in slipery weather) at speeds above 55mph leave your tail gate on and in the upright position with no box cover and drive with windows up. (reduces drag so mythbusters says) try to avoid use of a/c (it makes a difference) take it easy on the gas pedal. do a full tune up (use sinthetic oils they last longer and deal with tempature extreams better) use #1 gas. (higher octane the bigger the boom) OR spend a fair but of cash. cold air intake. headers and the rest of the exhaust. ignition upgrade. chip the engine. pollish the ports on the intake and the exhaust. lots of things you can do. good luck

i have an 98 k1500 z71 4x4 3 inch lift and 33s at the moment 35s soon it has the 4.3 liter i was wondering around what kinda gas mileage itll get my email is z71_4x4_countryboy@yahoo.com thanks for any info or tips

what kinda lift is that sespention or boddy message me with anwsor at ski.guy.1@hotmail.com

There are better manuals out there for a much cheaper price. Better compare prices and look for best quality. I got my manuals from www.carmanualstore.com - these manuals were the best and cheapest i found on the internet. And my customers are always happy with the results.

got a gmc sierra94 c2500 5.7ltr no 4whl odometer showin 319,643 but i the dash was jacked up for 2 years so im over under 400,000 on orginal everthing but you know alternator starter etc but motor and trans original took the motor out once to change core plugs one rotted out by the housin with all that i just rambled on about would it still be worth puttin throttle body spacers in or should i let it rest

replace the o2 sensors

i love all your trucks they all sound like mine and its pretty sweet to know im not the only one makin the older trucks get better mpg and grate performance still a toss up on should i do a throttle body spacer or not any thoughts? i got everything else :)

i have a 1998 chevy 4x4 5.7. k&n air filter tru duals with flo-pro 2 in 2 out turbo muffler new platinium plugs new wires and distib rotor and superchip programmer when programed in xs mileage mode i get about 20 mpg highway 15 16 in town and average about 16 mpg in performance mode this programmer also you to change many things shift points and pressures i beleive it helped my mpg more then anything its a flashpaq programmer made by superchips cost about 400.00 bucks.

-spark plugs (bosch) -ignitions flush (mr.lube $100) -made big difference on my vehicle, sucked gas like crazy before i had it done!!now perfect! -engine flush(or you can add fuel additives to your gas tank and oil tank *cheaper*) - k&n air filter ($60 approx)/ or air intake (possibly better tires/ wheel balance& alignment new gas gauge?? or get a mechanic to check it out for safety precaution)

I have a 97 chevy 1500 I have the same problem. Ill try some of what u guys said n see if it works

Throttle body spacers only work where the fuel is introduced before the intake manifold, not in true fuel injected vehicles. This means TBI, and carb setups benefit from them.

What wi9ll the extra gas mileage improvement cost? How much will you actually save and how long to recoup the cost of trinkets vs. doing nothing? The larger mud tires eat a lot of gas as they are not friction resistant tires. It's a truck, driven by a 17 year old with mud tires on it. It is not made for getting good mileage in these years. It is made to do truck work. Low gearing, for hauling and pulling power = low gas mileage. The best purchase is running shoes which are lighter then the lead boots you have now to show off or be the first away from the stop light. We've all been there, and some are still doing it at a price we accept.

I have a 95 Z71 with a 305 being a mechanic i had done all the above.i felt as tho my rpms were to high,then one day last week i couldnt put my truck in park. realized the shifter cable was streched and sure enough under the carpet the cable rusted and had streched. well all this time the truck was running betwwen gears. with the new cable my gas mileage has almost improved by double. wish i woulda found this a year or more ago. hope this helps some out there. Ron

overdrive is a wonderful thing aint it?

Mine has a 350 with a cold air intake, 33'' tires, 4x4, and i get about 18-20 cuz i got from plentywood montana to miles city montana on less than half a tank.

And itsa 93

i bought a 1991 chevy 2wd with a 350, i put a 3inch dual exhaust on it and 31 inch tires, workin on a 4 inch lift in the front and 3 in the back, can i get better mpg by putting higher or lower gears in the rear end?

tmoose, if you go with low gears, you gain low end torque, but give up mileage. Higher rear end with those tires you lose a lot of power and normally have to run in a lower gear causing low gas mileage. Your not going to get anywhere near 20 mpg no matter what you do.

i got a 95 5.7 tbi on 38s by 15.50s with a throttle body spacer complete msd set up tru dual and 318 gears and get roughly 16 mpg

21.4 MPG!!! yes. TRUE. How do I do it? a) I use tires with the lowest rolling resistance. b) Judiciously I check the TP every Saturday morning. c) When I start I just place my foot in the accelerator and try not to hit 2000 RPM d) When I take off, I let the truck roll initially and then I accelerate. e) I maintain my speed on the highway between 55 and 62 MPH using the Cruise Control f) If possible I avoid High Peak traffic. --When it idles, the gas mileage drops like a rock. h) I do not wait for normal suggested maintenance. --I'm a pilot to I try to prevent not to cure. o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o Try these habits and let me know how does it work for you. P.S. I live in TX so from time to time I drive at the posted speed limit. 85 mph in some areas, and I love the way my truck performs. Ha Ha

i have a 96 5.7 4x4 i have a K and N filter true dual exhaust a 5 inch lift a 4.11 gear ratio an eaton possi carrier and i get 18 miles a gallon in town 20 on highway drinks like an irishman when the wind is pushing back though

Stephen, do you have a bed cover or drop the gate to decrease wind resistance? Do you take your little old grandmother to church only on Sundays the way you drive? No, that's good habits to have to get better mileage. There may be a few after market products to add on, but the question is, "Spend $1,000 to save gas, and how much gas do I have to spend to break even?" Same as buying the hybrid cars for top dollar. You have to drive it 8 years to just start to get ahead. By that time it's worn out. The Prius car came out a long time ago, and got 40 mpg. Now several cars costing a lot less are getting that on gas and diesel. Keep up the good work.

I have a 1998 Silverado 1500 Z71 with the 5.7L. It's rated 12 in the city 16 highway. I put a k&n cold air intake, cat back exhaust, ECU chip, and new spark plugs. It cost a decent amount but I'm getting about 18 city 24 highway (on a good day of course). It's not that the engines get bad gas milage, it's the Gear ratios and 4wd system that kill the mpg.

I git 18 miles on high way with stock and 350000 miles plus some on it

Lol also its a short bed 1500 silvarodo 5.7 efi 1989

I use syn oils front to back. I put michelins best rolling resistance tires on (big investment), but I have 86K miles on then now. 3:58 or a 3:73 gear ratio will get better mileage than a 4:10 ratio. STAY off the gas pedal. - slow dow and roll to stop sign. Dont go from gas pedal to brake pedal. You want great gas mileage you have to strive for it. Taking it easy 2-3 times per tank full will not show you any better results. I check my mpg's every tank full and I use top grade 92 octane.(NO ethonal). And I use Sea Foam every tank. I average 20 mpg. (1997 5.7). 190K miles on it. Has not had a tune-up .

I have a 92 4WD Suburban with 133,000 miles - bought new... Recently mpg dropped to about 12 mpg on highway. I replaced just about every sensor- no change... Then I put on a new Bosche O2 sensor - $16 - and mpg went up to over 16.5 at over 70mph on highway... Who woulda thunk...

Scrap the tbi engine. Or swap heads, or heads, intake and switch to a carb. I have a 94 2wd 305 was 4L60e and 3.08 gear, I run 29" highway tires at max press, it has the front air dam and has been lowered 2" and had the spare removed, the truck weighs 4200lbs, i've tried the throttle body spacer, the "ultimate tbi mod", deleted the a/c system, all sensors replaced, the salad bowl mod, installed headers with 3" collectors that Y into a 4" then into a flowmaster 40 modified for 4", set base timing at 14*(did get a bit more power), tried a chip, the K&N filter and nothing ever changed still got 12mpg, I even changed to a 3.73 gear (expecting to get worse mileage as a trade off for better acceleration) but it didn't change a bit, then went on to supercharge it with 7psi boost and guess what no change lol still the same 12mpg, the truck had very regular maintenance got new plugs cap and rotor etc. Yearly. in the end the thing was slow and got terrible gas mileage and eventually the supercharger pushed a head gasket out of the 250k motor Then in went a bone stock never opened (only the carb has ever been off only to clean it) 86 caprice 305 with 400k with 15w40 oil (was pulled from family car before it went to scrap but likely could get one for about $200) and a nv3500 ($200) now it gets good gas mileage (18-20mpg and I drive the piss out of it) and it pulls way better than the tbi did, can squawk tires in 3rd gear (power is about half way between the NA tbi and the 7psi boost tbi) this is because of a better head design in the older carb engines, I also found that the best fuel mileage was at 2000-2500rpm with as high of vacuum you can get to sustain that rpm (mine is roughly 17in/hg w/s 400k motor) so plan your gear ratio/ tire set up for what ever speed you will be doing, mine (3.73 w/29" tires) works well for 60mph (2000rpm) to 75mph (2500rpm) if you do go for heads and don't wanna spend a lot on aftermarket go with the 327 heads (they will increase compression ratio which will lower the rpm at which it makes best fuel economy) or if you want fuel economy not power 305 heads and run your set up as is, dad did that to his 89 350 wt 4wd turbo400 3.08 gear and would get about 22mpg and had a lot of pull down bellow 2500rpm but it wouldn't do anything above 4500rpm and would start to slow at 4000rpm (this is with only changing to 305 tbi heads, otherwise the truck was completely stock, no chip/ refund just heads) If you want economy and power and plan on keeping it around for a while, ls swap it. 4.8s make better power than the tbi 454s and get 19mpg in a 5800lbs 2010 truck (should get between 22-25mpg in an 88-98) engines w/harness and computer can go for about $400-500 but it'll take time and research to do the swap plus adapted for and such can add an extra $100 As for the gauge it sounds like a sending unit (mine had a burned section at 1/4 and when it got there the needle would bounce all around, replaced the sending unit and now it has no issues) and if you do decide to ls swap it it's a good time to swap the fuel pump too.

i have a 97 and the vortec box on the intake, i took that off and covered it. i used the butt of a pop can and a hose clamp. that gave me about 2 mpg and some torque. and if you do the muffler delete or a full true dual exhaust to make as less back pressure as possible with increas hp by 5 and mpg by 1 to 3 depending on 1/2 ton or 3/4 ton.

You cannot "reset" your gauge. This is a common issue in GM and indicates that your fuel pump will need replacing soon. I've seen it go years and I've seen it go days. Better to replace asap so you don't end up stranded.

I have a 99 Tahoe 5.7l K&N intake with a Gibson 3 inch cat back. I am only getting 10 mpg on average in town with the best being 15 on the highway in Montana. I have done the plugs and wires, gas filter and pump. and I am running 275/65 17 tires. I cleaned the injectors but I did not replace the spider. I have great pressure and amazing throttle response with 180k on the engine. Is it time to replace/rebuild it or am i missing something that is killing my mpg?

For your fuel gauge, if it moves around while driving or hitting bumps, it's probably the sending unit on your pump. However the most common problem is the gauge itself. They wear out and start randomly changing position. I have a 98 Silverado and the gauge will sometimes read 1/2 when I know I have closer to 3/4. Then 5 minutes later it's reading empty, then 3/4. That's the sign that it's the gauge. About $35 off Amazon and not hard to replace. Lots of good videos on youtube. Better than replacing your fuel pump and finding the problem still there

88 Chevy K1500; 100,000 miles. Can I use 225 60R 16 safely? Specs say 75R