Engine cuts out intermitantly

[Karlos]

Engine on my 1850HL has begun to cut out at any speed, load or temperature. It's as if the ignition has been switch off but everything stays on, ignition light goes on, heater blower stays on, lights, everything really except the engine. Also though at the same time the fuel and temp gauges go to the bottom of the scale - as if they were reading the wrong way or polarity was reversed. After about 10 mins of checking connections on the distributor, coil and fusebox the engine started again and was fine. Then it did it again a couple of days later. I can't find any loose connections under the bonnet, any ideas anyone?

Thanks for any suggestions.

[GlenM]

It could be a faulty coil, they sometimes have an intermittent fault which shows up when the car has been running for a while and the coil warms up.

That wouldn't explain the gauges dropping back though.

[Edin Dundee]

Damaged alternator?

[Jon Tilson]

Loss of gauges suggests something at the common point of source, which is the ignition switch.

Unlikely - Ive only ever had the starter bit of that switch fail.

If the coil wiring has been sourced from the fuse box to replace the ballast resistor it could be the connection
at the fuse box too.

Jonners

[Karlos]

Thanks for the suggestions, will check it over again tonight. Would a faulty voltage stabilizer have anything to do with it I wonder?

Also the rev counter will not register until I give it a knock on the front of it (with the engine running of course) so maybe there is something loose but not necessarily related behind the dash.

[GlenM]

Thanks for the suggestions, will check it over again tonight. Would a faulty voltage stabilizer have anything to do with it I wonder?

Also the rev counter will not register until I give it a knock on the front of it (with the engine running of course) so maybe there is something loose but not necessarily related behind the dash.

A faulty voltage stabiliser would explain the fuel and temperature gauges dropping but not the cutting out. Maybe you have two separate faults.

It is quite common for the Smiths rev counters to stick until the car has been revved, or you give them a tap. The 1500 Midget I have does the same.

[MIG Wielder]

Engine on my 1850HL has begun to cut out at any speed, load or temperature. It's as if the ignition has been switch off but everything stays on, ignition light goes on, heater blower stays on, lights, everything really except the engine. Also though at the same time the fuel and temp gauges go to the bottom of the scale - as if they were reading the wrong way or polarity was reversed. After about 10 mins of checking connections on the distributor, coil and fusebox the engine started again and was fine. Then it did it again a couple of days later. I can't find any loose connections under the bonnet, any ideas anyone?

Thanks for any suggestions.

Interesting problem ! Now that is an interesting bit of diagnostics when you mention the heater blower is still on. This is because of where it is wired in the circuit diagram.
2 options here.
1. Since you have an 1850 HL I imagine this is a late model after WF50,000-odd. If so then the heater motor is wired on the output side of the fused Ignition ON supply. So this means that the Ignition switch and the fuse is O.K. However it is odd that the instruments' readings also drop to zero. Which are on the same circuit. It also suggests the supply to the electronic ignition is also on this fused supply. Which it shouldn't be. It should be on the input side of this fuse where the thick white wire goes.
So can you trace back the main 12V supply to the electronic ignition and see where it goes to. It should be with the thick white wire. It also means that one of the green wires on the output side of that fuse has a bad connection. So as has been mentioned, 2 separate faults.
2. If the car is pre WF 50,000 the heater motor is wired differently. Its wired on the Accessory position of the ignition switch, which means that it could be the ignition switch that is the problem, except you would also lose the wipers.
So next time it happens can you check these plus the choke light / handbrake light / brake lights / reversing lights / please.
3. If the car is a very early 1973 model then the heater started off wired to output side of the fuse as in 1. above.

HTH,
Tony.

[Karlos]

Thanks for the answers, very helpfull.

Had to go out today on a 25 mile round trip. Checked it all over again before I set off, things I noticed:
1. Fuse box gets very very hot with HRW and heater blower on, lots of corrosion and some deposits in the fuse box
2. Feed to the electronic ignition is taken from the 'wrong' side of the fuse
3. It didn't cut out at all on the journey!

So this afternoon I'll look at moving the electronic ignition feed and maybe see about a new fuse box.

[Karlos]

Fixed!

Fuel and temp gauges were dropping to 0 - not going negative as I first thought. When I moved the electronic ignition feed to the other side of the the fuse, the engine did not cut out when the fault re-occurred today. Had no indicators, wipers, HRW, fuel or temp gauge - but the engine kept running.

So I took off the fuse box cleaned it all up and refitted, reconnected everything. Fired up on the button all working fine. went for a run of 10 miles with everything on -lights, heater fan, HRW the lot. Fuse box not getting warm, whereas before it was burning hot.

[Jon Tilson]

Sweet...

its almost always the fuse box....for any dolomite electrical faults.

Jonners