Won’t start!

[SimonBrown]

My normally reliable S2 OTS won’t start.
There is fuel and it cranks over fine. However, after cranking, when I switch the ignition “off”, the engine sometimes “kicks”, as though it tries to fire without cranking. When this occurs there is a flash between the positive side of the coil and the centre HT connection.
It has a Pertonix electronic ignition with an otherwise standard distributor.
Any ideas anyone?
Thank you

[mgcjag]

Hi Simon......Im thinking probably a shorted out pertronix unit......when ignition is on you have power to the coil, turn engine over and the make/break of the pertronix/or points will fire the coil to produce HT......if the unit is shorted the coil wont fire but as you switch ignition off you break the coil cct so HT could fire.....im assuming this is the flash you see.....possibly dodgy connections on coil as well.....you will need to multimeter test....hope this helps..Steve

[ALAN COCHRANE]

Simon

You shouldn't be seeing a flash on a healthy coil under any circumstances. It sounds like you have a short in the coil which may be be due to a hairline crack in the bakelite between the LT positive and HT terminals or could be an internal winding fault. In any event change the coil for a known healthy one.
Petronix like all electronic ignition systems either works or it doesn't, there's no halfway house in my experience.

Cheers

[SimonBrown]

Thank you.
Tried a coil off my Morgan and the E Started instantly, so I put the old coil back on and it wouldn’t start. Great I thought, so I bought a new coil, fitted it and the E wouldn’t start again!
Refitted the Morgan coil again and it started instantly, then tried the new coil I have bought and this time it started fine.
However, I have noticed that when I switched the ignition off to stop the engine, it didn’t cut instantly, probably half a second delay. So I am wondering if it could be a faulty ignition switch?
Simon

[mtnjag]

Just a note, make sure the new coil is the correct ohm spec.
Check with Pertronix on correct coil for your type of unit.
If you have the cheap Pertronix you will burn it out of you leave the key on.

[PeterCrespin]

The other S2 issue - probably not relevant unless you mixed up the connections -is that there is a direct coil feed whilst cranking and indirect through the ballast resistor when not. Mixing connections can mean the coil only fires a couple of the cylinders as the engine rotates momentarily after you turn off the starter.

[josh_mayhem]

Hi all, any help would be greatly appreciated...
Have a S1 4.2 with SU carbs. Mechanical distributor.

Turns over fine, new starter motor and battery last year, after a two year restoration by CMC.
Plenty of fuel in the filter bowl.
Can hear fuel pump prime upon switching on the ignition.
Distributor appears to be rotating.
Spark plugs sparking. (Although a little sooty after a very brief two mile run after which it won't start again, having cleaned when initial starting problem occurred).
Fuel was fresh in July.
Choke mech appears to work as does throttle mech.

Ran fine for a few drives, and after a six week gap developed this issue, aside from managing to start it, got two miles in, running fine, then it died and would not re-start.

Am I missing any glaringly obvious things to check? Thanks in advance.

[christopher storey]

Note that XK engines if not started at least once a week are always difficult to start if left for a prolonged period, partly because of the very long inlet tract, and often require many sessions of cranking for 15 seconds at a time to get them going

An easy check of the overall ignition system is to rig up a spare HT lead , place one end in the centre ( HT) terminal of the coil, and the other end about 1/4 inch / 5mm from the inlet manifold , using something non-conductive to position it. Spin the engine over, and if you get good fat sparks both LT and HT are probably in good order. Then , having replaced the HT lead from coil to distributor, try an individual spark plug ( I use an old but clean plug attached to one cylinder's lead ) - if it sparks this eliminates a rotor arm fault ( unless its only becoming conductive when hot which is a well known fault) . I should then clean the plugs thoroughly and then put them in an oven at about 100C for 1 hour, and then replace them and try again . You could also put the cap and leads in a rather cooler oven - say 50C - to bake any moisture out of them

If all this fails to produce even a kick , then I would wait for dark, and spin the engine over in the dark and see if you can detect tracking ( blue streaks) on either the distributor cap, coil, or any of the leads

Good luck with it

[mgcjag]

Hi ......are the plugs getting wet with fuel when your trying to start......if not then check you have fuel in the glass bowl filter....when you try to start dont press or pump the accelerator pedal......please try to put your name and car model in the signature area it will help with future questions....and welcom to the forum im sure you will find it very usefull.....Steve

[josh_mayhem]

Thank you both.
Had checked and plugs definitely sparking when the engine turns over, turned lights off and placed a spare plug on the head whilst cranking it over.
Also fuel in the filter bowl, undid the clamp and fuel pee'd out of the top..thankfully and usually I had the foresight to put a rag underneath...

[1954Etype]

If we can't get a car to start and we have spark and fuel, we take the air cleaner plenum off and squirt some easy start into the intakes. If it fires and runs briefly, you know it has to be fuel related.

[malcolm]

There's fuel in the filter bowl - presumably the glass one low down? But is it getting up to the carburettor bowls? I know it should, but I'd take the lids off the carb bowls to ensure there is a suitable height of fuel in there. Could be needle valves sticking and not allowing fuel up. Steve asked if the plugs get wet, but can't see an answer to that.

[josh_mayhem]

Spark plugs not obviously wet, even after being cranked over a lot, although shining a torch into cylinder the piston head was visibly wet - although I guess that could be condensation?!

Will check the carb bowls for fuel. Thank you.

The only horrible thought I did have whilst out cycling yesterday was - have I put diesel in it when I fuelled last?! I don't think I would, because I always use 97/98 petrol and look at how much it is compared to regular, and not sure the diesel nozzle would fit into the tank. Probably just my mind over-thinking!