Electrical fault. engine dies, relay?

[Diongr]

Hi all, not posted before so here goes. 1984 1.9 dg with lpg and elec power steering. been a 6 year project on and off and finaly got it out of my garage to find she will start fine and run for 10/20 mins then cuts out, when I turn the ignition key the dash lights will all come on but turn to start and nothing(loses power to ignition system). Leave for 20 mins then starts no problem untill warm then the same thing again. Any info would be greatful

[Mocki]

Incorrect wiring to the carb heater relay in the engine bay black box?
Resulting in the power being removed once the thermostat is fully open and the heater is told to switch off by the thermo switch ?

[Diongr]

Hi Steve, thanks for your reply. Would this stop the starter from turning? and could it be the relay at fault as the wiring has not been messed with.
If the engine is running at fast idle it seems to keep running but I lose power to steering/dash down to 8v,
will change relay tomorrow and see what happens.

[itchyfeet]

No relay on the ignition wiring
Is your alternator actually charging the battery?
when my alternator died i drove 80 miles home, it would drain tge battery until it conked out then if i waited the battery recovered and it would go again for a while

check the batt voltage when engine running should be about 14v

[kevtherev]

Agreed, battery check needed.
anything less than 11.5 v is knackered

[Mocki]

Sorry I mis understood your description to mean the starter turned and nothing else had power.

[Diongr]

Hi all, new battery last week and when running giving 14v. All runs fine until warm then I lose all power to ignition system and starter, 10 mins later all fine. Going out into the rain now to try and find a solution.

[itchyfeet]

Ignition switch?
try hot wiring it
can pm how if you dont know

[Diongr]

Hi itchyfeet, tried that yesterday all seems ok, right latest finding is that I have 12.4 volts at battery, swich on ignition-no drop in voltage, turn to start and dash warning lights dim and relays click off and still 12.4 volts at battery with no drain. Looking at the hard to follow wiring diagram in the hynes manual where is relay 2, shown in diagram linked to starter solenoid but no mention to location. Is this the one in the engine bay?

[kevtherev]

Clean the solenoid contacts...all of them
clean the gearbox nose earth strap contact.

nice and shiney

[itchyfeet]

Looking at the hard to follow wiring diagram in the hynes manual where is relay 2, shown in diagram linked to starter solenoid but no mention to location. Is this the one in the engine bay?

I find French hard to follow but i dont blame the French its just that I dont understand it

Haynes relay positions are on page 12.4 and its vacant, i.e not fitted not important

[itchyfeet]

Clean the solenoid contacts...all of them
clean the gearbox nose earth strap contact.

nice and shiney

If thats the fault that doesnt explain cutting out
ignition is fed via the ignition switch but with no fuse, the starter trigger is also fed via the ignition switch with no fuse

to me this implies switch or wiring
voltmeters will lie to you, they measure volts but draw no current, you need to measure volrs when a current is drawn.

a broken or corroded cable can measure zero ohms or full voltage, try and draw a current and you find thet are actually high resistance

[kevtherev]

Clean the solenoid contacts...all of them
clean the gearbox nose earth strap contact.

nice and shiney

If thats the fault that doesnt explain cutting out

No I didn't say it does,
but it explains the non start starter as well as the ignition switch

[Ralf85]

Could be knackered ignition switch. They can cause odd things to happen when about to fail. Cheap to replace as a first option before assuming more complex problems!

[itchyfeet]

Can i assume late fusebox
smaller cable from batt goes to fusebox, this poweres almost everything except starter and carb
this smaller 6mm2 red goes to fusebox, check its connections
then from here a 4mm2 red runs to the ignition switch, this powers almost all ignition switched devices, check its connections

From the ignition switch when its in position 2 and 3 12v is connected via a black 1.5mm2 runs back to the fusebox and on to the coil and ignition module via a connector in the black box

also from the ignition switch in position 3 the red/black 4mm2 trigger wire runs to the fusebox then changes to 6mm2and runs to the trigger of the starter

My guess is one of these up to and including the switch is high resistance and heating up, as cables and switches heat they get higher in resistance and voltage falls, it would explain both faults