Vapor Lock after 30 min sit in warm weather

I’ll check and see what it looks like. :ok_hand:

This has all been very educational. (Many thanks to all contributors on this thread!)

I didn’t know anything about Vapor Lock, before and it got me to wondering about the term “engine flooding,” which I’ve heard about all my life, but never really understood. So, I looked it up.

Long story, short, based on this Wikipedia article, it sounds like Moss is describing a flooded engine.

Again, I’m learning a lot today! :grinning:

- Tom -

This is not a vapor lock problem but an over rich mixture after heat soak. The “low boilers” come out of the gasoline, flood the intake manifold and cause the mixture to be too rich. Flooring the accelerator and not using a choke while cranking is the best way to get it started. My tractor does this routinely. Running rich needles makes this problem worse. Check the float level by looking down the Jets. Lowering the float level may help.

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“Flooding” is the result of a massively over-rich mixture. It can be caused by a stuck float valve, blocked air bleed, stuck choke, just plain lousy tuning, or anything else that puts too much fuel into the engine. The excess fuel makes the mixture too rich to light, and/or wet fouls the spark plug. On an engine where the carb CAN get hot enough to “boil” the fuel in the bowl, it is possible for fuel to be pushed out the jet into the carb throat, and cause flooding. But in most cases, even if it does happen, it won’t be enough fuel to cause a problem. And it has nothing to do with vapor lock.

As Mike pointed out, vapor lock occurs on the suction side of the fuel pump. It was a common problem in the decades before electric fuel pumps, when nearly all Detroit cars, and many imports, had mechanical, engine-driven fuel pumps. But in the decades since fuel injection became the norm, it is almost unheard of.

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Interesting. That sounds very much like what may be happening. I remember occasionally getting a wiff of fuel smell during yesterday’s cranking exercise… I’ll ck the levels.

Pull a dome after you stop. If it’s flooded or boiling, you’ll see it in the jet.

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I had a problem like this - it was flooding from a float that was starting to have problems. Perhaps there was enough variation in the new needles or you didn’t get them positioned properly and it’s enough to cause flooding when hot.

You got lots of ideas here
Do some test and eliminate some for the record I don’t think it’s vapour lock simply because the fuel pump is in cold fuel at the back
Next time it does it shoot some ether in it, if it doesn’t start and it won’t you no it’s electric
Now when it’s cold take a heat gun and warm some things that are common like the coil maybe mount the coil low out of the heat temporarily or cool it when hot with ice
Cheers

My 1930 Ford Model A had the same problem. Found the car was too rich to fire up after heat soak of a few minutes. Ether spray would not light the engine either in that circumstance until enough air had been drawn through engine to get rid of too-rich condition. This car has no fuel pump and is gravity fed, found that shutting off the fuel flow before shutdown and letting the engine run until starved off solved the problem. The engine can be fired right up at any point after hot shutdown now (provided fuel valve reopened) and no ether required.

On the old Jags I’ve found the circumstance could also be due to bad rotor or bad distributor cap either of which can become non-performers in heat soak condition. Quality of parts varies. Others have reported coil problems and if the condenser is not functioning that can make it all worse.

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Plus 1 on it being an overly rich condition on hot shutdown as opposed to lean.

While less common on cars, it happens a lot on the aviation side in the summer. I’ve had to rescue more than a few experienced pilots who couldn’t get their engines to start after hot shutdown.

How old is your coil? Had similar problem, it was igniti OK n rekated.

You say you removed the ballast…did you switch to a 3 ohm coil? If not, give that a shot.

No a replaced the ballast as in got a new one. As well as a new coil. Lots of things to experiment with…

Just so I keep the potential issues straight. Vapor lock probably isn’t the issue so on to ck possible reasons for rich condition or electrical factors. Wont be driving her that hard for a while but I’ll report back in a couple weeks

  1. Float could be having an issue
  2. Float level could be off
  • pull dome to visually check for flooding
  • Check plug condition ie. wet
  1. Coil could be overheating (it’s 5 yrs old)
  • Apply cold to coil to see if it responds (or just swap with another one)
  1. No condenser as its a 123 Dist

After testing in several different situations I’ve come to the conclusion that this is/was a heat soak rich condition. After running the car hard on back roads and parking it in the sun with no breeze, the condition can be duplicated. This condition cannot be duplicated if the car is simply driven in traffic, it has to be driven aggressively. It occurs if the car is left for 15 to 40 minutes. It starts fine if it’s left for just a few minutes when there’s not enough time for the heat soaking to occur. If it’s left for over 90 minutes, there is also no problem restarting the car. The ambient temps have to be warm also. If it’s cool out the issue is hard to duplicate.

The condition can be eliminated by cracking the bonnet a few inches and parking the car pointing into any breeze to get air flow through the engine compartment.

On my S2 I moved the power feed for the electric fan from fuse 6 to fuse 4. Going from a green wire circuit (controlled by ignition switch) to a brown wire circuit (always hot) means that the fan will continue to cycle after shut-down until the coolant at the otter switch has cooled some.

Not everyone agrees this is a useful modification but I find it helpful as I take long trips that include 15 minute stops for fuel throughout the day.

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Mine used to sometimes not want to start after eat soaking after a brief stop. I did what Geo did with the addition of a relay that allows the fans to run a maximum of 6 minutes after I shut off the engine.

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Most if not all modern cars have fans that will run after shutdown. What did you use for the 6 minute max timer?

Similar to this, IIRC.

Amazon.com: HELLA 996152131 12V Delay-On-Release, Time Delay Relay, Black : Automotive

Would you replace the original relay with this or add it to the original relay circuit?