mrblunt Posted March 22, 2004 Report Share Posted March 22, 2004 I grew up in a time of fuel injection so sorry for the nub question. So i have this beater, 88 sentra, 1.6L 4cyl and its carb'd. I bought it from a guy on here and its been incredibly dependable. For 500 i can't beat the deal. So anyways it takes about 12gal to fill the tank up and i'm getting about 200 miles to the full tank. I recently did a full tuneup. Plugs, wires, distributor cap, whatever is inside the cap that creates the spark(having a brain lapse), fuel filter, air filter, pcv, oil, flush and fill and t-stat. So i expected the fuel efficency to increase w/ all the new junk added. WRONG. still good old 200 miles to a tank. This is w/ 30-40 highway miles a day to and from work and light city driving. It is a 3 spd auto. I now think the carb may need a cleaning but i've never torn into one. Any tricks or helpful hints i should be aware of before i tear into this thing. I'm not a nub, i built the engine in my eclipse, twice(dont ask). Thanks in advance. Quote Link to comment Share on other sites More sharing options...
mrblunt Posted March 22, 2004 Author Report Share Posted March 22, 2004 o, btw. i've checked numberous places online and it is reported to get an average mpg of 36. this is the reason for my question, i'm no ways near it. or maybe i dont' know how to properly figure out fuel economy smile.gif Quote Link to comment Share on other sites More sharing options...
nurkvinny Posted March 22, 2004 Report Share Posted March 22, 2004 Some of the following may be obvious, but here goes. If you're getting shitty mileage, here's a couple things to try / check: - Vacuum lines. Take a minute and check (or replace if they're the original) the lines. - Catalytic converter. Can kill MPG. Usually, you'd notice a foul smell if it was going bad, but if you know a shop that will make you a 'test pipe', it usually helps. - Before you tear the carb apart, try a good can of fuel additive w/ clearner. - Tires / alignment. Low tires and/or being out of alignment can both hurt MPG. Quote Link to comment Share on other sites More sharing options...
ridenred27 Posted March 22, 2004 Report Share Posted March 22, 2004 before you tear into the carb go to napa and pick up a pint/quart of lucas fuel treatment this stuff works very well in gas and diesels cleans the carbon and helps with dispersing water. Quote Link to comment Share on other sites More sharing options...
slow4now Posted March 22, 2004 Report Share Posted March 22, 2004 I actually recommend Chevron Techron fuel additive, it's the only stuff that I've found to actually work (though I've never tried the Lucas additive). Quote Link to comment Share on other sites More sharing options...
mrblunt Posted March 23, 2004 Author Report Share Posted March 23, 2004 funny you should mention the cat. i have so may leaks in the exhaust i'm not sure the gas is even reaching it. When i start the car up on a cold day you can see right under the engine the exhaust is shooting out. Its got about 5 leaks and is rather loud. i case less, its a beater. Tires and alignment are cool, no worries there. Now w/ the vac lines is this something that really hurts a carb or will a vac leak on fuel injection do the same thing. I really need to do some research on carboration, i know squat about it. looks like a throttle body that dumps fuel into it and the engine sucks in the fuel and air in threw the tb flaps. i'll surely try the fuel cleaner, where can the chevron techron additive be found. i'll try the lucas as well, couldn't hurt. i probably wont be driving the car to much but if the gas stays at 1.90 to 2.05 a gallon i may need to. fn oil companies. thanks for the help btw, i normally research things first but i was at work and time was limited, i'm a lazy bastard Quote Link to comment Share on other sites More sharing options...
Dave1647545494 Posted March 23, 2004 Report Share Posted March 23, 2004 if the car has high miles the carb is due for a rebuild. get a good dealer service manual if you decide to attempt it. its easier to assemble an engine than to rebuild an emissons spec carb and have it work right. check for vacum leaks everywhere they can make you go way rich. good places to check are the base gasket and all thee vacum hoses. if you decide you need to rebuild the carb and don't want to mess with it you can buy a rebuilt carb from the auto parts store or get a kit and I can rebuild it for you. Quote Link to comment Share on other sites More sharing options...
ridenred27 Posted March 24, 2004 Report Share Posted March 24, 2004 now your exaust can play a big part on gas milage those carbs are tuned to that restictive exaust. ive seen where and read where increasing exaust diameter can have a neg effect on the milage.(bad exaust same thing) i am assuming that this is a feed back carb (computer carb) and you have a leak before the o2 sensor that will cause the computer to enrich the fuel mixture. as far as the lucas additive ive used it in my frieghtliner at every fill up and got almost 1.5mpg increase which is alot for a big truck. my mother uses it at every oil change and she has seen noticable increase in mpg since she started. she drives around 130 miles a day. but cheveron additive works well too ive used them both with good results. hope this helps Quote Link to comment Share on other sites More sharing options...
Guest jpurdy2003 Posted March 25, 2004 Report Share Posted March 25, 2004 Ahh...memories. My first car was a 1986 Sentra (different body, mechanically identical) If I could give you any advice, as a guy whose family has owned three cars mechanically identical to yours, I would most deinitely say let sleeping dogs lie. I don't care how mechanically experienced you are, these emissions-spec carbs should be left alone if it idles, accelerates, and isn't spewing fuel. This is a rebuild for only the most experienced and meticulous builder. Just be happy it works, unless you know someone who has successfully tamed one of these things. Quote Link to comment Share on other sites More sharing options...
Sully Posted March 29, 2004 Report Share Posted March 29, 2004 You should definitely get the exhaust replaced. With that many leaks, it will hurt your gas mileage, cause poor performance and decrease your power. Quote Link to comment Share on other sites More sharing options...
mrblunt Posted March 31, 2004 Author Report Share Posted March 31, 2004 i'm nearly 1/2 tank past adding the lucas and so far nothing is improving gas milage wise. this thing is like clockwork, i get exactly 50 miles per quarter tank. no matter what speed i drive on the highway, what octane i use. i need to get under the car and see how many leaks i have in the exhaust. if the cat is gumbed up i'll probably just gut it or make a handy test pipe. the exhaust is loud, i really should replace it. I just cant see spending 200+ bucks on an exhaust for the thing when i only spend 500 on the car itself. lol Quote Link to comment Share on other sites More sharing options...
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