"havses@hotmail.com" <georgehav@gmail.com> wrote
> My 1993 Civic has new-onset failure to start. The problem
> has occurred
> sporadically and only on very hot days. A friend swears
> it's vapor
> lock; previous posts to this group indicate that vapor
> lock is very
> unlikely and suggests a main relay problem.
>
> * *{Additonal data:
> Several times the problem was solved by waiting til the
> next morning
> and trying again.
> Two other times we've put STP Gas Treatment in the tank
> and the car
> started up immediately.
> The problem never occurred until this year. The first time
> the car
> wouldn't start, the positive battery terminal was
> severely corroded.
> Cleaning it did not start the car. The car started right
> up when the
> mechanic checked it hours later. He noted that, unrelated,
> the head
> gasket needed to be replaced, and he did that.}
>
>
> My questions: if it were a main relay, why would the
> problem only occur
> on scorching hot days?

The high heat expands the solder joints inside the main
relay. The joints fail, meaning they won't conduct
electricity.


> In any case, why would such a problem have
> sudden onset? (I'm the original owner and this has never
> happened
> before this year.) Could it have anything to do with
> ethanol
> supplemented gasoline?

No. The main relay problem is strictly an electrical
problem, insofar as car systems are concerned.

http://www.tegger.com/hondafaq/start...html#mainrelay
has a discussion on the main relay. Note the suggestion
(among others) to smack the dash to help identify whether
the main relay is the problem.

If it's never been replaced or repaired before, it's a very
strong candidate for your problem.

Many mechanics do not know about it. Honda owners do.