1950 Carter Carb. rebuilt now will not pump!!!

[OldCarCharlie]

Help, I did something wrong. The carb gummed up over last winter and when I went to pull her out it would not idle. Seems the pump wore out, so I have installed a new kit and she still will not pump. I took my time, dipped the parts, blem them out, rinsed and dried them all. I am fixxing to redo them all in hopes I missed something. Otherwise any and all advise will be helpful.

Thanks

[carbking]

Most accelerator pump circuits have an inlet check valve, and a discharge check valve. Did you make sure that both of these were not stuck in their seats?

Jon.

[OldCarCharlie]

Hi Jon, the discharge check valve. Is it located under the pump return spring? If so I will try and take it apart, have not yet. Looking at the parts list/diagram I am not finding an inlet check valve. However I am finding another check valve for the the discharge jets that I missed.

Charles

[carbking]

What is the carburetor tag number?

Jon.

[NTX5467]

IF that carb is like many newer carbs (at least into the 1960s and so), you can check the accel pump with the top of the carb (air horn) off to see if the accel pump plunger makes things work.

With the top of the carb off of the main housing, put a small quantity of fuel in the float bowl, probably about 1/2 full OR if the pump area fills directly out of the float bowl area via a slot in the accel pump casting, then enough for it to spill over into the accel pump area. Then, insert the accel pump into the bowl, getting it below the fill slot level, where the bore of the accel pump necks down to the "working area", and then gently and slowly push the accel pump plunger straight downward. If everything's working as it should, you should see fuel come out of the accel pump circuit before it goes to the "shooter" or come out of the discharge area itself.

You can also tell if the accel pump "cup" or "leather" is making a good seal against the bore of the accel pump casting, by the resistance you might feel moving it up and down in the bore. One of our chapter members had a carb for his '55 Roadmaster that had been rebuilt, but still had a slight flat spot upon accelerating off-idle. In a discussion with another BCA member, it was suggested that he go back to the leather accel pump unit rather than the newer rubber one. The leather can be roughed-up and such so that it could have a better seal against the pump's bore in the carb, whereas the rubber one was "as cast" and if it didn't fit well (allowing for a little normal wear), it could not be made to work as well as the fluffed-up leather one would. I seem to recall that the leather would also swell slightly, making it work better?

When you've determined that the pump can be made to work with the top of the carb off, then you can reassemble it and it should work good.

A good while back, I had used some sodium-based lead replacement additive in one of my cars. After I'd let it set for a few months, I wanted to get it out for a show, but it was very hard to start (i.e., getting it to fire-off, not crank over). I determined that the accel pump was not working, yet the linkage on the ThermoQuad was working normally. I finally got it to start and went to the show. When I got back, parked it, and then checked it the next day, I took the pump discharge "shooter" off and found the weighted check valve (a pointed, cylindrical piece of metal, to keep fuel from being pulled into the air stream via the discharge shooter) was stuck in its bore, effectively sealing up the accel pump circuit prior to the discharge shooter. I freed it up and it worked great ever since. I stopped using that particular additive, too.

Just some thoughts,

NTX546

[OldCarCharlie]

Hi Jon and thanks for all the help. The other night I was prowling in the shop and found my Shop Manual for the 1950 Buick(the Bible) and it shows a very detailed carb and nice step by step instructions(4-5 pages). It also covers everything you suggested.

I will dig back into the carb this weekend and am 99.9% certain I can it to pump.

Once again Jon, thanks and thanks to all the other help.

UB