Morris Minor Owners Club

I had a misfiring, loss of power problem recently. No warning at all, car ran perfectly on outward trip then after being parked for a couple of hours, conked out after 100 yards with total loss of power. Afterwards, having been recovered to home, I got it running for about 15 minutes but it was uneven and backfiring slightly, eventually dying again

I suspected electrics as fuel supply fine. We couldn't find anything wrong with it APART from

(1) Pitted points, but not what I would call bad pitting - replaced and gap set
(2) The ends to some of the plugs - metal screw on bits - being a little bit loose - tightened

Since then its been fine. My question is whether anyone thinks these 2 problems would have caused the situation, or whether I should still be looking for something. Could it possibly be caused by a partially burnt out ignition wire ? see pic [frame][/frame]

Marion
Pleased the duff fuse issue has been resolved.
The pitting of the points /gap and the loose metal terminals on the HT leads could be just down to wear and tear.
The white wire... if it's the one feeding the coil LT side... might not be providing full battery voltage to the coil, which won't be helping things.
Testing for continuity ,Terminal by the wire to low tension lead on the side of the coil.Ignition off, remove lead from coil temporarily.Multimeter set to ohms.

Alternative , guess that it is Coil feed wire and use Volts on the Multimeter, black to a good ground, ignition on ( for just a short period )
and touch the red probe to the low tension white wire on the side of the coil.Note the voltage figure.Switch ignition off.Put the probes, still on voltage setting to the battery terminals, red probe the " + " terminal and the black probe to the " - " terminal.Are the two readings the same ? or is the coil reading lower ?

The car is running again but clearly the burnt wiring needs to be replaced as soon as possible.Battery disconnected ,splicing in a new bit of wire, soldering it to the old bit of wire, shrink wrap tubing over the join and re-attach the wire to the terminal.Re-connect the battery and test.
Bob

Prime suspect would be the condenser....

I should have mentioned that I replaced the condenser as a precaution.

Bob, re replacing burnt out wire, do you think the wire hidden in the loom is also damaged? I was thinking of fitting new wire and simply bypassing the whole run of damaged wire, both the visible and invisible parts, maybe taping it to outside of loom.

I'll need to establish where it leads to - I am guessing the fuel pump

Marion

Marion you're on the right track fuel pump or coil are the likely suspects.

Unless serious / long lasting... short loom fires usually occur near a switch or near the power consumer.A tightly bound loom acts as a bit of a heat sink.
Any loss of voltage along a piece of wire indicates damage i.e less undamaged strands to take the load."Proof positive " would be open up the loom.Not an option in the real world unless you happen to be a concours fanatic !

Once the supply end is identified, coil or fuel pump you can simply by-pass the problem with new wire end to end as suggested.Don't fix the terminal or strip new wire on one end, so you can push it through the rubber grommets in the bulk head.
Bob

I would run a temporary wire first to prove that 'fixes' it - then make it permanent in a workmanlike manner of course. Of course - it's NEVER the coil - but it can be the coil connections......

Roy
I love your comments.A man with style !!
Bob

Bob, just sourcing the replacement wire. What amps should I choose - 8.75/14 /21 /30? The fuses are all 35amp so I am thinking that the wire will go before the fuse at any of these amperage values

Marion

Marion
28/0.30 ..17.5 amp wire is typical for petrol pumps and the like , whilst 14/0.30..8.75 amps is side lights, indicators and general wiring.I'll p.m you a little later in the day re the wiring ( don't buy it yet ).Was it the coil Low Tension supply or the petrol pump or something else ?
Bob

Still 'dying' to know what that black plastic lump is - with the screw connectors....

It's the back of the early screw terminal ignition switch BMC, as fitted to pull start vehicles.

Oh right! Thanks.... I don't understand why it has 'white' wires on both sides..... Should be BLUE from A1 and then WHITE ?