Zenith carb

Quick question for you carburetor gurus.. I have a stock green diamond 214. Overall the engine runs well but after sitting for 15 minutes it is hard starting. Sitting for a long time or a very short time it fires right up. I’m thinking that the carb is letting gasoline in after shut down causing flooding.

Are parts, kits etc. easy enough to come by? Would another manufacturer such as Stromberg be better ? Trying to keep stock if possible.

Thanks All,
Bob

Quick question for you carburetor gurus.. I have a stock green diamond 214. Overall the engine runs well but after sitting for 15 minutes it is hard starting. Sitting for a long time or a very short time it fires right up. I’m thinking that the carb is letting gasoline in after shut down causing flooding.

Are parts, kits etc. easy enough to come by? Would another manufacturer such as Stromberg be better ? Trying to keep stock if possible.

Thanks All,
Bob

Bob,

Yes kits are available. you will need a number from the carburetor. I found a site with the information you need to ID the Zenith and find a kit.

http://www.thecarburetorshop.com/Carbshop_kits.htm

Next time drive it without the air cleaner on it and after you shut it off look down the carb with a strong flashlight.
It may take a minute or two to see what you need to see.
If you see fuel rolling out of the main discharge nozzle hot with the engine off you can have more than one possible problem:
1) Sure the carb can be malfunctioning/ flooding. It may need to be rebuilt.
2) A common problem with unpressurized gasoline (unpressurized carbs vs. pressurized fuel injection) is that too much intake manifold heat can cause fuel to boil.
3) you can make or buy a phenolic spacer to place in between the carb base and the intake manifold.
Many, many carbureted vehicles came from the factory with a carb phenolic spacer installed. No unproven technology, here. This spacer slows down heat transfer from the intake manifold.
4) it's also possible that the engine is running too hot, causing fuel to boil in the carb or that the heat riser is stuck in the hot position. Can't blame the carb for that.
5) these carbs run on relatively low fuel pressure. It's possible that the fuel pump is developing more pressure than the carb can handle. Most American stuff I've worked on the fuel pressure should be like 3-6 psi.
6) the same way the carb can be insulated from heat via a phenolic spacer so can the mechanical fuel pump, if used. Again, many carbureted vehicles came with a fuel pump phenolic spacer.
7) I've learned through hard experience that all other possibilities should be explored before immediately condemning an otherwise functioning carburetor.
8) best of luck!

Ok. Thanks for the input. Earlier in my life when I was fooling with cars to see who had the fastest street cars I often times blamed carburetion but it ended up being ignition.

We ( my son and I ) took the KB for a lunch time adventure today to only find the drive quite problematic. The old girl hiccuped a few times and then started dying on us. I managed to ease her home by closing and opening the choke. It seemed as thought I needed the choke to draw fuel but after a stall and restart it seemed to run better. Not trusting the reliability we headed and made it home.

After some household chores I started my preliminary investigation. Thought process ; if I needed the choke to pull fuel maybe the fuel pump is not producing enough flow. Then maybe the in-line fuel filter is slowing the flow. The carburetor had been acting well except for maybe letting of some gasoline into the cylinders after a fifteen minute shutdown. I don’t have a gauge to check fuel pump pressure to see if it forcing gasoline past the needle valve.

So what did I do ? I checked the points and found the gap a bit wide and adjusted it to about.019”.
I replaced the vertical, metal inline fuel filter with a plastic one so I I could monitor the fuel. When I cranked the engine for a short time the filter only drew fuel into the bottom 1/4. Chocking did not seem to pull more into the carburetor. I finally got it fired up and it runs well at idle and also when revved while sitting stationary. I’ll Drive it tomorrow and see what happens. I strongly suspect the fuel pump which looks fairly new.

Ok. Thanks for the input. Earlier in my life when I was fooling with cars to see who had the fastest street cars I often times blamed carburetion but it ended up being ignition.

We ( my son and I ) took the KB for a lunch time adventure today to only find the drive quite problematic. The old girl hiccuped a few times and then started dying on us. I managed to ease her home by closing and opening the choke. It seemed as thought I needed the choke to draw fuel but after a stall and restart it seemed to run better. Not trusting the reliability we headed and made it home.

After some household chores I started my preliminary investigation. Thought process ; if I needed the choke to pull fuel maybe the fuel pump is not producing enough flow. Then maybe the in-line fuel filter is slowing the flow. The carburetor had been acting well except for maybe letting of some gasoline into the cylinders after a fifteen minute shutdown. I don’t have a gauge to check fuel pump pressure to see if it forcing gasoline past the needle valve.

So what did I do ? I checked the points and found the gap a bit wide and adjusted it to about.019”.
I replaced the vertical, metal inline fuel filter with a plastic one so I I could monitor the fuel. When I cranked the engine for a short time the filter only drew fuel into the bottom 1/4. Chocking did not seem to pull more into the carburetor. I finally got it fired up and it runs well at idle and also when revved while sitting stationary. I’ll Drive it tomorrow and see what happens. I strongly suspect the fuel pump which looks fairly new.

Sounds more like the main jet is clogged in the carb. Pulling the choke makes the vacuum from the engine pull fuel due to the lack of air. Before throwing parts at it, make sure the passages in the carb are clean and free.

I would get the rebuild kit just to rebuild it and know everything is working. I did mine as the engine would not fire unless you put your hand over the carb to get the air/fuel to draw and then it had no real acceleration when you hit the pedal down. It ran OK at idle as long as I kept my foot in it to keep the RPM's up a little.

There is a little steel piston in the carb used as the accelerator pump. Mine was stuck solid from age and sitting, but the carb was very clean inside. The new kit (mine was a KB5 228 model carb) replaces the steel piston with a standard/typical rubber type accelerator pump which is compatible with ethanol laced fuels. Very easy carb to rebuild and there is a video on YouTube showing how to do it step by step. I also got my rebuild kit from "Mikes." https://www.youtube.com/watch?v=4TTFFZ95fjI

Have not fired up the truck to see how the rebuilt carb works as I am working on other engine items the KB5 needs as well.

Ok Guys; all good input. I have not yet pulled the carburetor. Over heated fuel was also on my mind as a possibility for fuel getting into the engine after shutting down. There is already a spacer between the carb base and manifold but don’t know if it’s adequate..we’ll see. The next run will be a bit longer and I will pull the air cleaner and take a good look down the throat of the carb.

After resetting the points and replacing the fuel filter I took it for about a two mile ride. The engine performed well and seemed to accelerate with no hesitation . After the short jaunt I observed that the fuel filter was full and clear. When dumping the fuel from the old filter I saw no contaminates (at least in the fuel spilling out). The engine actually seem to accelerate a bit smoother than previously and I’m thinking that maybe resetting the points helped.

Thanks,
Bob

Thanks for the rebuild kit information. A longer drive today will determine whether I’ll go in that direction.

Bob

The carburetor MAY need rebuilding, but this link probably explains the difficult hot start issue:

http://www.thecarburetorshop.com/Troubl ... rdstarthot

Jon.