After a 50-mile run I experienced very strong backfiring when going
forward at stoplights- plus loss of power. The backfiring cleared up
after I could reach cruise speed at 3,000 rpm, but got even stronger
from stoplight to stoplight. Engine runs great when cold. Carb
pistons topped up with carb oil. The three SUs seem to be in synch.
Choke checks out O.K. Stored car in unheated garage last winter and
added Stabil to gas tank. Could I have water in the gas tank?
Also, after engine shutoff with temp gauge reading 80C, I have
trouble restarting as cooling fan seems to be drawing too much power
from battery so starter barely turns over the engine. Battery checks
out at 14.5 amps after full charge. Can a battery on the skids still
show full charge, but is not able to maintain full charge power?
All this puts a damper on using my 64 3.8L FHC for any long trips
that require any stops along the way.
Bob 1964 Series 1 3.8L FHC
Hi Bob,
I have a '64 FHC also. If my car were doing this, here’s what I’d do:
Remove plugs; clean, gap or replace: NGK BPR5ES
Check spark plug wires for arcing; replace as necessary
Check points (condition and gap) and condenser; replace if necessary
(especially condenser)
Check distr rotor; replace if necessary
Check distr cap (cracks, chips, arcing inside); replace as necessary
Check static timing set at no more than 10 deg BTDC
Check coil (when warm)
Check carb “mixture” (could be too lean)
Check all butterflies opening “at the same time”
Check float levels are correct
Check aircleaner; replace element as necessary
Check all vacuum lines are tight and not leaking
Tighten up all manifold bolts and nuts
Check the condition of battery terminals; clean as necessary then
tighten
How old is the battery? It could have a cell going bad that looks good
on a surface charge. Suggest having it load checked.
If none of the above worked, I’d do a compression check. All s/b be with
a few psi of each other…180psi optimum.
Cheers,
Chuck Anderson
'64 FHC
890250
“Robert J. Richardson” wrote:> After a 50-mile run I experienced very strong backfiring when going
forward at stoplights- plus loss of power. The backfiring cleared up
after I could reach cruise speed at 3,000 rpm, but got even stronger
from stoplight to stoplight. Engine runs great when cold. Carb
pistons topped up with carb oil. The three SUs seem to be in synch.
Choke checks out O.K. Stored car in unheated garage last winter and
added Stabil to gas tank. Could I have water in the gas tank?
Also, after engine shutoff with temp gauge reading 80C, I have
trouble restarting as cooling fan seems to be drawing too much power
from battery so starter barely turns over the engine. Battery checks
out at 14.5 amps after full charge. Can a battery on the skids still
show full charge, but is not able to maintain full charge power?
All this puts a damper on using my 64 3.8L FHC for any long trips
that require any stops along the way.
Bob 1964 Series 1 3.8L FHC
Bob-
Experiences with my '68 FHC and '73 TR6 have lead me to check the
ignition system first since they are typically the weakest link in the
chain. My FHC idled too fast and wandered, was hard to start, timing was
never quite right, real uneven exhaust note, and always overheated. The
cause? Bad distributor. I replaced it with a dual point Mallory and
solved all those problems at once - sometimes I just start it up to just
listen because it sounds so sweet now =)
In my recently acquired '73 TR6, it idled rough, backfired, timing was
off, didn’t start as easy as it should, and hesitated from a dead stop.
It ended up being a bad vacuum advance unit on the distributor (these
are very easy to check). It also broke down on me on the highway after
less than 24 hours of ownership - the rotor in the distributor had
cracked and the metal contact came loose chewing up the inside of the
cap. A new cap and rotor got it running again. I carry a spare rotor and
cap in the boot now.
So, if it were me, I’d be looking at the distributor and supporting
ignition components first. They’re pretty easy to diagnos and not very
expensive to fix.
To check to see if the vacuum advance is functioning properly (if you
have one), remove the distributor cap and attach a piece of tubing to
the advance nipple and pull a vacuum with your mouth on the other end.
If you just get air or a weak vacuum, it will need replacing. If not and
it moves freely its probably OK and start checking out the rest of the
ignition components starting with the rotor/points/condensor and then
the coil.
-Tim Speck
'68 FHC E-type, '73 TR6, '84 SVO
“Tongue tied twisted just
an earthbound Misfit, I”
-Pink Floyd-----Original Message-----
From: owner-e-type@jag-lovers.org [mailto:owner-e-type@jag-lovers.org]
On Behalf Of Robert J. Richardson
Sent: Thursday, August 01, 2002 11:04 AM
To: e-type@jag-lovers.org
Subject: [E-Type] Backfiring, loss of power
After a 50-mile run I experienced very strong backfiring when going
forward at stoplights- plus loss of power. The backfiring cleared up
after I could reach cruise speed at 3,000 rpm, but got even stronger
from stoplight to stoplight. Engine runs great when cold. Carb
pistons topped up with carb oil. The three SUs seem to be in synch.
Choke checks out O.K. Stored car in unheated garage last winter and
added Stabil to gas tank. Could I have water in the gas tank? Also,
after engine shutoff with temp gauge reading 80C, I have
trouble restarting as cooling fan seems to be drawing too much power
from battery so starter barely turns over the engine. Battery checks
out at 14.5 amps after full charge. Can a battery on the skids still
show full charge, but is not able to maintain full charge power? All
this puts a damper on using my 64 3.8L FHC for any long trips
that require any stops along the way.
Bob 1964 Series 1 3.8L FHC
Backfiring when hot sounds like a bad coil or condenser. Bad gas would
probably work equally poorly at all temperatures.
To test a battery, measure the voltage under load, not after a full charge.
With the engine off turn the headlights on and watch the voltage reading.
It should stabilize at around 12.5 volts. My guess is it will quickly drift
down to around 10 volts, indicating a shorted cell.
Mike Eck
New Jersey, USA
'51 XK120 OTS
'62 3.8 MK2 MOD
'72 SIII E-Type 2+2----- Original Message -----
From: “Robert J. Richardson” rrichard@frognet.net
To: e-type@jag-lovers.org
Sent: Thursday, August 01, 2002 1:04 PM
Subject: [E-Type] Backfiring, loss of power
After a 50-mile run I experienced very strong backfiring when going
forward at stoplights- plus loss of power. The backfiring cleared up
after I could reach cruise speed at 3,000 rpm, but got even stronger
from stoplight to stoplight. Engine runs great when cold. Carb
pistons topped up with carb oil. The three SUs seem to be in synch.
Choke checks out O.K. Stored car in unheated garage last winter and
added Stabil to gas tank. Could I have water in the gas tank?
Also, after engine shutoff with temp gauge reading 80C, I have
trouble restarting as cooling fan seems to be drawing too much power
from battery so starter barely turns over the engine. Battery checks
out at 14.5 amps after full charge. Can a battery on the skids still
show full charge, but is not able to maintain full charge power?
All this puts a damper on using my 64 3.8L FHC for any long trips
that require any stops along the way.
Bob 1964 Series 1 3.8L FHC
How do you check the coil?
At 10:36 AM 8/1/2002 -0700, you wrote:
Hi Bob,
I have a '64 FHC also. If my car were doing this, here’s what I’d do:
Check coil (when warm)
66 S1 OTS
e mail @Bill-B
In a message dated 8/2/02 4:10:54 PM Pacific Daylight Time, etype66s1@cox.net
writes:
<< How do you check the coil? >>
Bill,
If its a recent manufactiure, remove it from the car and shake it. If it
"sloshes " or is oily , its probably bad. Otherwise, what I do which isn’t
real scientific, but has worked well is this:
Get any good spark plug. Make sure its clean a reasonably well gapped. Use
one jumper cable lead and clamp one end to the base of the plug, the other
end to ground. Put any plug cap on the spark plug. Start the engine (or try
to) and watch for the color of the spark.
Blue-white- very best
white-yellow-good
red-bad
Good Luck, Mike Moore
There are resistance values (ohms) and current draw (amps) that are
specified for coils and will indicate it’s health… measuring from contact
to contact, and from each contact to the high tension output… I don’t
remember what those values are supposed to be (it’s only been 20 years)…
there would be specific values for different coils, but I believe the values
should be pretty similar for most coils. If the coil is bad the values will
be not just a little off, they will be way off.
Unfortunately, the Bentley and Haynes books do not show specs for testing
coils.
I do have a book that lists values for some cars, but not Jaguar. As an
example, the primary winding resistance for all 1978 Triumphs is 1.80-1.45
ohms. If I remember correctly, resistance between the primary and secondary
windings should be infinite. I checked an old - but known to be good - Volvo
coil: It had 2 ohms across the primary circuit, and infinite resistance
between primary and secondary.
Some coils are oil filled, some are tar filled. Shaking is probably not an
indication of health. Leaking is bad, though. I have also seen the results
of a coil exploding. Messy, and probably caused by leaving the key on…
Disconnecting the high tension lead and cranking the engine without
grounding the lead will almost certainly short some of the secondary
windings and decrease maximum spark voltage. Always ground the lead, or
disconnect the power wire to the coil before crank tests.
I used to know a guy that sold testing equipment… he would pull a spark
plug wire of of a running engine and hold it in his hand… he then would
put his finger to ground and show the customers what 20,000 volts going
through a human body looks like on the oscilloscope… didn’t bother him a
bit.
The spark color test is useful. It will give you a feel for the output of
the whole system… the spark will be affected by battery voltage, coil,
cap, rotor, points, wires, wiring, etc… I took a new spark plug and brazed
a spring clamp to it for just that purpose… it’s a great starting place…
of course nothing takes the place of an oscilloscope for checking the entire
system…
–Harold
Harold Robertson
Redding, California, USA
1968 E-type 2+2 (unrestored driver) 1E78833BW
1971 Volvo 1800e (unrestored driver)
1986 Nissan 300zxt (turbo)
http://home.pacbell.net/p1800guy/
Bill,
The other suggestions here are good but I’ve always tried to borrow one
and if I couldn’t do that I bit the bullet and bought one. Less than
$20 and not a bad thing to have as a spare if it’s not the trouble.
pauls 67ots
How do you check the coil?
<<<<<<<<<<From: Bill Bilotti etype66s1@cox.net
Subject: How? Re: [E-Type] Backfiring, loss of power
At 07:18 AM 8/4/2002 -0400, you wrote:
Bill,
The other suggestions here are good but I’ve always tried to borrow one
and if I couldn’t do that I bit the bullet and bought one. Less than
$20 and not a bad thing to have as a spare if it’s not the trouble.
pauls 67ots
That was always my approach… and the only one ever suggested to me until
this thread so I thought the procedure would be a good thing to know. 
Bill
From: Bill Bilotti <@Bill-B>
Subject: How? Re: [E-Type] Backfiring, loss of powerHow do you check the coil?
<<<<<<<<<<
66 S1 OTS
e mail @Bill-B