Series 2 weak spark

Hi All,

Over the past few months, my series 2 E type has had intermittent misfiring issues with running. The car was off the road for 8 years and was back on the road a year ago. I had SU carburettor issues sucking air from areas they shouldn’t so I rebuilt them. I’ve replaced spark plug leads, coil, condenser and the issues seem to improve initially then develop again and worsen. Today, I drove approx 60kms on a motorway at 100kph and it developed a misfire. I got almost all the way home before it died and I had to have it towed home.
Once home, it wouldn’t start or run so I checked and found the spark from the coil is very weak. I disconnected the spark plug leads and plugged a spark plug in the ends and the spark is very weak.
The coil, spark plug leads and condenser were all replaced a month ago. The points look fine and are not burnt out. I don’t have a ballast ignition. It is the standard Lucas distributor.
What are your thoughts? I am totally stumped and the bloody car is stuck in my driveway because my garage is at the top of my steep driveway.
Thanks in advance for all your help.

Jerome Brand
Melbourne Australia
1970 2+2 E type

Hard to say but if spark is weak, I would check that you do have 12V at the coil with ignition on and 12 v with engine running. ie there is no drop between battery and the coil. Then check that all connections are good. Then I would suggest to replace rotor and distributor cap

Dennis 69 OTS

Yes you might check the rotor. Not long ago I had a no start or hard start problem after running for awhile. I found the arm on the rotor to be slightly loose and able to move around some on the plastic piece. I put a old used rotor in and it fired right up. I have read on here about some bad batches of rotors.

68 E-type FHC

A problem I had which you might check for is crossfire.

If you are using the cardboard tube to bundle the wires you can get a pair that end up exchanging spark.

An easy test is to use a strobe timing light and look at the timing mark while connected to each of 2 through 5. You shouldn’t see the mark (for 1 & 6) light up but if you do that is a misfire.

many places to look/check…as others have listed…some rotors have been poor…easy replace with newer–red one, possible space in wire ends…when pushed on (within the wire to wire terminal…so electricity has a " gap" within the wire to terminal end to jump., and…but you say you replaced primary spark plug wires…these should be quite low resistance wires…actually zero is best…but low per foot of wire. Most modern wire kits are for new cars and have VERY hi suppression (resistance). May have been hi suppression prior…and now even higher. try ohmmeter test, …or a simple small 1.5v continuity tester…see if the tester will lite up on the longest plug wire… Nick

Did you fit new Champion plug caps? They are known to be faulty.

Could be carbon tracking inside the cap, a bad rotor, or a non-conductive film on the points. Power for the ignition system comes THROUGH the tachometer, so you may want to reseat the connector the the tach. But you didn’t say you replaced the cap, so that’s where I’d look first. I’d also replace the condenser again before going further, as a lot of these are bad out of the box.

Jerome, I have trouble following the sequence. You initially had a misfire, replace all the ignition, and now it is worse. My problem is to wonder if you initially had a weak spark, or you ended up with a weak spark after replacing the ignition? Or if you do not have an ignition problem at all. But based on you saying you have a weak spark, my thoughts: double check the dwell and timing to see if something slipped. If not, any replacement part could be suspect, so, as others said, visually check cap, rotor, see what you can on the plug wires/ends, but in my experience, the most likely new part to fail quickly is a condenser, and that will cause just about any type of ignition symptom in the book.