Hello, have faced the folowing problem with my jag mk2 (3.8/1961). The car has not been in much use the latest years. The problem is;
when taking a fairly short drive lasting for thirty to forty minutes the engine suddenly starts to “coff” followed by a stand still. Try to start it again with no success, the starter and engine turns but it do not fire. The car gets towed home and after a rest it starts and run normally. This was the only trip this year. Excactly the same happened last year. From Cold, the car starts easily and runs smoothly and absolutely no problem before driven for half an hour or so.
Three years ago I changed distributor and coil to peretronix flame thrower i.e electronic ignotion.
Is there any experience by the jag lovers of unstability with this type of system. Is it affected by heat since problem occurred in both case after “Equal” time interval and the engine has got the heat.
Is fuel a more likely problem? Dirt in petrol filter, it does look dirty through the glass. Dirt from petrol tank?
Will this come and og in the way I descrtibed? Has anyone any good ideas?
I run Petronix and things get hot and I never have problems like this. This sounds like a dirty fuel tank. Do you have a filter BEFORE the pump? get some of the disposable ones. and you will probably see them plug up quickly. If your glass bowl is cloudy to may already be getting particulate into your floats and needles. This is easily rectified with a simple disassembly. Do NOT blow high pressure air towards the carbs and this will not be good.
Buy a new glass bowl gasket or three before you take things apart as it is surely perished and will leak like a sieve when reassembled. ( I don’t run a bowl as I feel it is a source of potential danger and vapor locking) This bowl should not get dirty if the filters are working. Another thought is that the in tank fuel screen is sucking enough after short drives to accumulate enough material to plug it up and then all of that gunk fall off as the fuel in the tank sloshes around.
Distributor rotors and caps are known to have these symptoms for some of the replacements, including later Lucas parts. “Tracking” on these parts can be temperature dependent, going bad when warmed up and then good after sufficient cooling. And the internal screw in the center of the distributor cap which receives the main high voltage coil output can have a temperature-dependent intermittent connection to the high voltage if some corrosion is present at the screw/high voltage center conductor contact. This screw normally is not visible when inspecting a distributor cap, the carbon bush and spring must be removed and the screw taken out for inspection.
Your problem sounds reproducible, and possibly heat related. If it were fuel, I’d think the problem wouldn’t wait 30 min before rearing its ugly head. Tho I’ve read a lot on this forum about engine compartment heat vaporizing fuel in the carb bowls. BTW, your fuel tank is vented, right? You could try driving with a loose gas cap to see if that fixes it.
My money would go to an ignition problem. I’d pull your pertronix coil & try running your old coil as a start. Heat can trigger a fault in a defective coil. If it keeps happening, I’d take the car out, drive til it stops running, and check immediately for spark by pulling the distrib center wire and holding it close to a head bolt while someone cranks the engine with the key on. At least then you’ll know which system to investigate furthur. Good luck.
David
'62 Mk2
'53 MGTD
'61 R 69S
And assorted other old junk.
Thanks for advice. I also think that the problem might be with the coil. I do not fancy driving to repeat the problem needing assistance from service/towing car. Do you think that I can repeat the problem by running the engine for half hour outside the garage? Regards Øystein
61Mk2
68 Mustang 390gt S code
One technique I’ve learned when encountering these problems is to drive a five to ten minute distance and back to the house or to go shopping and also bring a book. Car can run fine to get to convenient parking space, then allow engine off heat soak to bring up the engine compartment temperature and induce non-start mode. Then do a check on spark at end of one lead at spark plugs, then check spark at high voltage lead off the coil. No spark at plug tells you the high voltage not reaching that plug (possible rotor, cap, coil, or intermittent wire on low or high voltage side of ignition circuit). No spark at coil tells you the high voltage is not coming out of coil (possible coil failure or intermittent low voltage side of ignition circuit). If you have spark at plug and can tell it
is strong enough to function well, then problem likely not spark related.
If it is hot ignition parts causing non-start, put the bonnet up and let the engine cool more quickly. If you try replacing individual parts, the time to replace may allow sufficient cooling to restart independent of which part you switched. To double check a replaced part, run the car through the non-start cycle and see if it repeats.
If your distributor advance is improper at idle or high rpm that can lead to excessive engine compartment temperatures. If your ignition circuit does not have a load resistor in the coil or external then coil internal temperatures may run too high from excessive current on the low voltage side.
Good luck on a stress-free method of solving among the fuel and electrical ideas from all the listers.
Maybe. You could also take the coil out of the car and get it tested by an
auto electric specialist. Explain to them that you only have a problem when
the car is warmed up. If you do leave the car running, make sure you don’t
overheat it, and don’t forget you left it there!!!
I also have a Mustang, a plain vanilla '65 with a 6 cyl and auto. Very
stock, and cute. Send me a picture of yours. David
For info, tested the car, running the engine in the garage. After approx 40 minutes it started coffing and stopped. It did not start again. Run the starter and checked coil and plugs for sparks, both ok. Then it comes down to fuel. Carburators, petrol filters and tank. Parts are ordered for further investigation.
Now, a year has gone, but problem search has been a little up and down. A final conclusion has yet to be drawn. Have also read a few more suggestions also incl. fuel tank etc.
The car has not been driven, but the engine has been running in the garage a few times following testing of possible solutions. The “program” I have tried out is ;
The fuel filter (in the glass bowl) is replaced. The old one absolutely clean
The float chambers cleaned, floaters checked, damper Chambers, pistons , needles cleaned, no dirt everything clean and ok.
New fuel pump installed.
Blown through pipe (reverse) from pump to tank
Drained the fuel tank an installed new drain plug with brass filter. Not necessary since the old one was clean and looked like new.
As stated, the engine has been run at various revs a few times unrtil it stops, still between half an hour and an hour.
Last attempt I also changed the coil. No improvement. Just after it stopped I tried to restart with no luck. Then took out one of the spark plugs to check if it was wet, and it was.
For the sake of order sparks are observed when attemting restart. Even though my view is that the problem is With the ignition system. The heat is affecting it. It could be a fabrication problem or disturbance in the electronic distributor. This is how far I have come. I will probably check the market for various electronic systems.
If anyone has ideas not touched upon, they are welcome.
Regards Øystein Jag Mk2
Some more things you might try. Run the engine at night or in a dark garage and see if you have electrical sparks outside the sparkplug wire. Run the engine until it quits running and then spay propane gas or starting fluid into the intake and see if this added source of fuel causes combustion.
Is your MK2 still positive earth and is your Pertronix distributor also positive earth?
When you do get the engine to run can you measure the intake manifold vacuum?
Read the voltage at the coil before the engine quits and after it quits.
Can you provide more information on the car`s mechanical history? Pete
The mechanical history of the car is nothing special. I bought it from California in 1995. The only mechnical modifications done to the car is change of steering to rack and pinion + alternator installation. Then also change of the ignition system to electronic.
The reason for doing that was that it was difficult to get hold of good quality rotors. They often failed in getting contact to the plug wires.
I have also once used “start gas” in order to get it started immediately after it quitted. No combustion.
The car is a left hand drive and it has negative earth. All electrical equipment is bought with that in mind.
The engine was running perfect after installation the electrical system. The problem occurred a year or so later. The car has been in the garage for the last two years apart from two 45 min drives in the surroundings and being towed home.
After all it all boils down to fuel system or ignition system. My view is that the fuel system is a simple mechanical system which has worked very well throughout the years. The electronic system is more vulnerable and can easier be subject to problems. I have seen from the Forums base that most members having installed lectronic ignition is very happy. I might have got a “Monday” system.
You have yet to check the fuel tank breather for being clear, although this was suggested in one reply. The problem is typical of a blocked fuel tank breather.
When your car quits after running for a period of time you think it is either an ignition fault of a lack of fuel. To determine which it could be.
1: Get an automotive ignition spark tester ( just a light inline with plug wire ) and test for spark.
2: Spray starting fuel into the intake and check for any combustion
These are basic and non invasive and simple and might give you more direction to a solution. Pete
I have put a purpose type lamp/bulb between thje spark plug and distributor to look for spark. I can see spark.
I have done exactly what you suggest. It does not restart or combust immediately following quitting if using start gas. It needs to rest a while before it will restart.