Honda Civic 1993 - intermittent failure to start

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? 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? Thanks

 

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

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

http://www.tegger.com/hondafaq/startproblems.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.

 

Very odd, that, isn't it?

Something less than half the email I get has to do with the single problem
of the Main Relay. It is easily the #1 Honda problem, far outstripping any
other single issue. And yet almost none of the pros are even vaguely aware
of it.

 

See Elle's response. It's your PGM-FI Main Relay.

 

actually, if you're used honda scuzzbag like me, this is a great thing.
it means you can buy non-functioning hondas for almost nothing and
drive around in a virtually free car. or give them to friends. feel
the love, man!

 

Yes. I think it's quite an argument for the value of
amateurs posting their experiences to internet fora like
this. The database is enormous and often is scientifically
significant.

This data point in itself is important.

Aside: I was just reading your PCV site. I have long
wondered how your 91 Integra's PCV valve stayed pristinely
clean for over 200k miles while my 91 Civic's was "chock
full of waxy buildup" at about 140k miles. This is despite
my frequent (every 6 mos/3k miles for many years, followed
by 6 mos/5k miles more recently) oil changes since buying
the car new in 1991.

Last winter I found my PCV valve had way more waxy specks
than usual following the use of STP fuel system cleaner. I
hardly ever get the specks with Chevron Techron fuel system
cleaner. You say you have used only Chevron gas, known to
have cleaners in it. I have always used whatever gas was
cheapest. I wonder if this explains the difference between
your and my differing PCV valve experiences.

Just thought I'd toss that in there for the weekend car talk
series.

 

LOL

 

I'm kind of curious where you found that. Chevron does not have retail
outlets in Canada. Nor does it sell its Techron additive in stores up here
(tho' I wish it did...).

I've used Imperial Oil (Exxon) almost 100% over the last 15.5 years. In
Ontario, Canada, that means the old eastern-US "ESSO" brand, by which name
the retail stores are still known up here. I use ESSO because they are the
last major up here to not use ethanol.

(As an aside, ESSO originally stood for "Eastern Seaboard Standard Oil".
Nobody knows that these days...)

Your situation is most intriguing. I wish I could see your car personally.
I've seen sludgy buildup many times, but never the waxy stuff you describe.

 

I had been filling up at Sunoco for the last 3 years, and only recently I
noticed on one pump that their gas had some amount of ethanol in it (I
forget the actual percentage, but I think it was 10%). Not to defend the
use of ethanol, but so far my '93 Accord's performance and gas mileage have
not suffered as a result of using Sunoco gas (I still average 33mpg on the
highway, which is well above EPA's original estimate). Perhaps I should try
Esso again to see if slight improvements in both can still be achieved.

 

Interesting about the Esso brand because I have a nice lighted oval
shaped Esso sign hanging in my basement that was trashed when they were
swapping all the Esso signs around here to Exxon. I figured it was a bit
of a treasure by now because they had been gone so long. Well, it still
makes a nice light!

 

Obviously I misremembered/confused your post with someone
else's. I groups.googled and see your post from a few years
ago where you say you use the Esso (premium in the summer).

There is also no question you have been more meticulous
about your 91 Integra's upkeep than I have with my 91
Civic's. I suppose it's either this or the gasoline or some
combination that have yielded your car's PCV valve staying
so clean. But I really don't know.

I just "discovered" a better junkyard in my area; carefully
organized but customers have the run of the place for a
dollar admission charge. It has several c. 1990 Civics and
Integra. Next trip, maybe I'll pull off a few PCV valves,
noting the mileage of the cars, and see if anything
interesting is revealed.

It was only evident in my Civic's PCV valve in 2003. The new
PCV valve has stayed very clean, excepting my experience
with the STP fuel system cleaner.

I have been under the valve cover several times since
(checking valve lash, replacing the gasket, replacing those
spark plug tube oil seals between cylinder head and rocker
arm), and the rocker arms, tower, etc. look not spanking
clean, but certainly nothing like a sludged engine.

My manual transmissions instructor totally dissed my use of
Pennzoil (exclusively) the other week. Maybe it's a bad
choice. I am not inclined to switch, though, since I have
never seen a consensus against it.

Let me cease to be a hijacker and return this thread to its
original programming.

 

Do a search on the main relay and you will see lots of comments about
temperature. Hot days really brings the problem on. Good luck.