1992 Deville bad gas mileage
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  • 2 Post By basscatt
Cadillac DeVille 1985 to 2005 including:
1985-1992 Fleetwood, 1993 Sixty Special, All FWD Forum Discussion, 1992 Deville bad gas mileage in Past Cadillac Vehicle Discussion; I have a 1992 cadillac deville with 80k miles, back in june i did a trip to wisconsin from colorado ...
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    Cadillacdevilled is offline Cadillac Owners Member
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    1992 Deville bad gas mileage

    I have a 1992 cadillac deville with 80k miles, back in june i did a trip to wisconsin from colorado and got 28mpg at 65-67 mpg 3 weeks ago i did the same trip from wisconsin to colorado and back to wisconsin and got 18-20mpg at all speeds and now this week getting at 17mpg at highway speeds.. no engine lights or codes and car runs great so what should i check into?

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    MoistCabbage's Avatar
    MoistCabbage is online now Cadillac Owners 10000+ Posts
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    Check the Fuel Pressure Regulator. It's located on the fuel rail, and has a vacuum line running to it from the TB (another member may post a picture). Disconnect the vacuum line from it with the engine idling. Any sign of fuel indicates a ruptured diaphragm --- bad FPR.

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    cadillac_al is offline Cadillac Owners Connoisseur
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    Re: 1992 cadillac deville bad gas mileage

    Winter fuel is known to lower mileage too. If any sensors are bad enough they should generate a code so I would wait for that.

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    dennis93coupe's Avatar
    dennis93coupe is offline Cadillac Owners Connoisseur
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    Re: 1992 Deville bad gas mileage

    As far as the bad mileage, you can have a minor thing such as a bad thermostat and have a drop in mpg. No codes? You need to find a FSM and learn how to use it, learn how to do diagnostics such as checking parameters which can all be brought up on your onboard diagnostics. You don't need a scanner for your car, everything is built in. Back to the fuel pressure regulator, as Ranger mentioned here is a picture.


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    calvin ar is offline Cadillac Owners Fanatic
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    Re: 1992 Deville bad gas mileage

    when my injectors went similar thing happened like that but would find out if fuel presser is right first and the fuel regulator is only 1 part of that system you have to check presser at shrader valve. also cloged fuel filter will do this some times if there is rust on out side replace as a general rule (show amount of time it has been in car)

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    bessy2013 is offline Cadillac Owners Member
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    Re: 1992 Deville bad gas mileage

    02 Filter in mine was bad. Replaced it, gained 4mpg highway and town. Course that a mechanic's job because of it needing to be lifted to get at

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    MoistCabbage's Avatar
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    Quote Originally Posted by dennis93coupe
    as Ranger mentioned here is a picture.
    That's the second time I've been confused with Ranger recently. Unless he's been leaving invisible posts .

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    basscatt's Avatar
    basscatt is offline Cadillac Owners 10000+ Posts
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    Re: 1992 Deville bad gas mileage

    Quote Originally Posted by bessy2013 View Post
    02 Filter in mine was bad. Replaced it, gained 4mpg highway and town. Course that a mechanic's job because of it needing to be lifted to get at
    ---------------------------------
    02 Filter in mine was bad

    oxygen filter? -

    ----------

    Quote Originally Posted by MoistCabbage View Post
    That's the second time I've been confused with Ranger recently. Unless he's been leaving invisible posts .
    --------------------
    it must the similar WISDOM you both share -

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    dennis93coupe's Avatar
    dennis93coupe is offline Cadillac Owners Connoisseur
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    Re: 1992 Deville bad gas mileage

    Quote Originally Posted by MoistCabbage View Post
    That's the second time I've been confused with Ranger recently. Unless he's been leaving invisible posts .
    Oops!! Sorry Cabbage guess I better look at that a little more closely the next time. That's what happens when you start working 14-16 hour days at my age.

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