how to improve fuel milage on a chevy 350 tbi? help!

Discussion in 'Gasoline Engines' started by 93f250idi, Feb 13, 2011.

  1. 93f250idi

    93f250idi strokin

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    i recently picked up a 92 gmc sierra. it has a 3" body lift and 33s. i drive it every day an im getting about 10 mpg :puke:. truck has 267k miles :eek: has a new tranny with shift kit and a new jasper rear end. im looking for some cheap fuel milage. im gonna try and do a tune up pretty soon and change the oil and fuel filter but other than that what else can i do? i need some help as this thing is killing me! thanks!
     
  2. jonathan

    jonathan Full Access Member

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    i used to have a 95 z71 and it would get 19 mpg on the highway and 13 in the city. keep it out of od under 55 that helps with city mpg. a tb spacer let me gain 2 mpg. i put a edlebrook intake on it it didnt do anything for mpg just more nuts. jet makes a chip that claims to inporve mpg. hope this helps. btw mine had 285000 miles on it they last forever lol
     
  3. 93f250idi

    93f250idi strokin

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    how much does a tb spacer cost?
     
  4. jonathan

    jonathan Full Access Member

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    70 or 80 thourgh jegs or summit get the store brand one they are cheaper. i miss my old z71.
     
  5. 93f250idi

    93f250idi strokin

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    well if mine doesnt pick up in milage it will be for sale LOL. i really like the truck but i just cant afford to drive the darn thing. $4000 obo
     
  6. jonathan

    jonathan Full Access Member

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    is it 4x4 is it a extend cab how are the cab corners
     
  7. jonathan

    jonathan Full Access Member

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    you should get a dodge v10 they only get 6 mpg in the city and 11 on the highway it sucks lol
     
  8. sle2115

    sle2115 NRA LIFE MEMBER Staff Member

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    TBI spacer will help, also, check the snorkel. If it is the one that runs to the passenger side fender and has an "airbox" type canister on the end right next to the filter, look at Jeg's or Summit for a replacement unit. They have like a sleeve that takes the place of that can. Take the can off and look into it...looks like about a 2" hole, VERY restrictive. On my 94 I replaced it and put a spacer on it, and it made quite a bit of difference. Opens up the airflow and cools the intake charge. Not only will fuel mileage improve, but it made mine run much better. Yours may or may not have that canister, but it's worth a look and I think the kit was $15 or so.
     
  9. 93f250idi

    93f250idi strokin

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    its a reg cab short bed. one cab corner is good and one needs replaced but the hole isnt too big. it also needs one body mount fixed, but if your interested in it i will fix the cab corner and body mount. its a pretty nice truck overall. and thanks sle2115
     
  10. 93f250idi

    93f250idi strokin

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    and yes its a 4x4.
     
  11. jonathan

    jonathan Full Access Member

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    i was woundering what those go for around here.thanks now i know. just got a new idi so i dont need it
     
  12. 93f250idi

    93f250idi strokin

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    i want pics! ive gotta soft spot for idi's. :D
     
  13. 93f250idi

    93f250idi strokin

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    anyone else??
     
  14. opusd2

    opusd2 Full Access Member

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    I'll toss in my 3 cents worth.

    I have an 89 GMC K1500 4x4. It has the 350 with 700R4 in it, with decent all terrain tires that offer excellent mileage, but which don't howl when I fly down the highway. No lift kit, and a fiberglass cap on the back. I can get just about 21 mpg if I watch myself and am not hauling anything too heavy. On a bad day I get 15.

    Here's what I did:

    First modification after buying the truck 17 years ago was to tighten up the front end. Remove the slop with new ball joints, tie rods/ends, new gas shocks all around with coil overs in the back. All of this reduces movement of the body and the need to correct steering, all of which requires a little more effort on the part of the engine.

    Then I milled myself a spacer for under the TBI, I used aluminum but anything that is gas resistant like plastic will work just fine. In fact, on my old 73 F100 Highboy with a 360 engine benefited with just a smaller one. But anyway, back to the GMC. I added a hotter coil, 8.5 mm plug wires and a new ESC module along with a quality cap and rotor with brass terminals ( I always went with Blue Streak Standard until the quality dropped). Then replace the spark plugs with quality ones, like AC Delco or NGK. With a hotter coil you can open the gap a little bit more.

    And after I installed a cooler T-Stat along with a Jet Thermo Power chip, I felt an increase in power, and it also helped mileage. As for the silencer tube, well, the inside can be opened up to act better but look stock. Then I went with a K&N filter for air and oil, and synthetic fluids all over the vehicle.

    I have a few more secrets that I just can't get into, but I will say that the truck will pass any emissions test as no equipment is missing.

    Good luck
     

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