It's driving me nuts!

Jim Kilday
Jim Kilday Expert Adviser
edited November -1 in HUDSON
After 18 months of work, my 46 Commodore Coupe is purring like a kitten--well, most of the time she purrs.



After replacing the complete fuel line, new electric gear fuel pump, mechanical pump rebuilt by Dave Kostansek, new fuel pressure regulatior, carburetor re-manufactured by Daytona Parts, gas tank cleaned and sealed the car runs great EXCEPT occasionally after it has run for an hour or so--in traffic or on the open road--it will act like it's not getting enough fuel and will not exceed 40 mph for love nor money. Once it wouldn't exceed 20 mph but only once. Usually it is 40--40 and floored!!!



When it isn't misbehaving, she will cruise down the highway at 60-65 and never misses a beat.



I let it sit for a couple hours or overnight and and it always runs fine and may not act up for days, then BANG, it's up to its old tricks.



Pertronix ignition, new coil, new plugs. I spent enough money on on this old girl to burn a wet mule and it acts like this!



My instinct tells me it has something to do with the operating temperature but since I know next to nothing about the finer points I'm only guessing.



Any ideas???



Jim Kilday

Comments

  • Richard E.
    Richard E. Senior Contributor
    Sounds to me like vapor lock! Do you have the electric fuel pump turned on when this happens? If not, will turning it on alleviate the problem?
  • Jon B
    Jon B Administrator
    When it acts up, and you pull to a stop, does it idle smoothly? This is an off-the-wall guess, but you might have an intermittent valve timing problem caused by a faulty fiber timing gear. The hub can become separated from the outer part of the gear, so that the camshaft is no longer in sync with the crankshaft. Then the outer part of the gear with "shift" suddenly and go back in sync. But, if your car idles smoothly (during one of the times the car won't go over 40), then that shoots that theory!



    Another wild guess would be the advance, on the distributor.
  • rambos_ride
    rambos_ride Senior Contributor
    My guess is the fuel is getting too hot - check your fuel line routing to see if you're too close to an exahuast or that a rubber fuel line isn't collapsing.
  • Uncle Josh
    Uncle Josh Senior Contributor
    Or, that a slug of tank sealer hasn't gotten near the pickup tube.
  • Unknown
    Unknown
    Uncle Josh wrote:
    Or, that a slug of tank sealer hasn't gotten near the pickup tube.
    another possabilaty is the carb itself boiling in the fuel bowl, Have you got a 1/4 inch heat sink spacer under your carb?
  • Clutchguy
    Clutchguy Senior Contributor
    Quote from UJ, "Or, that a slug of tank sealer hasn't gotten near the pickup tube" this is very possible.



    Something else I have seen is the cloth in the lid of the air cleaner-provided it has the Original type air cleaner on it-comes loose and covers the carb.and won't let the engine get any air,really noticeable when you are running the engine at higher RPM,and once it starts acting up,it won't recover until the engine shuts off. Drive it with the air cleaner off,and if it does shut off I would be prepared to get out and check it for spark right then. You might have someone else with you to assist.
  • Unknown
    Unknown
    The symptoms you describe sounds like 1 of 2 things,

    either you are vapor locking or you have an intermittant

    problem with airflow like what was described in an earlier post

    the cloth may be blocking the air into the carb.

    Just had this problem a couple of months ago my Sons car

    would not go over 35 to 40 mph. idled beautiful. found blockage in

    air cleaner that at lower speeds did not imped but when trying to accelerate or get up to traffic speed the paper would get sucked up to filter and restrict the air flow.

    Hope you find the problem I know how frustrating that is.

    Wayne
  • Richard E.
    Richard E. Senior Contributor
    What about your exhaust damper? Mine was sticking shut and it super heated the fuel and caused problems. I finally wired it open as we really don't need them here is So CA.
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