1954 Carter YH accelerator pump

[Peter R.]

My '54 won't start cold without the help of a spray of ether or a squirt of gasoline. Once I get it started and it has run briefly, it will restart easily. When I look down the barrel of any of the carbs and actuate the throttle linkage, I see only a dribble of fuel from the accelerator pump jet. Is a dribble normal, or should I see a healthy stream exiting the accelerator pump jet? I have checked the accelerator pump diaphragms (I replaced one that looked damaged) and the check balls in the pump circuit. My suspicion is that the passage leading to the jet (or the jet itself) may be restricted by varnish buildup. And it looks like the most direct access to that passage is through an aluminum plug on the bottom of the carb. Prior to this problem, the engine had not run for a few years, which undoubtedly contributed to the problem. I would appreciate opinions and/or suggestions.

[Jim L.]

Re: 1954 Carter YH accelerator pump

Pete, the dribble you describe doesn't sound right. All carburetors I've seen will issue forth a strong squirt of fuel from the accelerator pump. I have a '54 also however I've never tried to look down the carbs' throats to see what they do.

One practical way to determine if the dribble is "normal" or adequate would be to note if the engine stumbles when you press the throttle to accelerate the car, particularly from engine idle. A stumble would indicate a momentary lean condition suggesting a problem with the accelerator pump. OTOH, if the engine pulls away without a stumble, it's getting enough fuel at the right time. Therefore the dribble is "normal".

FYI, my '54 will start without pumping the throttle. My technique is dead simple: Pull out the choke and crank the engine. At the instant the engine lights off, push the choke all the way in.

Hope this helps....

Jim

[Peter R.]

Re: 1954 Carter YH accelerator pump

Thanks, Jim. I just tried your starting method and it didn't work for me, but I might know why. From further research on this forum I found a thread based on the exact same problem I'm having.

(https://www.forums.ncrs.org/showthre...=1954+starting)

And it answers the question of whether the accelerator pump dribble is normal. Apparently it is. According to two posts in that thread, one from Terry McManmon and one from Chris Sherman, the accelerator pump in the Carter YH is not like that in later carbs; vacuum is needed in the carburetor throat while cranking to draw fuel from the accelerator pump jet. And choke plate adjustment is critical. I just checked my choke plates with mirror and flashlight and they were not fully closed when the choke knob was pulled all the way out. This would lessen the vacuum needed by the accelerator pump(s). I adjusted the choke cable on each carb so that the choke plates are now fully closed when the knob is all the way out. I haven't try starting the engine after this adjustment, but I will, and I suspect this will make a difference.

[Peter R.]

Re: 1954 Carter YH accelerator pump

Today I was able to start the car with Jim Lockwood's method (crank with full choke and no pedal until engine starts; then push choke fully off). It appears that yesterday's choke plate adjustment made the difference. Starting problem solved, thanks to the forum.