Model A Starts, Runs, Dies... repeat...

Car54

Car54

New member
Hey, folks! I've popped in here from time to time, but I think this is my first cry for help. I'll write a story here so you have as many facts as I can think of.

Our Model A was running fine, but it had gas leaking at the sediment bowl and both ends of the fuel line to the Zenith carburetor. I disassembled the sediment bowl, cleaned it up, and reassembled it with a new neoprene gasket. I removed the gas line, installed new fittings at each end, ensured that fuel ran through the line, and reconnected it. I started the engine. It ran fine for about 30 seconds, then quit like it had run out of gas. I could restart it and it would run 10-15 seconds and quit again. Suspecting I could have dislodged some crud during the process, I checked the filter screen in the carb. No apparent trouble there. Well, we had a rebuilt carburetor all sealed up in plastic and sitting in a drawer. So, I installed it, made the necessary connections, and attempted to start it. It ran about 30 seconds and quit. I can restart it, it runs a little and quits; same as with the other carburetor.

Idle is set as well as we can. GAV is open 1/4 to 1/2 turn. If turned off completely it won't run. Opening more does not help.

So, it looks like the bottom line is I must've put something together wrong, but what? Any ideas?
 
You may have installed the gas line too far into the carburetor, or you have the tube extending too far past the ferrule. If that happens, it will butt up against the filter screen and restrict or stop the flow of fuel into the carb. The ferrule should be flush with the end of the tube.
 
700rpm said:
You may have installed the gas line too far into the carburetor, or you have the tube extending too far past the ferrule. If that happens, it will butt up against the filter screen and restrict or stop the flow of fuel into the carb. The ferrule should be flush with the end of the tube.
Click to expand...

Thats my vote!
 
In weird cases like this when ruling out if it MIGHT be ignition loss, mistaken for carb problems I do this: Use an old coil wire, cut it in two a few inches below coil, peel back insulation, pass the two wires through two opposing holes in a small button and twist wires tightly. The spark jumps the small gap and lets you know if you have consistant spark. While trying to get carb diagnosed, just keep your eye on the spark jumping the button, in case it might be spark loss, mistaken for carb problems. Bad condensors will sometimes run at low speeds and crap out at higher R.P.M's. I've also seen a tight bushing where the point moveable arm is tight on the pivot post and it might run at low R.P M's, but has trouble closing the points at higher R.P.M's. A drill bit ran through the bushing will fix it. Save the test wire, it's a GOOD Okie test tool. Chief showed me this trick! The Bible says that our looks & personalities will be know as we are in Heaven, I wonder if there Model A's there to be FIXED, or do they run PERFECTLY there????? Bill W.
 
Have you tried removing the carburetor line to see if you have a good steady fuel flow ?? Extending the line too far into the carb seems to be a somewhat common problem like the fellas said..
 
I wonder if the neoprene gasket could be somehow blocking the outlet from the sediment bowl. I vaguely recollect there being a fitting problem with those.

Steve
 
steve s said:
I wonder if the neoprene gasket could be somehow blocking the outlet from the sediment bowl. I vaguely recollect there being a fitting problem with those.

Steve
Click to expand...

Glad you mentioned that Steve. For sure you want to remove the neoprene gasket and install the cork gasket. I've seen and heard what ethanol does to the neoprene.
 
Patrick L. said:
Have you tried removing the carburetor line to see if you have a good steady fuel flow ?? Extending the line too far into the carb seems to be a somewhat common problem like the fellas said..
Click to expand...
Pat,
I was so surprised when checking fuel flow at carb end of fuel line, with just under 1/2 tank, the line flowed a 5 to 6" stream of gas!! That made me KNOW for sure that the little stainless standpipe filter in the top of fuel valve DOESN'T impede or slow down the fuel flow. That filter is a MUST have item!! Bill W.
 
The guys mentioned extending the fuel line into the carb too far. The same thing can happen at the sediment bowl end. That's where I've seen this happen most often. You slip the ferrule onto the line and stick the line into the sediment bowl and tighten the fitting not realizing the end of the line is up against the casting inside blocking the fuel flow.
 
sounds like it's not getting gas forsure.. These guys are on the right track. I also noticed with my sed bowl that I had tightened it too much and wouldn't allow the gas to flow. Make sure the top of the sed bowl is filled. Also check good flow to carb.
 
Congratulations, Larry S! You are the winner! :) I trimmed off the excess tubing at the sediment bulb end of the line and voila! We're on the road again. I fool kinda feelish admitting that :o as I had already checked the carburetor end of the line in anticipation of such a problem.

Anyway, it's all fixed and running fine. Thank you, everyone, for your suggestions!
 
Thanks for letting us know. Now we'll all check both ends of the fuel line when this problem comes up in the future. And it will!
 
Larry Seemann said:
The guys mentioned extending the fuel line into the carb too far. The same thing can happen at the sediment bowl end. That's where I've seen this happen most often. You slip the ferrule onto the line and stick the line into the sediment bowl and tighten the fitting not realizing the end of the line is up against the casting inside blocking the fuel flow.
Click to expand...
Thanks for that fact about blockage at sediment bowl inner wall! I never heard of that possibility. Bill W.
 
You must log in or register to reply here.
Back
Top