[Mgs] No Go Mystery

Wed May 4 09:05:52 MDT 2016

To add what a few others have mentioned, it does sound electrical. The first
thing I do is determine whether its electrical or fuel. With fuel in the
bowls, it tends to point to electrical although I also check the carb
dampers and that the pistons can move up and down (not stuck). On the
electrical side, I pull out a spark plug to check appearance and then with
it connected to the ignition lead, place it on the block and check for a
visible spark when cranking the engine.

Now to add to this, a short story on my last issue of this nature - I was
having some intermittent and very short durations of power loss when I
started driving my 64B this spring which I at first thought might be
moisture in the fuel.until it completely died on the drive home one day
(after I ignored the problem for several days). I coasted into a nearby
Wendys parking lot and determined there was no spark so I started checking
connections, particularly the condenser to points connection (insure
tightness, proper insulation with the plastic washer). Turns out the nut was
slightly loose so I tightened it. Car started right up and I drove home. But
the intermittent cutting out started to return again (maybe a few 1-2 second
incidents over several miles). So I decided to replace the points and
condenser the next weekend and that was when I discovered the real problem.
On the points terminal that the condenser attaches to, there is another
cloth insulated wire that attached to a plastic terminal on the distributer
(part #16 -
http://www.mossmotors.com/Shop/ViewProducts.aspx?PlateIndexID=29062 ). The
wire had started rotting away to the point that it was down to a few copper
strands (but unseen inside the cloth insulation)and it disintegrated during
the points removal. Fortunately, I had a spare distributer that I could get
a replacement part off and that solved the issue. Car has been running great
now with about 500 miles or so of error free operation.

Other suspects would be the condenser or possible the ignition coil - I have
had these fail in the past. And as far as cam flat spots - I have had that
issue too about 30 years ago. However, that did not stop the car from
running - it just idled rough and suffered a lack of power (but not a loss
of power). You would know when doing the routine valve adjustments as you
will not see much up/down movement of the valves.

David Councill

64 MGB

67 MGBGT

72 MGB

From: Mgs [mailto:mgs-bounces at autox.team.net] On Behalf Of Robert J.
Guinness via Mgs
Sent: Tuesday, May 03, 2016 12:10 PM
To: MG List
Subject: [Mgs] No Go Mystery

While on a long drive in the hinterlands of KY in my 1960 MGA with a 3-main
1800 MGB engine, I nearly ran out of gas after about 170 miles that day.  I
found a gas station and refueled (the gas had alcohol and I usually run
non-alcohol gas).  About 30 miles later, the car started to lose power and
then quit. Figured it was a clogged fuel line, but fuel was pumping out of
the fuel line at the rear carb and there was gas in both float bowls.
Cleaned out both float bowls.  Had spark from the coil and to all plugs.
Had just replaced spark plugs and gapped them to spec two days previously.
Regapped points (1 year old 25D distributor). Nothing.  Sprayed starting
fluid in the carbs.  Nothing. Locals towed me back to town. Locals played
with wires under the bonnet at the coil as I politely batted them away.  As
a last ditch effort, I advanced the timing and it caught at high revs!
Drove a few miles, but lost power as I accelerated and stopped.  Stripped
and reattached coil wire to harness.  Started, drove a couple of miles,
faded, and stopped. Towed it home.  At home, it started reluctantly.  It
drove for a couple of miles and it faded and quit. Gas  in rear carb float
bowl but no gas at the front carb float bowl. Blew air from fuel pump back
to gas tank with audible air flow at the gas tank.  Replaced the float bowl
needle and seat at the front carb.  Fuel pumping nicely at both front and
rear carbs.  Have spark from the coil and to all plugs. Static timed.
Nothing, doesn't even try to catch. I do not have a fuel filter other than
stock sleeve in the fuel pump. No odd sounds. I am stupefied ( except for
the possibility of clogged jets, but if so why wouldn't it start with
starter fluid).  If it is the coil or condensor, why am I getting spark?
Why would advancing the timing get it to go at such high revs that one time,
but normal timing gives you nothing at all, not even a spit? Do I have a cam
flat spot problem? How have I angered the British engineering gods?  Any
hints or diagnostic suggestions?

-- 

Robert Guinness

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