To me this describes percolation or fuel boiling out of the carburetor bowls. The electric pump will help a cold start, but not the hot start, or the stalling from a light.Įdited Septemby carbking (see edit history) Personal experience is how I learned the issue, and how to bypass the issue. Daily drivers from the 1970's and 1980's which I have had exhibited exactly the same symptoms, although most of mine were standard transmission, so easy just to rev the engine in neutral. This will clear the puddling and air cleaner vapor issue, and the car will run normally. Under these conditions, if an automatic transmission, place the transmission in park toward the end of the light, and rev the engine to 1500~1800 RPM for maybe 5 seconds. The insulation provided by the OP proves the issue, as the insulation made the effect significantly better. The same thing happens when the engine sits for a period of time idling, except that fuel both "puddles" in the intake manifold, and also vapors fill the air cleaner. The above link describes what happens when the engine is turned off. The symptoms mentioned by the OP in post 1 are NOT a result of vapor lock, rather exactly the opposite (too much pressure)! The first issue is understanding the issue! All the time getting upset that people keep telling me to post updates only in the "modified" section of the forum. Next thing I know I'm doing a full Tesla battery and drive train conversion in the Roadmaster and using the turbo-efi nailhead for my Cub Cadet. First the fuel pump, then I might as well do a Holley efi, then upgrade to a direct injection megasquirt system. I have thought wistfully about an electric pump at the tank but am concerned that it is a slippery slope. Today was pretty hot too, so I hope I tested the upper extremes. When the engine is idling, pulling fresh fuel, and the fan is pulling air, it is so much better than before. It is still a problem after the engine is off for a while and the heat gets to "soak" into everything, like when it is off to refuel and started again. I drove it today and the vapor lock is almost completely gone. I decided to put heat shielding on the 40" of fuel line prior to the fuel pump too based on your comments. That way you will be forced to have a fuel pump back at or inside the tank. I'll update this thread with more results as I drive it more. Not sure what can be done about the fuel once it is in the carburetor though. I'm just trying to delay the heat getting to the cool fuel from the tank with these shielding options. Test drives today have been promising! It isn't hot enough for a real test yet. Last night I made a fuel filter wrap using layers of aluminum foil and some greenish bamboo fabric I had laying around. The fuel filter area was still directly exposed to engine compartment heat. I added 3' of heat-reflecting sleeve to the engine fuel supply line. Most solutions seem to involve installing electric fuel pumps near the fuel tank. Emotionally, it adds anxiety and reduces driving enjoyment.Īddressing vapor lock while trying to maintain originality is a challenge. Realistically, vapor lock just turns me into the jerk who doesn't know how to get up to speed and holds up the line of cars behind me. The stalling eventually subsides after 15-20 seconds and the engine pulls hard again. The severity of the stalling is directly related to the length of time the car sat idling before moving.ĥ. The Buick will get through the intersection and up to 30 mph before stalling out. Pulling away from the stoplight in #3 is where the problem shows itself. Sitting at a stoplight for 3 minutes or more isn't an issue.Ĥ. Short stops, like stop signs, also don't affect the car.ģ. The car runs well when moving 30+ mph in general and temp gauge always stays in happy place.Ģ. I'm sure it exhibits itself in different ways for different cars. It didn't take long for vapor lock to show itself during my test drives. I first noticed the potential for vapor lock after installing the glass bowl fuel filter and watching it seemingly half-filled while the engine was idling on a warm day. Living at 6,000' elevation (lower boiling point), using modern premium fuel, and driving in 90+ degree heat is the perfect combo for vapor lock.
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