Engine Dies After Warm Up

[hedgerley]

My 2001 V8 is off the road at the moment. I've kept the trickle charger on and every weekend or so start her up, run up to operating temperature, switching off after 10-15 minutes when its all warmed through. All was well until last weekend. Started immediately, fast tick over as usual, settles down to the correct idle and gets to its usual temperature. Then, after 10-15 minutes, it started spluttering, running unevenly, idle got slow and erratic then it just expired with a phut. Runs and revs nicely until that point. Repeated exactly the same, yesterday. Until I SORN'd her she's never light me down as far as the engine is concerned, in 14 years of ownership.

Plenty of fuel (recent top up, so should be good) and no warning lights. I suspect its electrical. The alternator/charging light doesn't come on but when the spluttering starts the rev counter starts behaving erratically and the speedo starts twitching. A minute or two before it expires the tacho drops to zero, even though the engine is still running.

I haven't dug out my voltmeter and tools yet but thought a quick post here might solicit some guidance. Thanks all.

[Bibs]

I'm not 100% sure on the V8 Esprit but that does sound like a battery which can't hold charge any more. There's enough in it from the trickle to start the car, but it takes a hit on turnover and descends to dead so can no longer supply enough charge to spark. If the alternator is sending enough charge despite the battery not being able to hold it, the light won't illuminate. Pop a volt meter across the battery and I'm sure you'll see a rapid discharge after starting. 

[Barrykearley]

A very common issue is also Earth straps to the engine. I’m sure there’s a post about this - Swindon Alan had this with his.

can be proved or disproved by using a jump lead from the -ve block of the battery direct to the engine.

[hedgerley]

Thanks both. I suspect it's the battery. I've just remembered something similar happened on my Volvo a few years ago. Battery was knackered.

[Espritv8black]

If you test the battery with your volt meter and it is fully charged it should show 12.8 volts, you can of course while running also put the volt meter across the battery terminals and it should show 14+ volts to show the alternator is charging.  Hopefully just the Battery, cause to get to the alternator.....well you know more work.  I had my alternator rebuilt a few years back and was very happy with the results.  Also had the starter rebuilt, it was always slow to turn the engine over and that made all the difference in the world!!!!!  Each rebuild here was about $125 USD.

My guess, the more I think about it is that the Battery is OK or possibly weak and the alternator is not putting out enough juice to keep the car running and also charge the battery.  If the alternator was OK the car would run without a charged battery.