Being driven mad

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james couper
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Being driven mad

Post by james couper » Mon Feb 18, 2019 9:47 pm

Engine starts Ok, everything normal rev.s up Ok, but after 2 / 3 minutes engine cuts out wont restart, leave for an hour starts ok, then stops again after 2/ 3 minutes.
Changed coil, points, cap, rotor arm no difference, after car stops still getting spark, could be fuel but why restart after an hour.
The only thong slightly hot is the ballast resistor.
Have played around with carburettor, apart from running a bit rich everything seems ok.
If i keep the car at high revs i.e. 1500 2000 it seems to run longer, but when car is up to temperature engine stops when you take your foot off the throttle.
Any suggestions.



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Post by AJL Electronics » Mon Feb 18, 2019 10:39 pm

Massive air leak. Do the brake cleaner test around all intake joints.


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Post by james couper » Mon Feb 18, 2019 10:50 pm

Why should it suddenly happen, have tried it using WD40 made no difference, but will try again with brake cleaner.



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Post by Corky » Tue Feb 19, 2019 6:56 am

Could be a fueling problem.

Check that the breather in the fuel cap isn’t blocked. Or collapsing/blocked hoses. Particles in the carb.


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Post by philhoward » Tue Feb 19, 2019 8:17 am

2 to 3 minutes sounds like enough time for components to start to warm up - possibly a crack or split opening up? It probably ties in with when the choke flaps start to open so it loses the very rich mixture it needs to start, overcome by the huge air leak AJL suggested?

Ballast resistor will get warm - that's why it's ceramic and kept away from stuff that melts easily.

I'm assuming it's a cough, revs dropping until it finally dies (suggesting fuel) rather than a sudden death (suggesting electrical) - the fact you have confirmed spark does say it's fuel (air) related but have you confirmed there's fuel there (filter lid off, operate throttle and you should see the accelerator jets squirting)? No fuel is a different issue to too much air but both will stop it running :)


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Post by TrevorG » Tue Feb 19, 2019 8:30 am

I'm glad phil has mentioned the way the car cuts out as this is important. I do feel you need another person with you when experiencing the problem. Unless it is obvious it is a fuel problem, I would try to confirm whether it is fuel or spark related and the easiest way is to use a visual aid on a plug lead (like a timing light) and see if the spark goes. one reason for doing this is that depending on which coil you have, they can break down when warm (especially an oil filled one that has a crack). Then you can attack the fuel system before affecting any settings that can further exacerbate the problem.
Good luck and hope you crack the problem.



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Post by james couper » Tue Feb 19, 2019 4:26 pm

No it cuts out without a cough, sudden depth, replaced some wiring thinking to coil, distributor thinking this maybe causing a leak voltage, no difference, i think i will have to look at a fuel issue i have stayed away from this being the problem as it restarts at a later stage. Just installed a new 1.5ohm coil thinking the old coil was the cause. It still has the original 40 year old alternator i feel is on its way out but that should not case it to cut out just not recharge the battery. I think i will have to re-set the carburetor settings as i have played around so much trying to solve this issue, i think i will have to back to normal settings and see what happens.



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Post by rkclodhopper » Tue Feb 19, 2019 4:45 pm

If your car still has the standard fit 38DGAS Weber carb you cannot do much to it, settings wise, that will prevent the engine running, the two adjustment screws only alter the idle mixture which only leaves the throttle stop screw, all the running settings are none adjustable fixed jets inside the unit.
With the air filter removed and someone else on the accelerator pedal and ignition key, start the engine an hold it at 1500/200o rpm, when it starts to die have a small amount of fuel to hand and pour it down the choke, if its dying through lack of fuel the poured in fuel will keep it running for a short while, half a egg cup would work. A small syringe for adding the fuel would be ideal but be careful while doing this.
If it runs for longer it could eliminate a fuel supply issue.


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Post by rebel alliance » Tue Feb 19, 2019 5:08 pm

Has it got an auto choke?..if so maybe its the idle mixture screws in too far so when the choke comes off you have a weak mixture



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Post by AJL Electronics » Tue Feb 19, 2019 5:15 pm

If you are not sure about the carburettor, set it to three and a half turns out each side as a starting point.


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Post by philhoward » Tue Feb 19, 2019 5:41 pm

james couper wrote:
Tue Feb 19, 2019 4:26 pm
No it cuts out without a cough, sudden depth, replaced some wiring thinking to coil, distributor thinking this maybe causing a leak voltage, no difference, i think i will have to look at a fuel issue i have stayed away from this being the problem as it restarts at a later stage. Just installed a new 1.5ohm coil thinking the old coil was the cause. It still has the original 40 year old alternator i feel is on its way out but that should not case it to cut out just not recharge the battery. I think i will have to re-set the carburetor settings as i have played around so much trying to solve this issue, i think i will have to back to normal settings and see what happens.
Sudden death suggests electrical and if you've already done the coil (and it's not the points/condensor) then the next suspect would be the ignition switch. If currently it won't restart immediately, try a jumper wire from battery positive to the top of the ballast resistor. Thinking out loud though, the starter bypass circuit should kick in (which would give the symptom that it tries to fire until you release the key, then dies - assuming that wire is present and correct).


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Post by james couper » Wed Feb 20, 2019 9:27 pm

I think i have got the problem down to two areas to look at one the carburettor the other ignition switch, but feel its the carburettor. Car started first time as usual run for about 2 / 3 minutes, sprayed WD40 around carb no difference, then cut out, getting spark, removed carb. fuel filter, turned engine plenty fuel. Poured fuel down carb. still did not start. Screwed out carburettor mixture screws, gave it a bit heavy throttle, car started run for 8 minutes stopped but started straight away. Only problem now is that the spark plugs black too rich. Could be dirt in carb. Does anyone know were i can get new mixture screws ( car SE6A therefore mixture screws without ( screw heads) tamper proof carb, most carb. rebuild sets contain mixture screws with screw heads, these are too short.



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Post by AJL Electronics » Wed Feb 20, 2019 10:20 pm

No reason to replace the mixture screws unless they have been butchered. Just make sure that they are gently bottomed before unwinding three and a half turns and leave them alone. Wind up the idle screw though. Start the engine and have a tablespoon of fuel to hand in a syringe or some other suitable container. When the engine starts to falter, put the lot straight down the choke barrel and note the response. It would be interesting to know where the choke flaps are during the warm up from cold and at cold.

One other thing to check is the vacuum takeoff between the throttle quadrants. It should be blanked off.


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Post by philhoward » Thu Feb 21, 2019 6:04 am

When you say it stopped after 2 mins but you had spark, where did you have spark? At the coil or at least one spark plug?


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Post by james couper » Thu Feb 21, 2019 9:10 pm

I don't know if this is a new problem or the original issue, car started first time as normal stopped after 1 minute, removed spark plug no spark, tested for voltage at coil + side no voltage, no voltage at resistor. When testing noticed a small puff of smoke coming out of the key area. Removed the wiring to back of the ignition switch everything OK. However the ignition switch feels a bit rough.
Does anyone have a new ignition switch for sale.



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