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  1. #1
    Newbie
    Join Date
    Dec 2010
    Location
    Northwest Indiana
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    9

    Default Poor Gas Mileage

    I have a 98 Chevy Suburban w/160,000. Has always ran great, gotten good gas mileage. Gas mileage began going down and then some engine codes come up and ended up replacing crank position sensor, timing chain and then cam position sensor. Truck runs good, however gas mileage still way down from what used to get. No codes come up and when putting it on a scanner, I am told that everything is working great. Wrote in about a week and a half ago, about hearing a hissing noise under hood, on top of engine where gas lines go into upper intake. Got response back to look at fuel pressure regulator. Worked on truck to get to this and when taking upper intake off, found some gasoline (very small amount) sitting on intake, between the fuel injector and the firewall. From fuel injector to the front of vehicle intake was dry. Replaced the regulator put all back together and still does same thing. Still has the hissing sound, seems to take long time to build up pressure and when cold, it will start and then if you shut off, wait a few seconds for put to build pressure and shut off, then restart it starts hard. Is loading up at that point. Any thoughts on what may be cause. If I open up again to expose fuel injector and plug in the injector and energize it, will this be a problem, or am I looking at replacing the fuel injector. Lot of thoughts going on here, any you may be able to help with I would really appreciate. Thank-you

  2. #2
    Newbie
    Join Date
    Dec 2010
    Location
    Northwest Indiana
    Posts
    9

    Default

    Worked on truck again and replaced the fuel injector. Found this to be the problem. Truck now builds pressure and holds it. No more hissing noise. Fuel pump shuts off almost immediately just as it used to.

  3. #3
    Legend
    murdog94's Avatar
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    Feb 2008
    Location
    Cloquet, Minnesota, United States
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    Default

    Glad you got it fixed.. did you find any physical malfunction with it for anyone in the future?? usually these are pretty reliable and for one to go out if you can see anything wrong for others to check would be great!
    Mike

    Currently

    1997 Chevy S-10 Blazer 4X4 with 330K miles and counting (Hunting rig).

    2009 Saturn Aura XE (wifes car)

    2011 F-150 Crew 4X4

    "Hold it to the floor till you see God.... Then Brake!!!!"

  4. #4
    Newbie
    Join Date
    Dec 2010
    Location
    Northwest Indiana
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    Default

    Ended up not being the problem as was thought. Could find nothing wrong with old injector. seemed to work better only a couple days. Gas mileage getting worse. Now being told that the computer may be the problem. At a complete loss now.

  5. #5
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    stephan's Avatar
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    Sep 2010
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    Far West, Oregon USA,
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    Default

    Quote Originally Posted by jac View Post
    Ended up not being the problem as was thought. Could find nothing wrong with old injector. seemed to work better only a couple days. Gas mileage getting worse. Now being told that the computer may be the problem. At a complete loss now.
    It seems that in the process of replacing the injector you accidently fixed something else that cured it for a couple days. Retrace your steps that you took in the repair & see if you can localize that would fit this scenario. X2 on Caddis post. What is your actual mileage? Bad gas mileage can be anywhere from 2 MPG to 12 MPG depending on the persons driving style, type of driving, weather etc.
    1988 Chevy C-3500 2wd (no pic)
    350 c.i. 5.7 L Stock Block, 4 Bolt Mains
    L-31 Vortec Heads, Edelbrock Cam & Intake,
    Holley 650, Flowtech Headers, Magnaflow exh.
    Jet Trans 700R4, B&M Ratchet, 4:10 gears,
    3" susp. lift kit "shadetree"
    No rev limiter, No speed limiter lol


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