Joined: Aug 2017 Posts: 450 Threads: 13
Reputation:
9
Location: Dunchurch, Warwickshire
Hilda, our ridiculously unreliable RP saloon, has come up with yet another way to plague her long-suffering owners. After doing 600 miles this year with only a broken contact breaker points heel, dodgy rotor arm & distributor cap, intermittent main fuse, suspected blocked oil jet, stuck advance & retard mechanism, indicators flashing at double-speed, leaking head core plug, rubbing rear brake and a rear spring pin halfway out, her latest trick is: after about a couple of miles the engine cuts out for 3 seconds, then continues for about 6 seconds, then cuts out for 3 seconds, then resumes for 6 seconds, and so on.
It's not (or unlikely to be) fuel, as the SU float chamber has petrol and fuel problems tend not to be on/off like this is. I have changed the condensor which made no difference. Before I try changing the coil, has anyone come across anything like this before?
David
Joined: Jun 2022 Posts: 129 Threads: 21
Reputation:
1
Location: Exeter
check the:
Fuel filter,
points,
coil,
distributor lash,
king lead insulation
Joined: Mar 2015 Posts: 5,225 Threads: 223
Reputation:
59
Location: Scotchland
Sounds like an ignition wire fault - in the switch.
This is the kind of thing that will instantly kill electronic ignitions, which I think you had some trouble with too.
Run a live wire from the battery to the coil and see if it remains. Worth a try.
Joined: Aug 2017 Posts: 166 Threads: 30
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David, I had a similar fault on a RM, a while ago. It turned out to be a poor electrical connection on the coil SW terminal. Just a thought.
Joined: Jan 2018 Posts: 64 Threads: 7
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Hi David, FWIW I would change the coil. Simplest way of excluding it as a cause?
Joined: Aug 2017 Posts: 818 Threads: 72
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I had something like this with one of those red-key battery isolators.
Joined: Aug 2017 Posts: 545 Threads: 19
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Location: Hampshire UK
19-08-2022, 09:00 AM
(This post was last modified: 19-08-2022, 09:00 AM by John Cornforth.)
Hi David
I have a suggestion for testing the ignition switch / coil feed whilst driving. Wire up a small 6 volt bulb between the Switch terminal of the coil and Ground, and place it somewhere easily visible whilst driving. This way you may be able to "catch it in the act", i.e. see if the bulb goes out at the same time as the engine dies.
The ignition switch part of the PLC switch does eventually wear and can become a little intermittent after 80 or more years. You may even find that the bulb flickers a bit as you turn the key, which is a sign of wear.
On the subject of red-key battery isolators, of the three I have tested (at high current) all have shown inconsistent contact resistance and I wouldn't trust any for use on a 6 volt car.
Joined: Dec 2017 Posts: 1,145 Threads: 67
Reputation:
8
Location: Nottinghamshire. Robin Hood County
Car type: Austin Ruby Mk1 1935
19-08-2022, 09:40 AM
(This post was last modified: 19-08-2022, 09:42 AM by John Mason.)
Hello David, The thing that puzzles me is the three then six second recurring stop start of the engine. Could it be a faulty coil that once warm fails then takes three seconds to cool enough to re start but after six seconds is to hot again and fails. Then the cycle just keeps repeating. Just another point. It could be the condenser that is doing this for the same reasons.
John Mason.
Would you believe it "Her who must be obeyed" refers to my Ruby as the toy.
Joined: Aug 2017 Posts: 395 Threads: 33
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Location: Garden of England
Car type: ARQ Ruby July 1936
Talking condensers, between my brother and myself we have had 5 new condensers that have failed within the last four months. These have been purchased through our normal suppliers with the exception of the last which failed within less than 10 miles on the clock and this was procured from a distributor specialist.
Having just rebuilt my distributor and taking Ruby out for a run to the local A7OC meet it failed within five miles from leaving home. Replaced with yet another new one.
