31 A stops after short start up

B

bgalla

Member
My 31 A stock has good flow to the carb, clean and steady. It starts easily but runs for 4 -10 seconds then dies. It will start up again almost immediately but dies again and does this repeatedly despite choke or throttle variations. The bowl valve occasionally will stick closed but responds with a blow. Help!
 
i think you should look for an electrical problem, if the bowl of the carb was full it would run longer than you say.
 
Check fuel cap vent although it will usually run longer if that is it.
Easy to check ,remove or loosen cap and see if it runs.
Next I would replace condenser with a known good one. Even though you have good spark they can be intermitent.
John
 
There is little fuel getting past the float valve (bowl valve). Remove the bolt under the carburetor that will drain it. There are two bolts there, the rear one is the drain. Put a bucket under the carburetor and turn on the fuel. There should be a strong steady flow of gasoline. Do this outside and have a fire extinguisher handy.
 
My money's on the condenser replace it with 1 of the burnout proof ones I've had a very similar situation with a factory condenser about 5 years ago it would start and then it would stall within few seconds!!!
 
I have helped so many people with this situation now, forgot how many. Like other posts above, I have found bad condenser numerous times!

However, I'm not ready to excuse the carburetor just yet. About 4 or 5 times, a piece of gunk has gotten into the main jet and plugged it when fuel was being drawn, then settled back down when the vacuum stops (engine stops rotating), allowing the jet to function again (for a short time). If it only happened once, I wouldn't even bring it up, but has happened more than once on cars that members brought to my shop.
 
My experience with bad condensors is that the engine will start but not run well. It will miss at all speeds and the points will burn. I don't think a bad condensor is the problem here.
 
Had a similar problem with my 31 frequently stalling and poor idle quality. Problems were completely corrected by a valve lash adjustment. When corrected be sure and tell us what the fix was. Good luck !
 
bgalla said:
My 31 A stock has good flow to the carb, clean and steady. It starts easily but runs for 4 -10 seconds then dies. It will start up again almost immediately but dies again and does this repeatedly despite choke or throttle variations. The bowl valve occasionally will stick closed but responds with a blow. Help!
Click to expand...

Sure sounds like a carburetor issue ! Start by cleaning the inside of the carburetor ?!
 
One more thing, I replied in the comments I thought look for electrical (it could be loose connection at terminal block, condenser, bad ignition wire etc , etc.) but the reason I said that was you claimed it would run 4- 10 seconds and die.My response was if the bowl is full of fuel tt would run much longer. Today I timed my car which idles at around 490 rpm. when running at idle and turning off fuel it took 55 second to die. The last 5-10 seconds you notice it getting rough. If it will start immediately after quitting and then run again for 4- 10 seconds it leads me to start the inspection for electrical.
 
Had the same problem with my ‘31 a couple months ago - had run great on way to a restaurant. After breakfast she started right up but died before I got out of the parking lot and behaved as described above - would start right up and die within a few seconds. Distributor was fine but I swapped in a second Zenith in the parking lot and she fired up and ran fine. In my case when I tore down the original carb I found the float valve stuck tight - needle firmly in the seat. Swapped in an old float valve and the original carb has been fine since.
 
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