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Evening all, struggling with a bit of a weird one. Recently picked up a NBFL which has been sat parked up for a year.

I thought I'd give it a full service and got to doing a coolant flush and that's where I've run into a peculiar problem.

My car idles really rough and then dies when I turn the heater on full, but only after it's been warmed for a while. I managed to do two cycles of draining the radiator, filling it back up, running the car and turning the heat on when it was warm before it died.

The car then won't start for love nor money and all of this has happened twice now with the exact same pattern. The car has a new battery, new cam angle and crank position sensors, new belts, new plugs, and new oil. I am shocking when it comes to checking the electrics (pun intended) but could do so with some guidance.

Has anyone experienced anything like this before or could point me in the right direction? My research thus far has led me to ordering a replacement ignition switch in case that's the issue.
 

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You can run the heater fan with the engine not running. That's what I'd check first. Turn on the ignition but don't start the car and see how the battery voltage drops as you turn the fan up.

In fact even before doing that I'd check the main drivetrain ground is intact (Battery ground cable end is fixed to the powerplant frame. Look under the car in front of the right rear wheel and you can see where it bolts on, just beside the diff. They're notorious for fracturing there).
 

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Would a weak alternator stop it from starting up again? I've borrowed a multimeter but haven't got the foggiest on how to check the alternator with it
When it doesn't restart what does it do? clicking? slow turn over?

Simplest check is get your multimeter, set it to DC voltage and put the red probe on positive terminal and negative on black terminal DC volts have a V symbol with a --- line and .... above it.

If its a less fancy one youll want it on 20 (which means itll read up to 20 volts DC)

Make sure you have the leads it the right holes, if its a normal multimeter it will have three holes. Centre is common and the right and left are changable. For volts youll want the right hand side one which will be marked volts. Normally the left hand side spot is for current only

(black lead always stays in the "COM" (common) spot in the middle. If you are just measuring voltage you can't do too much harm unless you touch the exposed probes together and short things.

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