Engine runs cold, dies warm...

[rogerc84]

Any suggestions on a puzzling engine fault just started with 1984 2.0 litre 924, resulting in a Relay home?
Last Friday :-
Engine wouldn't fire on first turn from cold ( normally good).
Fired, just, and then caught on second turn.
Run happily for 5 miles, then the engine slowly dies ( like fuel starvation, though tank is half-full) and we roll to a halt. Won't start.
Change the fuel pump relay( always carry spare), check fuse, but no joy. Check getting a spark. OK, but...
While waiting for the AA, try again .
Engine starts, but dies after a few seconds. Wait for ten minutes and same thing happens - it fires, sounds healthy and then dies after a few seconds.
Finally relayed to local garage( closed) in village. After Relay left, decide to try again.
A healthy start, healthy running.. ..decide to dash for home half a mile away and make it OK. Turn off. Try starting again. No joy.

Previously - One instance of non-starting traced to broken, not blown, fuse. Occasional problems on re-starting hot recently - like one cylinder catching and others taking time to join in.
Fuel pump(s) is old, could be original ( 94k miles), but sounds as if it's working.

My local garage will do the job, but it would be good to have some pointers for components to test first. It sounds more like a fuel supply problem. I have checked previous posts, but problems tend to be with cold starting rather than warm dying. The Relay driver said his father had a 911 with similar problems, traced ( after expensive investigations) to a loose wire. How reassuring! Any ideas which wire I might waggle??!!

All suggestions gratefully received. I must positively fix the fault now before attempting any journey more than half a mile, just in case it all goes dead again in the middle of nowhere...............

 

[924nutter]

if you can hear the fuel pump, and it sounds any louder than a faint sizzle then the pump could be tightening up. One of mine did, and damn near melted the relay wires to destruction. Check the insulation where the relay plugs into, to see how hot it has been runing. the signs will be obvious, but this is usually associated with a misfire when accelerating as the mixture goes to pot due to insufficient fuel pressure. My thoughts then turn to the igntion coil, whose windings are breaking down as they heat up; this is simple to check out and not uncommon. In the short term almost any known good 12v coil will work long enough for you to satisfy yourself that the coil is either at fault or good. Try these simple things first.

 

[rogerc84]

I was pretty confident I could depend on you for some good suggestions! Yes, the pump does drone but as this has been a characteristic for a long time I have perhaps not given it the significance it deserves. The coil is an interesting one and well worth a poke.
When I changed the fuel pump relay on the road I wasn't aware of anything untoward around the relay board, but again it's worth re-checking.

Many thanks. I'll report back on progress for communal benefit.

 

[rhitchcott]

Regarding wires, check the yellow loom behind the engine - replaced mine for some reason some time time ago - I was told it was a bit burnt and it could give starting problems if I didn't replace it.

 

[rogerc84]

The problem seemes to have been solved. The relay and relay board were fine. Neil at the garage investigated the fuel system. The lifter pump in the tank was OK, but he replaced the fuel pump ( I've had a spare waiting anyway for the past twelve months, just in case of a problem) - and the fuel filter. The latter had been done early last year about 5,000 miles ago, but it meant the main parts of the delivery system had been renewed.

The car operated fine on his test and has been OK with me on two 20-mile journeys in the past couple of days. (The fault had developed after 6 miles from cold). I am hoping therefore that it has been a straightforward problem which the work has cured, rather than some kind of intermittent electrical fault which might yet return. My confidence improves by the mile.

The new pump makes hardly any noise and there seems to be an improvement in smoothness and security of engine response. As the old pump was probably original and was quite corroded on the outside, I am minded to put the fault down to simple old age, but then I'm beginning to recognise how it must feel..

Thanks to respondents for your suggestions - they were all thought-provoking and useful. By the way, if anyone finds they have a car problem in South Devon I can recommend Neil Gillard at Gillard Motors, Loddiswell on 01548 550112. It's a small repair and maintenance garage but well-equipped, knowledgable and very helpful. Naturally I have no connection other than as a satisfied customer.