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Fuel mileage expectation 305

Discussion in 'Chevy Trucks' started by Grshppr, Mar 9, 2003.

  1. Grshppr

    Grshppr Senior Member
    Messages: 268

    I bought a 1990 Chev 1500 4X4 ext cab s/b truck. It has the 305 fuel injected motor in it. The truck has a 3spd auto, and a 3:73 rear. I was just wondering what kind of mileage I should be able to get with it. I am currently getting 12mpg city driving. I thought this was a bit low, so I was wondering what some of you guys were getting for fuel economy, and if you had any tips on how to increase it. ( I replaced the O2 sensor, cap/rotor/fuel filter and air filter when I bought it). Thanks
  2. myo

    myo Senior Member
    Messages: 193

    I had a Chevy 1500 4x4 Reg cab 305 and got 10-11 in city and 14-15 on highway
  3. wyldman

    wyldman Member
    Messages: 3,265

    That's about average for that truck.Sounds like you've done the most common stuff.The mileage should improve some as the weather starts to warm up.
  4. Grshppr

    Grshppr Senior Member
    Messages: 268

    Actually I figured it out wrong, its getting 10 mpg. You are right, it'll probably get better as the temp gets warmer outside. I was just surprised, because my dad has a 350 in an 89 with 4:10 gearing and 3 spd standard and gets 12-14 mpg. I figured the 305 would be better than that or at least the same. Oh well, once this one dies I'll drop a 350 in. Looks like it would be a simple swap.
  5. snowflake

    snowflake Member
    Messages: 86

    yuppper 10 mpg is about alll you are goin to get:D everbody that i know thats has one is gettin about that too most of them say it is gutless too. cat back duel exhaust and k&n air filter mite help mileage . otherthan that like you say a 350 mite be better. mite have to change the puter and injectors too.
    butt >>>wyldeman<<< willl be able to tell you if you have to fer sure.
  6. wolfie

    wolfie Senior Member
    Messages: 174

    My dad had a 98 with the 305 and got 14-15 mpg most of the time... I took it on a trip a few years ago and I got 18-20 mpg with it... 10-12 sounds real low to me... On my 89 2500 with a 350 I got 11-13 and I could get 10 with the plow on.
  7. dillyolboy

    dillyolboy Member
    Messages: 97

    I agree with wolfie. We have a 95 that got around 15 in town also 3.73s. At 110k the motor burnt up. Apparently that is a common problem with 305s. At around 100k they start burning oil real fast cause the intake manifold gasket starts leaking. I talked to a guy that works at a garage and he replaced 16 during one summer all for that problem. Now that 95 has a 350.
  8. wyldman

    wyldman Member
    Messages: 3,265

    The newer trucks do slightly better on fuel.He also has the 3 spd auto,no OD,so that will hurt it some as well.
  9. Grshppr

    Grshppr Senior Member
    Messages: 268

    I'm gonna check the ignition timing one of these days. Its the only thing left that could give me a bit better mileage. Otherswise if it doesn't increase much I'll be looking for a fuel injected 350 so that way if I'm gonna get 10-12 mpg at least I have power.:)