driving my 54 XK 120 OTS on my last outing, I had driven about 30 miles and was almost home when suddenly the engine dies. The engine was running fine, with no problems. I pull off the road and tried to restart the engine. I could hear the SU fuel pump clicking slowly trying to maintain fuel pressure, but the engine would not fire up. I had the car hauled home. I have a pertronix ignition system, no points, with a flame thrower coil. Car ran very well prior to the failure. I checked spark to each of the plugs and I could see a spark so I assume the ignition system is ok. I need help getting my XK running again.
Give the distributor a twist and see if it’s loose. If it’s tight then
spray some ether into the carbs and see if it starts.
Mike Eck
New Jersey, USA
www.jaguarclock.com
'51 XK120 OTS, '62 3.8 MK2 MOD, '72 SIII E-Type 2+2
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http://forums.jag-lovers.com/users/neil_skipper1 Neil_Skipper1
http://forums.jag-lovers.com/users/neil_skipper1 Neil Skipper
March 25
driving my 54 XK 120 OTS on my last outing, I had driven about 30 miles and
was almost home when suddenly the engine dies. The engine was running fine,
with no problems. I pull off the road and tried to restart the engine. I
could hear the SU fuel pump clicking slowly trying to maintain fuel
pressure, but the engine would not fire up. I had the car hauled home. I
have a pertronix ignition system, no points, with a flame thrower coil. Car
ran very well prior to the failure. I checked spark to each of the plugs and
I could see a spark so I assume the ignition system is ok. I need help
getting my XK running again.
Been there, done that; being hauled home is ignominy. 
- Just because the fuel pump clicks slowly does not mean fuel is being sucked out of the tank. Check all filters, in the carbs, pump, any added inline devices, even the one in the tank drain plug. That’s where my trouble was, a pile of rust blocking the suction tube, it never got as far as the clear plastic inline filter.
- Just because you see spark at the plug wires doesn’t mean the spark will jump across the gap inside at 120 psi compression. At my last coil failure episode the spark tester light showed flashes, but there was no cylinder firing until I changed the coil.
Petronix with a flamethrower is as reliable as you can get, provided the coil is the correct one. (check the spec for the petrol you are using). Mikes suggestion to spray some starting fluid in whilst cranking is a god idea as if your car tries to start you know immediately its a fuel issue. Oe other thing to check is the spark plug colour. are the plugs very sooty?
Finally assuming you have a regular SU fuel pump then it should not continue to ‘tick’ with just the ignition switched on. it should tick until the fuel bowls are full then stop. if it continues to tick then you have to find the source of that leak. If the leak is via the float chamber valves this will cause an over rich mixture which causes a problem when trying to start the car. If you have a modern fuel pump you can ignore this
Best regards
Rob, Thanks for the suggestions. I cleaned the plugs and checked the gap this morning, they did have carbon buildup. I also checked the distributor and it is tight and looks ok. I tried starting the engine with some starting fluid but no go. I think you might be right, the coil may be the culprit. I am ordering one today. If it is not the problem, it’s always good to have a spare.
Thanks again for your help.
Neil
I had this happen while on a short drive last summer. Engine was running perfectly and simply shut down. Did all the same checks mentioned above and turned out to be a bad coil.
Best of Luck.
You could have a fuel blockage and I would take the fuel pipe off that goes to the fuel bowls and see if it’s coming out – and also see what the pressure is while you are at it.
You could have a ticking noise, but the diaphragm in the pump is damaged and you will have insufficient pressure to fill the carb bowls up.
if you do have pressure - have a quick look at the fuel bowls and see if there’s any fuel in there.
Clean them out while you are at it.
The new fuel regs put more Ethanol in and eats at the old rubber in the fuel system.
If there is – it can only then be ignition timing,
Speaking very generally, electrical faults tend to propagate at the speed of light, fuelling problems move more at the output rate of an SU fuel pump.
In most cases, if the engine just stops running without weakening or as much as a cough, the problem is electrical.
I agree. The most common problem I’ve found over the years is bad grounds. Jaguar uses frame connections to complete circuits. Years ago I spent a lot of time on an inop fuel pump. Turns out the only thing wrong was a rusted ground connection to the frame. Total electrical failure could very well be battery ground connection.
Pat H.
A very basic set of triage questions:
What voltage do you measure at the battery terminals, with the ignition off?
Turn your ignition on, does the pump eventually stop pulsing?
Crank the engine choke off, does it turn over normally?
If possible measure the voltage between coil “SW” and earth, what is it?
Remove one plug per carb, are they wet?
Lay plug on earth and turn engine over again, can you see a blue spark?
Remove air filters, is there liquid fuel inside the carb throats, are they bone dry, or just a whiff of fuel?
After you have checked your coil, try replacing your rotor in the dizzy. You won’t see any crack, but if there is one, it will shut you down like an on/off switch. Also, try disconnecting a fuel line at the carb float bowl. With the ign switch briefly on, you should get a nice shot of fuel. Forget about worrying about flow rate, that doesn’t really apply when you are trying to start the engine.
Well I’m back with my engine failure, ref the initial post with the engine stopping. I believe that I have an electric issue vs a fuel issue since the engine does not cough/sputter then die. I found that if I turn off the key, then turn it back on, the engine will start and run for a short time, 5 to 10 minutes then stop again. looking at the wiring diagram for a 54 XK120, I see that the voltage regulator battery charge contact is parallel to the distributor. could that be a problem. Thank you for your input.
Neil
Your problem could simply be an intermittent ignition key switch.
Mike Eck
New Jersey, USA
'51 XK120 OTS, '62 3.8 MK2 MOD, '72 SIII E-Type 2+2
Mike, great suggestion. I will look at that.
Mike, if the ignition switch was bad, would the ignition light be on? Thanks for your help
Neil
If an intermittent ignition switch caused the engine to stop it would act the same as if you had turned off the ignition, so the IGN light would be off. Turning the key off and then back on could re-establish contact and the IGN light would come on.
I had this problem with my E-Type, where the engine would suddenly lose power in traffic. If I turned the key off and on again the engine would restart and I could go on my merry way. This worked fine until the switch gave up the ghost completely when I was 400 miles from home. I used clip leads to jump the switch and drove home that way.
Mike Eck
New Jersey, USA
'51 XK120 OTS, '62 3.8 MK2 MOD, '72 SIII E-Type 2+2
Condenser or coil would be my first guess.
I was thinking coil as well as maybe the pertronix I had replaced my points and condenser with. Interesting note, Mike thought it might be the key switch and I have not eliminated that. So I am driving, engine running like a champ, accelerating really good then boom, nothing. I put in clutch, turn off key then back on, let out clutch and the engine is running again. When I turn off the key I do notice that something other than the engine stops running, maybe the fuel pump, nothing else electrical is on right? A real puzzle?
Thanks for helping me with this.
Neil
probably the easiest for you is to try by substitution. In the first instance you could try a temporary link to bypass the ignition switch. (use the wiring diagram and find a convenient place to run a live feed to the coil.)
then move on to coil etc. Also don’t forget your earth connections. start with the main battery to chassis connection then the chassis to engine block.
Try hotwiring the ignition to a second battery, bypassing the ignition switch. If the car still behaves the same way then it’s your Pertronix, or the coil, or the condensor (if that is retained with the Pertronix).