The Stovebolt Site Forums The Shop Area Engine Shop Hard Starting when sitting overnight

Any time my truck, 1953 Chevy 3100 with a 54 235 in it single barrel carb recently purchased rebuilt from Chevy Duty, is left overnight it will not start. Even with three pumps and full choke, nada.

I have to give it a squirt of ether, full choke and fire it up. It will idle fine with no choke after about 10-15 seconds. It will start fine for the rest of the day, even if it sits for five or six hours.

The other problem is that it bogs when going from idle to full or 1/2 throttle. More of a hesitation I should say I can ease through it by pushing on the throttle slowly until about 1/4 throttle then I can floor it and it runs fine. It is less of an issue as it warms up but it does not go away.


Other than these two things it runs great. I just finished removing dual carbs and dual exhaust and returing it to stock. Next is putting period appropriate wheels and tires on.


Hugh

Hmmmmm- - - - - -
Try a little diagnosis at the next cold start. Pull the air cleaner, and see if the accelerator pump is squirting any fuel into the carb venturi before you crank it. If not, pull the fuel line, and crank for 10 seconds or so with the line going into a catch bottle. This will tell you if you're dealing with a dry carb, or a fuel pump that's losing its prime.

A fuel pump has one-way check valves that should prevent the gas from draining back toward the gas tank. If you crank it against a vacuum gauge attached to the inlet line, it should pull about 10" of vacuum, and hold it for some time (maybe 15 seconds) after the pump stops operating. Ditto on the outlet side, up to 3 or 4 pounds of pressure, and this should also hold for a while. If either vacuum or pressure is low, or won't hold its value for a while, trash the pump! Also check for air leaks or restrictions between the tank and the fuel pump. Pinhole air leaks on the inlet side are bad about letting a pump lose its prime, without making any puddles!
Jerry

PoPo;
My '49 with a 261 does the exact same thing. Gonna check the tank to pump line like Hot Rod suggested cause I think the fuel is draining back from the carb. Let me know if you have any success and I will do the same. May not get to it for a while as it's still a bit cold here!

I'll give it a shot today.

Hugh

My 54 248 GMC does the same thing. A little gas down the throat and it starts just fine. I will change the fuel pump when I get the time.

I'd say it's got to be one of the two things HotRod said. My two cents goes to the accelerator pump, because of the hesitation when changing the throttle position, but the pump could be bad too.

I put a new fuel pump in last year, but that doesn't mean it isn't the problem. Now I just need to see if my 3 year old will let me work on it with too much "help". On the positive side he loves tools and thinks gasoline smells good.

I tnink the two problems may be separte. Because it doesn't matter how much I turn it over or what choke and throttle procedure is used it won't fire at all. A small shot of ether with full choke and it starts immediately and keeps running. I could kill the battery otherwise.

The accelerator pump is the most likely cause for the hesitation but it is only a problem at low throttle, such as immediatley after changing gears. Once I get to 50% throttle I can leave it or floor it with no hesitation.

In respect to timing I used the vacuum tuning method. Set the idle to just above stalling and adjust the timing to maximum vacuum and then back it off a little. It runs better than when it was adjusted with a timing light but now requiers ether to start.


Hugh