Talk Morgan Forums Morgan Sports Cars Morgan Three Wheeler & Super 3 Help! Engine suddenly cut out.

Fuses arrive tomorrow hopefully and this will be my first test . Thanks.

Must need my eyesight checking Andy but having spent time searching for other end of the tenth red wire coded R80 on schematic, I found it immediately after your suggestion .

Sincere apologies Vitaloni but it routes directly to voltage regulator of alternator. I'm pretty sure if you disconnect just this cable, which appears to terminate in a 10mm eyelet, you will find a dead short at the regulator/rectifier it connects to. A replacement 50 amp fuse shouldn't blow then by way of confirmation.

If so and given unreliability of this component, a full replacement with I believe the recommended HD unit is the way to go, even if it's found to be just chaffed wiring at regulator.

I have disconnected the rectifier ( all the wires including the one going up to that red eyelet) and the fuse blows as soon as you put it in. The key is in the off position. Its not the rectifier. I have gone through all the wiring and can see nothing amiss and no areas where its been chafing.

Scratching my head but next is to disconnect starter although the main feed does not seem to go through the fuse. Will start to look at the ignition switch. I have some help who is a mechanic so hoping he has better luck. I have the 2014 wiring diagram ( lost on me) and it printed so small its difficult to read. Where can I get the earlier one, pre 2014?

Vitaloni, I understand your frustration at this phase in the fault finding. The 50 amp fuse that blows is fed directly from one of the two cables from battery positive. The other feeds starter motor directly so is isolated from your problem.

As already mentioned the permanently live feed from the 50 amp fuse splits at a splice in the loom to ten other red cables, so the fault causing a short or near short if not on single feed to splice must be on one of those ten cables or a device that one of them connects to. As the fuse feeds nothing else, I'm afraid you need to check closely again, identifying each cable from splice!

Just to repeat further relevant points regarding each of the ten suspect cables:

1) R25, R26, R27, R28, R124, R131 - each of these feeds directly an individual low current fuse in the main fuse box. So any fault after these secondary low current fuses would blow them before the 50 amp.

2) R23 and R24 are main power feeds to engine and start relays. Relays are not energised with ignition off, so unlikely to be an issue after either relay. A fault within relay also unlikely as there are no permanent ground feeds to either, but you could unplug each to verify.

3) R29 feeds ignition switch directly. Unllkely to be ignition switch unless it has developed a short to chassis whilst switched off but may be worth disconnecting.

4) R80 feeds alternator regulator directly. This you have already disproved as a fault candidate by disconnection.

5) Most important then the ten cables themselves are checked, over their full length up to the device they connect to, for chaffing/short to chassis. A multimeter set to continuity or resistance will prove existance of a short, to save blowing further 50 amp fuses by way of testing. With fuse removed place probes between none battery side of fuseholder and chassis.

Finally link to download M3W parts book which includes all wiring schematics here.

ETA: if a previous owner has "added" wiring to any of the ten cables the jury is out. Should be obvious though.

Had the same cut out issue, coming off the motorway, turns out the disconnect plug to the ignition loom is dodgy, ( this link connects to the original thread http://www.talkmorgan.com/ubbthreads.php/topics/749435/re-non-start-plus-8#Post749435 )
Have you tried wiggling the connector, could be the plug has failed and is shorting, giving rise to the blown fuse?

Any success in sorting this issue Vitaloni ?

Found the fault!!! Its the red wire that comes off the main loom behind the dash and goes to a connector ( maybe the one as mentioned by treesurveyor) and then on to the ignition.

It has been rubbing against the support for the dash ( the right upright, the edge of it) and then obviously shorted when the plastic was breeched and sort of melted itself to the metal.

Pulled it away and wrapped it with insulation tape and repositioned the wiring ( its like a birds next behind the dash) with a cable tie and all seems OK although there is lots to put back before I start the car.

But the ignition is now coming on and lighting up the dash so I am pleased.

Thanks for all your help and especially to Richardv6 for his efforts on my behalf.

Glad you found it

It had to be one of the red cables I mentioned. If it's happened to one car it will probably happen to another!

Do have a close look at the rub point before you put everything back together, particularly if the cross sectional area of the cable has been diminished. Each time it shorted out, some of the copper would have been vapourised so it is possible that some of the strands could be broken and then might over heat in the future.

Very pleased to hear you found the source, but heed deejays warning, might be better to splice some new cable in. There are lots of good waterproof/heatshrink/solder connectors out there. Best to prevent recurrence, or possible electrical fires of you can, whilst its still accessible.
Best wishes
Phil