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Wales
by Joske Vermeule, September 1
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Jun 14th, 2026
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Joined: Dec 2017
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Talk Morgan Expert
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Talk Morgan Expert
Joined: Dec 2017
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On taking the M3W out for a run today I suffered intermittent hesitant performance and some backfiring, at idle it kept "farting" and then stalled. On checking the spark plugs one was fouled with black soot and the other normal. Changed the plugs and engine running as normal it would seem the one cylinder is running rich, can anyone point me as to why this might be?
Bruce
1964 4/4 Series V Comp (Megan)
1994 +8 (Maurice) tis no more
2013 M3W (Olga)
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Joined: Feb 2019
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Talk Morgan Addict
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Talk Morgan Addict
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Fuel delivery system with one getting more fuel than the other?
2019 M3W Sold and is now in Las Vegas enjoying the showgirls :-)
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Joined: Feb 2016
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Talk Morgan Regular
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Talk Morgan Regular
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It could be the fuel to air mixture in the involved cylinder is higher or there could have been insufficient combustion over a period of time due to an electrical issue on that side. Think of the simple things first. Perhaps the spark plug went bad or if you use spark plugs with a removable terminal nut that big x wedge has a tendency to loosen them up quite a bit perhaps resulting in poor electrical conduction ( the affected side terminal nut loosening more significantly than the other side ). I use the Harley-Davidson equivalent spark plug for this reason because it’s terminal nut is fixed. Simple suggestions to think about before trouble shooting with a mechanic. Plugging into the ECU might provide some insight.
Last edited by Sportster; 06/05/20 02:17 AM.
2015 M3W, Morgan Aero Racing Stage 1, Garage 56 Stage 2, sport black, saddle tan, jeweled SS dash.
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Joined: Dec 2017
Posts: 2,223 Likes: 183
Talk Morgan Expert
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Talk Morgan Expert
Joined: Dec 2017
Posts: 2,223 Likes: 183 |
It could be the fuel to air mixture in the involved cylinder is higher or there could have been insufficient combustion over a period of time due to an electrical issue on that side. Think of the simple things first. Perhaps the spark plug went bad or if you use spark plugs with a removable terminal nut that big x wedge has a tendency to loosen them up quite a bit perhaps resulting in poor electrical conduction ( the affected side terminal nut loosening more significantly than the other side ). I use the Harley-Davidson equivalent spark plug for this reason because it’s terminal nut is fixed. Simple suggestions to think about before trouble shooting with a mechanic. Plugging into the ECU might provide some insight. I think it could be an electrical issue, when I removed the fouled plug the top was loose. The new plug is tight so will see how that performs.
Bruce
1964 4/4 Series V Comp (Megan)
1994 +8 (Maurice) tis no more
2013 M3W (Olga)
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Joined: Feb 2016
Posts: 775 Likes: 33
Talk Morgan Regular
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Hi Bruce,
The removable terminal nuts loosen just after a few drives. I found myself frequently tightening them until I finally went to a plug design with a fixed terminal nut. So check them periodically. Also make sure the plugs are gapped appropriately.
By the way we share the same first name.
Last edited by Sportster; 06/05/20 02:36 AM.
2015 M3W, Morgan Aero Racing Stage 1, Garage 56 Stage 2, sport black, saddle tan, jeweled SS dash.
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Joined: Feb 2019
Posts: 3,857 Likes: 2
Talk Morgan Addict
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Talk Morgan Addict
Joined: Feb 2019
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Hi Bruce,
The removable terminal nuts loosen just after a few drives. I found myself frequently tightening them until I finally went to a plug design with a fixed terminal nut. So check them periodically. Also make sure the plugs are gapped appropriately Good suggestion.
2019 M3W Sold and is now in Las Vegas enjoying the showgirls :-)
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Joined: Dec 2017
Posts: 2,223 Likes: 183
Talk Morgan Expert
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Talk Morgan Expert
Joined: Dec 2017
Posts: 2,223 Likes: 183 |
Hi Bruce,
The removable terminal nuts loosen just after a few drives. I found myself frequently tightening them until I finally went to a plug design with a fixed terminal nut. So check them periodically. Also make sure the plugs are gapped appropriately.
By the way we share the same first name. Bruce; Many thanks. Could I ask the number of the plug you use?
Last edited by britmog; 06/05/20 03:02 AM.
Bruce
1964 4/4 Series V Comp (Megan)
1994 +8 (Maurice) tis no more
2013 M3W (Olga)
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Joined: Feb 2016
Posts: 775 Likes: 33
Talk Morgan Regular
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Talk Morgan Regular
Joined: Feb 2016
Posts: 775 Likes: 33 |
Thanks Lightspeed.
Your welcome, Bruce.
Harley-Davidson HD6R12. Gap with wire gauge to .040.
Last edited by Sportster; 06/05/20 03:21 AM.
2015 M3W, Morgan Aero Racing Stage 1, Garage 56 Stage 2, sport black, saddle tan, jeweled SS dash.
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Joined: Dec 2017
Posts: 2,223 Likes: 183
Talk Morgan Expert
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Talk Morgan Expert
Joined: Dec 2017
Posts: 2,223 Likes: 183 |
Discovered there was also a loose connection at the coil end of the lead too, added to my pre-flight checks to make sure leads are tight.
Bruce
1964 4/4 Series V Comp (Megan)
1994 +8 (Maurice) tis no more
2013 M3W (Olga)
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Joined: Aug 2011
Posts: 398 Likes: 1
Learner Plates Off!
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Learner Plates Off!
Joined: Aug 2011
Posts: 398 Likes: 1 |
I have had these pop off twice.
They are both zip tied on now!
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