Vapour Lock.

[Paul TullettParticipant]

Hello, I haven’t used this forum before, so here goes. I have a ’54 light fifteen which, since it’s complete restoration about 6 years ago has done about 3000 miles. Over that time it has driven well and I have had no problems. Last spring (2020) I experienced problems with what I assumed to be vapour lock when, having driven for half an hour or so, then stopping and restarting with a warm engine, the engine cuts out and fails to start again until cool again. I looked at some possible solutions and found that moving the filter between pump and carb helped. Now, having bought the car out of its winter hibernation this year I am experiencing the same problems. I suspect this may be a common problem having read somewhere about it before. Can anyone offer advice on what could be causing the problem and how it could be solved?

[Richard OliverParticipant]

The symptoms of “vapour lock” can sometimes be similar to those experienced when the ignition coil starts to fail insofar as the engine seems to run fine until it is switched off and allowed to stand, then fails to restart until the engine and its components have cooled down. That would be the first thing I will look at, particularly if, as you say, it used to run without this problem. If it were vapour lock, I would have expected it to have been a regular feature rather than a recently developed one.

[BernieParticipant]

Paul,

It is true that vapour-lock can sometimes be a problem with these engines.  However, I believe you are UK based and,   bearing in mind the current ambient temperatures here,  I would be extremely surprised if that is the cause of your problem today ……. it normally only manifests itself on the hottest of “summer” days.

B…..

[Paul TullettParticipant]

Thanks for replies so far. Now it has been mentioned I fitted a new coil about 2 years ago, before this started to happen. It could be faulty – is there any way of finding out? I have driven the car successfully over the past few days (to get the engine hot) and not had the problem re-occur. I’ll find a spare coil in the meantime and keep it in the boot in case it happens again.

[189Participant]

When I had the same problem a couple of years ago it turned out to be a cracked rotor arm.

[Larry LewisParticipant]

It could also be a cracked distributor cap. I had that happen, loud backfiring, brown smoke blowing out of the air breather. I thought it was the coil, but the cap was cracked. I did have vapour lock about 15 years ago when I drove the 11B to a car show in Michigan. It was over 100 degrees farenheit for the entire weekend and it was hard to start when the engine was hot. I didn’t do anything to the engine and haven’t experienced it since.  But do check the cap.

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