I'm Stumped...No Spark

I had two starts that had a long cranking. On the third start (at the gas station after filling up) she would not start. Towed home.

Sprayed started fluid into carbs No start, not even a stumble. Pulled a spark plug wire and held near block. no spark. Pulled HT lead from dizzy. Had a yellow sparking.

I have cleaned the ground strap from the engine to body.
Not owning the car long or knowing it’s history I then replaced the spark plugs, spark plug wires, dizzy (PerTronix Ignitor II) the coil (Pertronix Flamethrower recommended by Pretronix for the dizzy I bought) and cleaned the block where the dizzy makes contact.

I have 12 volts at coil + and engine turns over smartly.

Still not starting.

Thoughts, ideas.

Jeff H.

This is a '71? Did it have Pertronix when you got no spark at the plugs but a yellow spark at the dizzy? Is the power wire (red?) to the Pertronix hooked up?

Also, on the S1 cars there was a ballast resistor and a provision (from the starting relay) to bypass the resistor when starting. This circuitry, if connected incorrectly, can be problematic.

There is on line info available showing how to test the Ignitor II independently–might try that.

I had some difficulty starting my '72 - would fire during cranking and die when the starter withdrew.
I would try car with the ballast out of circuit so that the car cranks and runs (if it runs) at 12v to the coil and see if that works. Indicative of relay/ballast problem. You won’t do any harm running this way whilst diagnosing. Paul.

Hi Robert,
It’s a 72. No, the Pertronix was added after the spark testing. Yes, the power wires to the Pertronix are hooked up The ballast resistor has been removed following Pertronix instructions. I guess I naively thought replacing everything would solve the problem, but it was a to-do on my restoration list anyway.

I am unable to do any testing this weekend (Sunday /Monday is my weekend) as we are sadly having a snowstorm in NW Iowa today and the car is outside until next weekend. Don’t ask. :scream:

Jeff H

Hi Paul,

Ballast is out of circuit now. Still no start. I did try running a wire from battery + to coil +, still no start.

Jeff H.

it can only be a very limited number of items

I prefer a full points dizzy for diagnosis

presumably there is a way of testing the Pertronix with a multimeter to indicate if it is the failed component, check Google to do that

Brrr, Jeff…:slight_smile:

First test; connect a test lamp between coil neg and ground. Ign ‘on’; lamp fully lit - ign ‘crank’; lamp should dim and flicker. If not; verify that the Pertronix is connected to manufacturers spec. Particularly the coil pos and neg wires…

If test lamp behaves as it should and with a weak spark with coil center lead - consider replacing the coil center lead. With the Pertronix working as it should; it should give half an inch of spark from the coil - with ease.

Replacing the distributor and plug leads require great care to preserve the correct ignition sequence. Assuming the Pertronix dist is a direct replacement, aligned the same way; each lead should be changed in turn, starting at one end of the engine. If the dist and leads were all disconnected in one go; you have to start ignition sequence from scratch…

Faulty ign sequence will not interfere with spark power, of course - but the engine will misbehave…

xj6 85 Sov Europe (UK/NZ)

Jeff. Do you have a shiny black ignition rotor with a brass rivet that doesn’t say Lucas? If so those things are cheap chinese plastic that can and eventually will leave you stranded mysteriously with no explanation. What happens is the plastic is a poor insulator and eventually the high tension spark will find a path through and ground out. Also the rivet is another failure point because it’s too long.

This has been a problem for years with British cars and it really sounds like you are having that issue. It will sometimes show an arc but more often than not the rotor looks perfect. They still sell this garbage so it’s possible that even if new you could have one. Worth a look. There is really no way to test the rotor… If it’s black plastic replace it and if all else is okay the car will start. Even green box Lucas replacements used to have this thing in the box. Recently they wised up and started putting good ones in there.

If you have one of those rotors there a couple manufacturers that make good ones. They are usually red or blue and the contact has no rivet - it is melted on to the plastic.

Also check your rotor button to be sure it’s there and making contact.

I assumed that the Pertronix was delivered complete and brand new, Mike…?

xj6 85 Sov Europe (UK/NZ)

Hi Frank - not necessarily. He didn:t mention how he got it. If it was just the dizzy it’s possible to just transfer the cap and rotor and mysterious problem to the new one. One thing I always check if something strange or mysterious is going on with ignition is the presence of that garbage rotor. I actually just check as a matter of course when I begin to diagnose any unfamiliar car. I always keep a good rotor in the car as well.

Regarding the rotor button. I bought a brand new dizzy that was shipped with the cap on and the rotor button was jammed up into the cap and broken. Not saying any of these things are the issue but a quick visual check sometimes reveals things that shouldn’t be happening but are.


Repeat the HT from Dizzy spark test. Crisp snappy blue is the objective. Any change?


It’s indeed prudent to check everything, Mike - taking anything for granted is risky…:slight_smile:

xj6 85 Sov Europe (UK/NZ)

Thanks for all the good info everyone!! I have the battery on the charger overnight tonight and my Uncle and I will be doing full checks of everything again tomorrow.

Yes, the dizzy was new and complete with new cap and rotor.

I’ll let you know results tomorrow evening.

Jeff H.

Ok all, I know you’ve all been holding your breath. lol

Today, starting at the ignition switch, I went through everything. At each stage, I had voltage, a lighted test lamp or sparking. Good to know my new parts are working. I ended at the spark plug boots sparking to the block. The spark plugs are new and correctly gaped.

The engine turned over really well as usual. It did NOT start. One about the third try my Uncle sprayed started fluid while I turned over the engine. Nothing! Pulled a fuel line at the carbs. Fuel flowing.

Pulled the manual choke out fully and cranked away…long crank…got frustrated and pumped the gas peddle…she came to life and ran for about four seconds then died, not to start again.

So, towed the car over to the garage I’m using for the winter. I work tomorrow, but on Monday I’ll transfer my tools over, and set up for a Zenith Stromberg carb rebuild.

Thoughts / ideas?

Jeff H.

Given that you have a fuel issue, Jeff - attending to the carbs seems a good program…

It’s a bit odd then that the engine didn’t respond to starting fluid - but at that stage (third try), the engine might be ‘all wet’, drowning the spark? That it run only for seconds when it eventually started also implies a fueling issue, implying that it starts on accumulated fuel - but fuel is not continuously supplied…

Tuning the carbs properly requires of course a running engine - but even out of tune the carbs should deliver something. However, what about your cold start aids; what sort of choke set-up do you have…?

It is prudent to have a spare spark plug, triple gapped, for supervising sparking. It can be attached to any plug lead for quickly verifying spark (blue) - without interfering with starting and running.

xj6 85 Sov Europe (UK/NZ)

Just got back to my series 1 after months away due to Covid lockdowns etc. She wont start, SU carbs and standard dizzie setup, Fuel pumps run ok and stops when carbs full so I dont think its a fuel problem, There is a very weak spark with HT output from coil feeding a plug. checks out ok with 12 volts to coil when ignition switched on but I can’t check voltage when i hit the starter because I cant be in two places at once. Engine turns over fine so not battery I don’t think. Have changed condenser to eliminate that. Can I test coil alone by making and breaking 12volts across it with a plug on high tension lead to see if proper spark? Its an early car so doesn’t have ballast resistor I don’t think… Where would it be if it did have one and where is the ignition protection relay hidden?
Anything else I can check? I will try to change rotor arm though it is a good non riveted version and also dizzie cap to see if that makes a difference. Car has the original solenoid enrichment system but its showing no sign whatsoever of starting so I don’t think its that, it was ok when I last ran the car in June.

ANy help appreciated, its raining today and car is outside so will have to wait till tomorrow.



you can easily put two DMM wires to a cigar lighter plug and check voltage during cranking from the driver’s seat - “Electrickery trick” courtesy of Carl Hutchins - extremely helpful! Unfortunately, it will tell you only whether or not the battery is good and/or extraordinary retaining forces have to be overcome during cranking. The functioning of the coil is not indicated. If possible, swap in a known-to-be-good other example.

Good luck


75 XJ6L 4.2 auto (UK spec)

You cannot test the sparking by manual make and break, Ian - the action is not fast enough for effective sparking. As a curio; someone reported successful testing by using a farrier’s coarse file; grounding the file and and stroking the coil ground wire along it - never tried it myself…:slight_smile:

Have you actually checked/cleaned/gapped the points?

All points equipped cars had a ballast resistor set-up; bypassed during cranking for max spark voltage - and in line with the engine running. Basically, a ‘6V’ coil was used; with a bypassed resistor ‘12V’ was applied - and the resistor reduced coil load with the engine running. in early cars, the resistor is usually by the coil, and the bypass included in the starter relay. Or the resistor is by the coil, and the bypass done by ign key ‘crank’ power…

Weak sparking may of course be a coil issue - changing the coil is then a remedy. But the ign protection relay has no bearing on the ignition - the ignition set-up is separate independent sub-system, powered from the ign key…

xj6 85 Sov Europe (UK/NZ)

Hi Frank
No I haven’t cleaned the points though I did check the gap at 14 thou. I will take them out and clean and reset them but grey wet and windy today so will have to wait till Thursday when weather promises to be better. I will look for a ballast resistor but I think that the coil, gold in colour, is a 12 volt unit that was changed by a PO and at first sight nothing close to coil that looks like a resistor. Setting points not real easy because car is automatic so I can’t rock it to get the peak of the dizzie cam. Do you know of a way to do that. The car has the original huge York aircon compressor which makes getting a spanner anywhere near the crank bolt close on impossible. Maybe if I spin the engine with all plugs out it will stop on a cam lobe.


Hi again Frank
I just checked the circuit diagram in the E155 manual, circuit diagram W54955069 which is for cars up to 1L-53096 and there is no ballast resistor. there is one in the later series 1s from 1L-53097 which is circuit diagram W05494925.My car is 1L50267-BW so no ballast resistor. Just for info.