Pain at the pump and the inspectors

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HT4100 4.1, 4.5, 4.9 Discussion, Pain at the pump and the inspectors in Cadillac Engine Discussion; My car has been sucking up gas like crazy lately. I am only getting about 13 mpg on the highway ...
  1. #1
    johnplara is offline Cadillac Owners Fanatic
    Automobile(s): 1993 Green Goblin Sedan Deville with the heart of a 91
    Join Date
    Aug 2005
    Whitesboro, NY

    Pain at the pump and the inspectors

    My car has been sucking up gas like crazy lately. I am only getting about 13 mpg on the highway at about 65. The car also smells like it is running seriously rich. So I tried many things to fix the problem. I changed the coolant sensor, verified there is signal going to it. Adjust the ignition timing to the specs on the car, replaced the plugs, air filter,oil change, oil filter, the spark plug cables, cap, rotor, checked fuel line PSI, 37 and holding steady, even after the car is shut off. put fresh 89 in the tank, TWICE by now! To recap, The engine in my current 93 caddy came original off my 91 Deville. I bought this 93 cheap because the previous owner did not believe in sealant tabs and lets just say not only the head gasket was messed up, and this only after 70K. Naturaly I put in the engine from my wrecked 91 deville that had 105K and was running fine on a wonderful gray Deville....untill I let the GF drive it. In anycase...HELP! I don't want to kill the catalyst or lord knows what else.

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  3. #2
    HUF's Avatar
    HUF is offline Cadillac Owners Connoisseur
    Automobile(s): 1995 FWB 100,*** miles CURRENT. 1991 Seville 175,000 SOLD
    Join Date
    Dec 2005

    Re: Pain at the pump and the inspectors

    Things to check out:
    FPR - fuel pressure regulator (close to throttle body). Start the engine. Pull a vacuum line off the FPR. There should not be any fuel present.

    Oxygen sensor. $30 part.

    Fuel injectors. At least unplug the common connector for 4 injectors (one connector per fuel rail). One of connectors is 8 pin, the other is 10 pin. Measure the resistance between vertical pairs of pins. You'll figure out. The ballpark is 17 ohms. I did mesure mine today and some of them were as low as 8 ohms... They all were fine last summer!

  4. #3
    awadecki is offline Cadillac Owners Enthusiast
    Automobile(s): 76 Eldo (54k), 76 Eldo (52k), 78 Eldo (9k), 85 Deville (43k)
    Join Date
    Jun 2005

    Re: Pain at the pump and the inspectors

    Probably bad injectors. One reason why I buy and sell all my 4.9s before they get to 75k miles.

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