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Thread: Tow vehicle woes

  1. #1

    Tow vehicle woes

    I pull my outfit with a '95 Chevy dually with a TBI 454. As of late, it has developed some kind of miss and general lack of power. The problem becomes apparent when pulling up big hills. Since I'm from VA, this is quite often. In a nutshell, the more throttle input I give, the worse it runs. I can feel a pulsation like its missing and power output decreases. If at that very instant I reduce throttle input, the truck will smooth out and actually make more forward progress. Although the temp. gauge indicates all is well, the engine seems excessively hot. The injectors appear okay. Changing the cap, rotor button, plugs, wires and o2 sensor didn't help.

  2. #2
    Senior Member DYNO OPERATOR
    Join Date
    Aug 2005
    Location
    Rifle Colorado
    Posts
    585
    Sounds like fuel delivery. Have you checked the fuel filter and fuel pressure? Checking the pressure is kinda tough on the TBI untits, but the best bet is to tee in at the filter with rubber hose. Should have around 14psi even at full throttle....

  3. #3
    Senior Member SENIOR BUILDER
    Join Date
    Dec 2007
    Location
    Morrison, Colorado
    Posts
    120
    A very common problem with these is the throttle body gasket. I can't count how many I've replaced. What happens is the engine sucks the gasket out from underneath the throttle body and it creates a large, unchecked vacuum leak. One thing you'll notice is a loud sucking sound and a higher than normal idle speed. It can also be harder to start. The MAP sensor will sense a different manifold pressure than what the other sensors tell it it should be, and the fuel curve can change as a result. It won't always turn on the check engine light either. Since the engine will be running leaner than it's supposed too, it can cause a lean misfire, power problems, and overheating concerns. Quick check is to check for hissing noises other than the normal noise from the throttle body. Then take some carb cleaner and spray it all around the base of the throttle body and plate under the throttle body if it's equipped with one. If the idle quality and speed changes, it's a sure bet that it's bad. The gasket is pretty cheap too, and they are easy and quick to change. Might just check it out anyway, since the carb cleaner will cost about the same as the gasket unless you already have some on hand. Hope this helps.

    Mark

  4. #4

    fuel filter

    Foir sure check ur fuel filter, my MH did the same thing. woodnt take throttle, changed filter and away she went. When I took it off, I coulnd blow thru it

  5. #5
    Junior Member APPRENTICE
    Join Date
    May 2007
    Location
    LAFAYETTE,LA.
    Posts
    16

    loss of power

    CHECK THE CAT CONVERTER IF IT'S CLOGGED YOU WILL LOSE POWER WHEN TOWING AND BUILD UP HEAT IN THE ENGINE.TRUST ME THIS HAPPENS ALL THE TIME. ops: ops: ops:

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