Quote:
Originally Posted by Formulajones
I'm sure you could come up with all kinds of ways to test. I did it this way for a couple reasons. 1, I'm not spending a bunch of my time on a silly subject that honestly is simply just a non issue. 2, that was meant to show the few in here that fuel simply does not disappear into thin air by itself very easily like some eluded to without some sort of excessive heat source, or a leak somewhere. Notice I didn't just give it a tiny vent hole either, I left the lid off of a jar LOL
You guys can go on thinking 4-5 seconds is excessive cranking after a car has sat for weeks and put your pusher pumps on if you wish, I'm not here to tell you otherwise, but there is nothing abnormal about that. These cars were the same way when new. EFI has spoiled the masses. In fact some EFI tunes actually crank for several seconds before they hit just in case you weren't aware. That's the starters job and they are cheap and easy to replace. If you're burning starters up you got other problems.
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Was just a general comment or suggestion that the test wasnt the same environment as fuel in a hot engines carb so therefore didnt represent whats happening in that situation. I understand not spending a bunch of time on something you find silly, just saying that test is nothing like what happens on a car.
2, gas does evaporate, into thin air, and can happen faster than a big jar full sitting at room temp, it doesnt require "excessive heat", 160-190° of normal engine temps with a thimble full of fuel can & will evaporate in a relatively short period of time, maybe not a couple hours but 24-48-72 hours would likely be different... add to that possible drain back and this type of hard starting is definitely an issue for many people, Ive read quite a few threads on it over the years.
I am not a "you guys", Ive been dealing with occasional fuel evap or whatever it is in 2 of my q jet cars for a long time, both carbs were built by Cliff so I doubt there is any leaky well plugs. Also for whatever reason my other car with an 81 CCC Q-jet does not do this at all, it can sit in the same garage & same temps for 2-3+ weeks & start after just one short 3-4 sec crank... but the other 2 cars for whatever reason require 2-3 short cranks to get fuel into the carb after sitting for about 4-5 days, not really an issue to do that IMO.
I can say in my experience that these cars did not do that when new or nowhere near as bad, some say the fuel was a lot better back then too so it shouldnt have been as much of a problem. Just like my 81 CCC Q-jet, Ive owned or known of other q-jet cars back in the 80s-90s that didnt do this, they would usually start in ~5 seconds of cranking the starter after sitting for a couple weeks.
Just adding my experiences owning a few Q-jet cars for 25+ years, and that an experiment test closer to the real world situation of a hot carb would have better shown what happens with a small amount of fuel... just like most other things on here, everyone has different experiences. Heres just 1 link about fuel evap that supports it does evaporate and heat effects it.
https://ranwhenparked.net/does-gasoline-evaporate/