Sounds like the carb needs rebuilding even if it is not the problem.
Put a temporary fuel pressure gauge to see what the fuel pump is doing.
Meanwhile check the point gap and the condition of the point contacts.
Senior Member
It's hot here...90+ in Colorado Springs, but lately I am experiencing what can only be initially described as vapor lock. It's bizarre, in the morning it's perfectly fine. Runs all the way to work with no issues. Yet after work (5am-3pm) I get maybe 5 minutes of driving and it starts losing power, cackling, backfiring then dies. If I get out and close the choke on the carb, I can get it fired back up for maybe 2 more minutes of driving. If push in the clutch and take the load off, the engine, it will stay running a bit longer. I can flutter the gas pedal and coax it along... I stalled out by my house this afternoon, gave it 5 hours to cool and went to drive it home, hard start and it stalled out 4 more times in the 3 minutes it should have taken to get home. Each time I got out and was able to restart it. I got it in the driveway and it idled just fine. Stayed running longer than it did when I was driving it.
Things I know:
1. I am not blowing any smoke out the exhaust pipe
2. I get a bit of smoke out the breather in the valve cover when I try to start it.
3. It feels hot, the radiator tank was hot to the touch I could hold it for maybe 4 to 5 seconds...
4. The coolant appears to be clean, not muddy with oil.
5. This problem has been getting progressively worse over the past three weeks. Meaning: It happened once then it was fine, a few days passed then it was fine, and now, it's after 4 minutes of driving...too frequent to count.
Carb was REALLY gummed up at the choke plate...It was not operating properly. The plate was hanging up and not moving as it should. Did not open at all when you gave it some gas, was pretty much stuck closed. I shot a metric crap ton of carb cleaner in there to loosen things up.
*** This weekend
I let the car warm up till the tank on the radiator was hot, wired the choke wide open and buzzed around, no issues...
**** The next morning
I took the Buick out to get doughnuts this morning and It had a slight stumble on the way to the store, almost dying, when I let off the gas. It had a bit of a cackle in the exhaust when I let off the gas on the way home, but no issues. ... I would assume a complete carb rebuild is in order. What are the specs are for the fuel pump as it's probably never been replaced? It would seem as though I have a fuel issue. Any other ideas?
This morning I drove to the grocery store, the poor thing wants to die when I let off the gas after I drive it a bit. Yet when idling it does just fine. I took it all over went to hose it off, left it running to warm up properly when I did, drove it home and it up and stumbled when I went to get it in driveway.
Senior Member
Sounds like the carb needs rebuilding even if it is not the problem.
Put a temporary fuel pressure gauge to see what the fuel pump is doing.
Meanwhile check the point gap and the condition of the point contacts.
Senior Member
I had some weird stuff happening once with crap in the fuel line. Took the tank off and put some round pebbles in and shook it for awhile knocked a lotta stuff out of it. Blew out the line, and cleaned/replace fuel filters.
Senior Member
Carburetors do not suddenly go nuts. I would check your fuel feed system from one end to the other. If you haven't cleaned out your gas tank, do that first, then check fuel filters, feed lines, especially rubber lines, as they can deteriorate on the inside and block flow. Also, make sure that your gas cap is breathing. Air must get into the tank to replace fuel drawn out or a vacuum will occur that will stop fuel flow dead. Due to the crap that passes for gasoline these days, I always install an electric fuel pump as close to the tank as possible and wire it through a switch so it can be used as backup as well as when the car has been sitting a long time and the fuel in the system has evaporated. Run it for a minute or two before hitting the starter. This pump will also push vapor lock through and keep the engine running when the stock pump won't. Good luck.
Member
My take on most vapor lock is a leaking fuel line. The pump sucks on the fuel line back to the tank and if you have even a microscopic leak it will draw air bubbles into the fuel line. Think of a drinking straw with a hole in it. When those bubbles get heated by the engine, vapor lock occurs. A electric fuel pump by the tank will solve it, but you still have a leak. dropping the fuel tank to do a pressure test in not a fun. I would look for leaks
joe
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