dry carb

Discussion in 'The Venerable Q-Jet' started by hvramesq, Jul 29, 2019.

  1. hvramesq

    hvramesq Silver Level contributor

    Hi guys,

    I have the stock q-jet on my 70gs455. sometimes I don't start the car for a week. its garage kept, but I'm in S. Florida, so the garage is anywhere between mid 70s and high 80s during the spring and summer months. but I have the same issue in the fall and winter months, which are just a little cooler. The issue is that when I go start the car, which is often after 5-10 days after last use, the carb is bone dry and I have to pump the hell out of it at start up. Is this natural vaporization of fuel in the carb or indicative of some other problem, i.e. leak in line. How long should you expect the gas to last in the carb. does the hot engine itself evaporate the gas within a few hours.
  2. pbr400

    pbr400 68GS400

    Some of it could be evaporating, but most likely the main wells are leaking.
  3. hugger

    hugger Well-Known Member

    Check valve fuel filter will help
  4. TORQUED455

    TORQUED455 Well-Known Member

    One little trick to help keep fuel from siphoning back out is to remove the little wire hanger from the needle. As the fuel evaporates, the float drops and siphoning can occur. This prolongs the inevitable for engines that sit for a while.
    techg8 likes this.
  5. Brad W

    Brad W Miles from nowhere...

    I have a '72 Skylark with a 350-4. I live in California with kinda the same weather and what worked for me was to look in the owners manual and read what Buick said about starting their cars. So what I do is if the car is cold push the accelerator all the way to the floor once then let off and with my foot off the gas start the car with out pumping the gas, then it starts.
    I've found that after a week or two my car has been sitting if iI use the same technique but let the engine crank a little longer to let the gas pump get the gas back into the carb it's still stats fine, just take a few cranks longer.

    I've had the car sit for up to three weeks and this still works. I used to pump the gas peddle but then I would end up flooding the motor.
    TimR and gsx455-4ever like this.
  6. gsx455-4ever

    gsx455-4ever Gold Level Contributor

    Yes it could be the well plugs leaking down and evaporation . But ...............

    I don't understand the need to "PUMP " the hell out of it . Set the choke with 1 push to the floor and crank . It may take 4 to 6 revolutions for the engine to start but it will if the choke is closing properly . All you are doing with the pumping is wearing out the accelerator pump .

    The time it takes for the engine to start I would consider " Priming " as it is sending oil to the bearings .

    I have cars that sit for months and take 4-5 revolutions to start but do so with 1 pump to set the choke . They then run at fast idle until I kick it down
  7. gsx455-4ever

    gsx455-4ever Gold Level Contributor

    Agreed and Correct 110%
  8. Quick Buick

    Quick Buick Arlington Wa

    I 3rd that..
    gsx455-4ever likes this.
  9. Cliff R

    Cliff R Well-Known Member

    If the carb is empty pumping the accl isn't putting any fuel into the engine. You need to crank the engine long enough to put fuel back in the fuel bowl. Once this happens one or two pump shots and it should roar to life.

    This assumes the choke flap is tightly shut and the accl pump cup is in good shape, which it may not be. Most of the accl pump cups don't hold up well in this new fuel and may not delivery a good pump shot after periods of drying up.......Cliff
    Quick Buick likes this.
  10. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    I’ll tell you what I do. I get a container of non ethanol gasoline from Home Depot. It is called truefuel. I bought a plastic bottle with a thin spout from Amazon. I then just fill the fuel bowl through the vent. Anything longer than 3 days or so and I need to do this. I think the gas evaporated out from the engine heat initially. I find it worse in the winter with the winter blend fuel that is more volatile.
    Quick Buick and Brett Slater like this.
  11. lemmy-67

    lemmy-67 Gold Level Contributor

    If your carb is stock from 1970, it probably has the lead-filled well plugs & shouldn't leak at all. It's probably the engine heat after parking it that's speeding the evaporation of the fuel in the bowl. After driving my 67 on a hot day in stop/go traffic, I park it in the garage with the hood up, helps the engine bay cool faster without heating the carb up. All that heat & no fan will boil the fuel out of the carb with the hood down.
  12. hvramesq

    hvramesq Silver Level contributor

    thanks guys. I did dramatize with my pumping description. I have read the cold start procedure and have been using it and of course it does the job. I just hate extended cranking on a 9ok+ motor. The carb is a stock q-jet but was rebuilt by a board member 2 years ago. my mechanic recently serviced car and said the choke was not working well. at start, my car will not fast idle and i have to pedal it toll it warms up enough to let foot of gas. I am thinking about getting an electronic choke. if any one can give a Q-Jet 101 version of how to check and fix well plug leak, it would be much appreciated.
  13. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    If your carburetor was rebuilt by Ken or Mark, I am sure the well plugs were sealed. Cranking is more of a hardship on your battery and starter, not the motor. Sounds like your problem is a combination of things, fuel evap from the bowl, and non functioning choke. Ken sells an electronic choke conversion.

  14. Brett Slater

    Brett Slater Super Moderator Staff Member

    I do the same thing.
  15. Quick Buick

    Quick Buick Arlington Wa

    To see if your well plugs leak. remove from motor ,,, empty the gas.. put cab on a stand of a sort.... fill carb with acetone. you may have to pump the acetone though the carb to make sure its full...Acetone is thinner than gas it will find a leak if there is one. Will the Acetone harm the seals?? I have no 100% true answer.. Im sure someone does
    Last edited: Jul 30, 2019
  16. BQUICK

    BQUICK Well-Known Member

    Electric fuel pump
    sean Buick 76 likes this.
  17. 436'd Skylark

    436'd Skylark Sweet Fancy Moses!!!!!

    Realize that this isn't an EFI car that instantly primes the fuel system and starts with half a revolution. What may seem like a long or hard start is probably normal for a car with a carb. 5-10 second cranks are no problem. Set the choke and let it start on its own. Constant pumping is incorrect and causes more trouble. If that's the only way it starts then you have choke issues.

    If your fuel plugs are leaking it would be more of an issue with hot starts than cold
  18. sean Buick 76

    sean Buick 76 Buick Nut Staff Member

    My 75 starts in about 8-10 seconds after sitting for 6 months so something is wrong for sure. I just pumP the gas 5 times and then crank it over till it fires. if it’s only say a week or two then two pumps of the gas. And if it’s ran that day I just floor the gas once to set the choke.

    I think it’s a weak fuel pump that’s causing your issues.

  19. Cliff R

    Cliff R Well-Known Member

    The carb should re-fill quickly even if the bowl is completely dry. If it doesn't there is an issue someplace in the fuel system or a problem inside the carburetor.

    I owned a 1985 Caprice for quite a few years (carbureted). It would often sit for weeks or even months. It took 1-2 cranking cycles of 3-4 seconds to re-fill the carb no matter how long it set. Then just 2 or 3 pumps of the throttle and it would roar to life instantly.

    I continue to read thread on the Forums where folks have to end up raising the hood and manually priming the fuel bowl or putting fuel directly into the engine to get some of these cars to fire after long periods of sitting. IF you are having to do that there are other issues going on, like the pump seal shrinking and needing to get wet again and swell up a bit before it will start putting fuel back in the engine.

    I've also seen a few set-ups where they were sucking air at rubber hoses that weren't in good shape or loose clamps, etc........Cliff

Share This Page