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Bad gas mileage 92 K1500

This is a discussion on Bad gas mileage 92 K1500 within the Technical / Maintenance forums, part of the General Discussion category; I've got a 92 RCLB K1500 with about 110k miles. It has a new fuel pump and filter, new AC ...

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    Bad gas mileage 92 K1500


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    I've got a 92 RCLB K1500 with about 110k miles. It has a new fuel pump and filter, new AC Delco 02 sensor and CTS, recent cap, rotor and plugs, new air filter and timing has been set. I have run sea foam through it and used it in the tank as well. It has a rebuilt 700r4 and has 342 gears with p265 tires. Highway cruise RPM is about 1700 at 60 MPH, Compression is good on all 8 cylinders, it idles smooth and starts flawlessly. I have only been getting about 10 MPG with it and I drive mostly highway. From what I understand some of you guys are getting into the 20's with these trucks. Has anybody got any thoughts on what else to look at?

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    2000 Chevy 2500HD 6.0L
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    Re: Bad gas mileage 92 K1500

    I have never seen 20's. 16-18 tops and I have the 5.0L in my 91 K1500 SB with 3.42 gears. I am running the stock 235s and larger tires are hell on MPG but I would think you could still get over 15 but you need to be gentle on the throttle.
    Last edited by terryk; 02-03-2009 at 09:29 AM.

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    Re: Bad gas mileage 92 K1500

    ive never seen over 12 with my 88. With my 95 I get around 15-16. Did you properly gap your spark plugs? How strong is your spark?
    88 K1500 5.7 220K SOLD
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    Re: Bad gas mileage 92 K1500

    Quote Originally Posted by StingRay92
    I've got a 92 RCLB K1500 with about 110k miles. It has a new fuel pump and filter, new AC Delco 02 sensor and CTS, recent cap, rotor and plugs, new air filter and timing has been set. I have run sea foam through it and used it in the tank as well. It has a rebuilt 700r4 and has 342 gears with p265 tires. Highway cruise RPM is about 1700 at 60 MPH, Compression is good on all 8 cylinders, it idles smooth and starts flawlessly. I have only been getting about 10 MPG with it and I drive mostly highway. From what I understand some of you guys are getting into the 20's with these trucks. Has anybody got any thoughts on what else to look at?
    Is your TCC locking up? Those RPMs imply it is but have you checked it?

  5. #5
    Al_97GMC
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    Re: Bad gas mileage 92 K1500

    no ones getting into the 20's with a 92 k1500

    dont get over 2k on acceleration


    do you take a lot short trips as well because its cold as chit there and the truck might not even get out of open loop
    Last edited by Al_97GMC; 02-03-2009 at 09:55 AM.

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    Re: Bad gas mileage 92 K1500

    TQ locks up fine and the truck leaves from a heated garage every morning to a full 15 min highway trip to work in the morning. I can't remember what I gapped the plugs to but it would have been spec. My old 72 GMC with a 373 rear end got me 10 mpg on a bad day. In good tune I could muster about 14 and it had a qjet. It would cruise 6o MPH at well over 3 grand. TBI in closed loop with a 700r4 should do better than that. My brother has the same truck and has pulled down much better than 10.
    Last edited by StingRay92; 02-03-2009 at 10:28 AM.

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    Re: Bad gas mileage 92 K1500

    Try .045 gap...it helped my 94 a lil' but, managing about 17 to 18 on the highway...15 thru town.

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    Re: Bad gas mileage 92 K1500

    Quote Originally Posted by StingRay92
    TQ locks up fine and the truck leaves from a heated garage every morning to a full 15 min highway trip to work in the morning. I can't remember what I gapped the plugs to but it would have been spec. My old 72 GMC with a 373 rear end got me 10 mpg on a bad day. In good tune I could muster about 14 and it had a qjet. It would cruise 6o MPH at well over 3 grand. TBI in closed loop with a 700r4 should do better than that. My brother has the same truck and has pulled down much better than 10.
    Given everything you have checked you should be able to get at least 15+. Not sure what else to check really.

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    D to the MAX gr8shot's Avatar
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    Re: Bad gas mileage 92 K1500

    Coil could be getting weak... idk thats just a guess. Does your truck get to normal operating temp? Should get to about 190 or something like that. If it's not warming up enough then yeah, it'll stay in open loop, and you'll get nasty mileage.

    Another thing that killed my mileage was a brake caliper dragging. Jack up the front of your truck and give the tires a spin. If it doesn't make it a whole revolution at least, then you probably have one sticking. You can clean it up, and grease it up, or just buy and install a new one, they're cheap. I discovered one on my truck and gained 2mpg after replacing it. Your rear brakes could be out of adjustment and dragging too. If the drums don't come off without prying and banging on them, then they're definently dragging.

    On a side note, you definently should be getting better than that. On the 92 in my sig that has 3.73's, I can knock down 16 if I go 60mph. Heck I get 13 pulling my band's little 6x10 trailer going 60 on the highway, so you should be doing way better.
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    Al_97GMC
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    Re: Bad gas mileage 92 K1500

    hell ive got a 97 v6 rcsb 2wd and best ive seen is ...

    100% city hammering on it some i get around 12

    normal city 14-15

    mixed 17-18

    all highway 19-20
    Last edited by Al_97GMC; 02-03-2009 at 02:25 PM.

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    Re: Bad gas mileage 92 K1500

    My 95 doesn't like the ethanol fuel (E-10) much.
    1996 Yukon. Stock on 285's

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    Al_97GMC
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    Re: Bad gas mileage 92 K1500

    Quote Originally Posted by WalterMitty
    My 95 doesn't like the ethanol fuel (E-10) much.
    yes avoid at all costs
    Last edited by Al_97GMC; 02-03-2009 at 02:33 PM.

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    Re: Bad gas mileage 92 K1500

    Im getting 16-18 City and 20 plus highway, but thats with a tbi v6 and plus babying it. My K5 last time I drove it got 8-9 but I was one the gas alot.

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    Re: Bad gas mileage 92 K1500

    My 91 gets 11mpg in the winter (8mpg with the lights on), and 16mpg (14mpg with the lights on) in the summer.

    -1953 3100- -1991 K1500- -1999 Ford Ranger-

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    Re: Bad gas mileage 92 K1500

    Its the time of the year mine is bad too but in the summer ill do 18 on the highway with 13 city if i baby it (less than 2k on acceleration)
    1994 ECSB K1500 F44 Z71, 295/75/16 tires.

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    Re: Bad gas mileage 92 K1500

    Quote Originally Posted by PHATSPEED7x
    My 91 gets 11mpg in the winter (8mpg with the lights on), and 16mpg (14mpg with the lights on) in the summer.
    just curious how in the world did you figure that out? And why does it get worse with them on?
    1994 ECSB K1500 F44 Z71, 295/75/16 tires.

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    Re: Bad gas mileage 92 K1500

    Quote Originally Posted by dsponder
    just curious how in the world did you figure that out? And why does it get worse with them on?
    Electrical demand for the lights takes away from power to coil, resulting in less spark, poor combustion, and worse economy...


    -1953 3100- -1991 K1500- -1999 Ford Ranger-

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    Re: Bad gas mileage 92 K1500

    most of the guys getting higher milage have upgraded things like the intake, exhaust, and the ECM/PCM programming.

    i squeezed 20 mixed out of my 92 C1500 with a 5.7, CAI, full exhaust, and plugs gapped at .055" for a couple tanks last spring.
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    Supporting Gold Member GreaseDog's Avatar
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    Re: Bad gas mileage 92 K1500

    Quote Originally Posted by PHATSPEED7x
    Electrical demand for the lights takes away from power to coil, resulting in less spark, poor combustion, and worse economy...

    you're partially right. the electrical draw on the battery, and the alternator tries to keep up with it, which makes it harder to spin which eats up power.

    or it could be the fact that the truck is ashamed to look like that, and if it gets crappy economy you'll drive it less.
    Last edited by GreaseDog; 02-03-2009 at 03:34 PM.
    77 Chevy K20 - 80 GMC K2500 (in pieces)
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    D to the MAX gr8shot's Avatar
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    Re: Bad gas mileage 92 K1500

    04 Chevy LB7 Dmax. Some go fast goodies from Husker Diesel

    SOLD!!!! 07.5 Chevy LMM Dmax DPF Deleted, EFI Live from Husker Diesel & more 448hp/834tq

    1992 Chevy 1500 ECSB 4x4 350TBI 320k miles

    '95 Chevy 2500 ECLB swapped in a 95 12v cummins, NV4500, 2wd

 

 
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