Power loss any ideas please?

yellowz

yellowz

Club Member
My 280Z has an intermittent power loss problem which I can't get to the bottom of.

Every now and then it loses all power and I mean all - no power to the dash, no pump, no nuffink. The car just stops working at all so it must be electrical I think. It has fusible links which I've cleaned up and been through all the fuses in the passenger footwell.

Today it just died on the M4! Not a great place to park on Good Friday :oops: Went through all the fuses - checked them, wiggling everything, no joy no power apart from the hazard lights. Tried it ten minutes later while waiting for recovery, turned the key, lo and behold we have power again. Recovery guy had a laugh with me (not at me) and said 'it's got to be something simple because there is nothing complicated about this car - not like modern s***e'. Followed me home just off the M4 and now the car is fine again.

It has happened a couple of times before where it will not have any electrical power at all for a while and then try it later and it does.

Got me stumped now! Any ideas greatly appreciated.
 
I'm thinking ignition switch?

Do the lights work when you lose power.

Check the spade terminals - I've had one cracked to almost breaking.
 
Check your battery leads are clamped to the terminals properly. Also check the earth lead to where it connects to the body & engine. Any loss of current or continuity will cut your ECU if you have efi.
 
Changed the ignition switch and the back part that goes to the terminal block.
New positive battery terminal put on and both checked tightened down
Will take off the battery earth and clean it up. It does look solid though.
When it goes there does not seem to be any electrical power at all apart from the hazard lights.

Which spade connectors are you referring to Rob?
 
Happened to me twice in a row coming home from SE Z meet roughly the same place as well so both times afte4 about15-18 miles
put new fusible links in and has been fine ever since
 
yellowz said:
Changed the ignition switch and the back part that goes to the terminal block.
New positive battery terminal put on and both checked tightened down
Will take off the battery earth and clean it up. It does look solid though.
When it goes there does not seem to be any electrical power at all apart from the hazard lights.

Which spade connectors are you referring to Rob?
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Just the blade terminals on the switch.
 
I had the same issue. Where is the best place to get the fusible links? I see you can just buy the wires but do you need to change the unit as well, thanks
 
If you’re losing power to the dash - meaning no gauges working or lights - then I would say it’s unlikely to be the ignition switch.

My first instinct reading this was fusible links - but then again all would have to fail at the same time.

So my gut says it’s related to a loose ground connection back to the battery and alternator. Your car should run if the alternator dies or it’s fusible link goes or if the battery connection to positive is lost - so if you blew the big fusible link from the alternator, the engine should still run.

For you to lose ALL power without any fuses or links blown, I would wager it has to be a complete loss of connection to ground somewhere.
 
AliK said:
If you’re losing power to the dash - meaning no gauges working or lights - then I would say it’s unlikely to be the ignition switch.

My first instinct reading this was fusible links - but then again all would have to fail at the same time.

So my gut says it’s related to a loose ground connection back to the battery and alternator. Your car should run if the alternator dies or it’s fusible link goes or if the battery connection to positive is lost - so if you blew the big fusible link from the alternator, the engine should still run.

For you to lose ALL power without any fuses or links blown, I would wager it has to be a complete loss of connection to ground somewhere.
Click to expand...
In my case, the instruments die, then as the fuel pump dies the engine starts spluttering and stops. After a few minutes, I leave the ignition on so I can see when, it all comes back on. It looks like the fusible links have ordinary wire not as per spec. What happens in the fusible link to stop the power supply? and can it come back like that? thanks for your suggestions. It is a 280z converted to carbs with a normal distributor.
 
Thats very weird. The Fusable links just tend to pop when there is an overload on the ignition side/charging circuit. They are a bit more forgiving than a fuse but are designed to pop like a fuse. So maybe somethings getting hot and shorting because they have been replaced by normal wire and when it’s cooled down it’s ok?
 
So it sounds like something heat or vibration related.

Fusible links are not normal wire but also thinner in gauge than the wiring loom they protect, so they are meant to burn out before the wiring loom.

While yours may be ordinary wires that alone shouldn’t cause you issues like that! They would either get hot and crispy or let the loom wiring burn.

What could happen is if they are broken inside the insultstion and just touching until some vibration or heat separates them.

On mine 260z I have 3 links:

1. Alternator to battery and rest of car
2. Lights
3. Ignition

This is why it’s suspicious when you say it all goes at the same times it’s difficult to imagine all three going at the same time. Hence why I’m suspecting an earthing issue somewhere.
 
Huw said:
Thats very weird. The Fusable links just tend to pop when there is an overload on the ignition side/charging circuit. They are a bit more forgiving than a fuse but are designed to pop like a fuse. So maybe somethings getting hot and shorting because they have been replaced by normal wire and when it’s cooled down it’s ok?
Click to expand...
Sorry for repeating what you wrote Huw, our posts crossed in the ether.
 
Thanks guys much appreciated. Intermittent electric faults, particularly when they stop the car! are a real pain!!

I will report back when she goes on the road when the weather stops pretending to be the middle of winter!!
 
My money is still on the earth strap between the battery and engine block/body. A while ago I fitted a cutout switch between those and it went faulty which cut power to everything. Removed it and Fitted a new earth strap and it has been fine since.
 
Mike Bayliss said:
In my case, the instruments die, then as the fuel pump dies the engine starts spluttering and stops. After a few minutes, I leave the ignition on so I can see when, it all comes back on. It looks like the fusible links have ordinary wire not as per spec. What happens in the fusible link to stop the power supply? and can it come back like that? thanks for your suggestions. It is a 280z converted to carbs with a normal distributor.
Click to expand...
Mike
I doubt it’s your fusible links
From what your saying your losing your 12v feed to your pump look to see if it’s using the old injection pump feed
You really need to test the fuse board in the car with a test light when it cuts out to see where power has been lost
its probably your Acc side of the board which is powered by the acc relay from the ign switch .
I think its written on the fuse cover which fused are feed by the Acc relay
 
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