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Author Topic: Ignition problem from one week to the next.  (Read 536 times)
Jon Weywadt
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« on: March 02, 2019, 05:07:32 pm »

Can anyone suggest the probable cause of the ignition problem that occurred from one week to the next.
A couple of weeks ago I drove the car which started fine and the engine ran smoothly with plenty of power.
The next week it was hard to get it started and once it ran it sputtered and back fired and had little power. I was able to drive it but had to keep high rpm`s to get anywhere. Power was poor and constant bangs from the exhaust.
The spark plug cables seem fine and are securely connected. There also does not seem to be any shorts.
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Matranaut par excellence Cool
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« Reply #1 on: March 02, 2019, 07:46:46 pm »

Can anyone suggest the probable cause of the ignition problem that occurred from one week to the next.
A couple of weeks ago I drove the car which started fine and the engine ran smoothly with plenty of power.
The next week it was hard to get it started and once it ran it sputtered and back fired and had little power. I was able to drive it but had to keep high rpm`s to get anywhere. Power was poor and constant bangs from the exhaust.
The spark plug cables seem fine and are securely connected. There also does not seem to be any shorts.


Check the ignition timing first, the distributor clamp bolt may have come loose and the ignition timing moved?
This could explain the poor power and banging.

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Colin
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« Reply #2 on: March 04, 2019, 07:51:35 pm »

There was a known fault with the distributors, under the plastic cover, under the rotor arm is a cross shaped thing, these have been known to  slip on the shaft... Speak to Roy, knows more about this fault than I do...
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Jon Weywadt
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« Reply #3 on: March 25, 2019, 01:15:42 pm »

There was a known fault with the distributors, under the plastic cover, under the rotor arm is a cross shaped thing, these have been known to  slip on the shaft... Speak to Roy, knows more about this fault than I do...

I have cleaned and dried the distributor and cap. I can get the engine to run on 3 cylinders but get an occasional back fire.
I suspect that the number 2 plug is fouled because the valve seal is worn.
I have new seals, but no way of replacing them.
I Will try to get instructions from Roy, since there was a post about replacing them and  a tool to do the job.
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Matranaut par excellence Cool
roy4matra
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« Reply #4 on: March 25, 2019, 11:02:12 pm »

There was a known fault with the distributors, under the plastic cover, under the rotor arm is a cross shaped thing, these have been known to  slip on the shaft... Speak to Roy, knows more about this fault than I do...

I have cleaned and dried the distributor and cap. I can get the engine to run on 3 cylinders but get an occasional back fire.
I suspect that the number 2 plug is fouled because the valve seal is worn.
I have new seals, but no way of replacing them.
I Will try to get instructions from Roy, since there was a post about replacing them and  a tool to do the job.

Hello Jon,

If it is misfiring on one cylinder, and the distributor and H.T.Leads seem fine, then when you remove the plugs they should indicate where the fault lies.  Normally all the plugs would look the same, but when one cylinder is misfiring, the plug from that cylinder will be different and its condition should indicate the type of problem.  Black and wet would indicate excess fuel or oil.  Excess fuel will smell of fuel whilst oil will be thicker and feel oily.  If it is dry and clean it could be no fuel is getting there at all.

I can't remember, are you using twin side-draught carbs. (what type), or the single down-draught Solex carb?

If you were using a single down-draught carb. it would be almost impossible to have no fuel to only one cylinder, but obviously with twin side-draught carbs. giving one venturi per cylinder it is possible.

You say one week it was running fine, the next it was poor.  Has it remained poor since, or has it gone back to being good (I ask as if it is the latter, that would indicate an intermittent fault).

Since your other post on the valve seals shows you had some of those valve seals with the white centre sleeve, are they fitted at present?  If you have them on the engine, I might suspect a seal has failed.

Roy
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jlg
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« Reply #5 on: March 29, 2019, 11:00:29 pm »


Jon,

Have you checked your vacuum hoses (light lifting and brake servo)?

Once my Murena lost some power and was banging extremely loudly out the exhaust. I took the spark plugs out and 3 were sooty (my car runs rich when it has been stuck in slow traffic like it had been that day) while one was super clean. It turns out that the vacuum hose for the headlight lifting system had become disconnected so one of the cylinders was running extremely lean which caused the explosion to occur in the exhaust system. I changed the hose, replugged it and it fixed the problems.

JL.

 
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