Sudden fault...

[tref]

Damn, just back home courtesy of the RAC...

At about 60mph, engine died, would not restart. Engine cranks normally, apparently no lack of compression. Tacho needle bounces on cranking, so presume crankshaft sensor ok... backed up by the RAC checking for a spark. We have spark. DME relay changed as well. Fuel pump can be heard to run on cranking as usual, and after winding the car up the drive on the starter motor, a strong smell of fuel, suggest fuel going somewhere!

Now here is probably the most useful hint at what it could be... on cranking, it doesn't even try and fire, but it has "coughed" a couple of times at the end of cranking. This leads me to suspect the ignition switch, but if that were the case, I would expect it to start, or try to run whilst being cranked, and stop when the switch is put back to ignition only rather than ignition/starter?

I suspect it to be an electrical fault, as there was no misfiring, just a clean "stop".

Any suggestions?

At least it is a clean fault, rather than an intermittant problem!

TIA,

Tref.

 

[Fat Albert]

Hmm, I am not sure, but I have a similar thing sometimes whereby the engine cranks happily enough without firing, but then starts as soon as I release the key.

Strangely the aircraft does the same! That is down to the fact that the Magnetos retard the timing between certain rev-ranges and our starter and battery are too healthy and crank the engine too fast!

 

[tref]

OK... I'm not so sure Ihave a spark all the time (The RAC guy told me I had spark) I think I am only getting a spark at the point when teh ignition is turned off...

I have, however, also tried jumping the connections to the ignition switch terminal block - i.e., hoping for it to run and prove the ignition switch at fault... no difference, so I suspect the ignition switch is ok.

So back to square one... any ideas?

 

[tref]

OK... This is NOT the way to fault-find... but because I had one, I disconnected the ignition amplifier, and connected in the new one I have. Car starts Running as rough as hell, but I suspect that is due to the fuel which has been pumping into the engine whilst it hasn't been starting. I didn't want to run it for long, as it isn't bonded to the heat sink.

So... add that to the knowledge base for when 944s stop working...

Meanwhile, any suggestions of what I can use to bond an electrical component to a heat sink reliably, given I'm not an electronics bod, so don't have any of the proper stuff...

Copperslip? Grease? Toothpaste? Actually... I think I'll wait until I can get to Maplins and get some of the proper stuff! No point in wasting a £70ish component for the sake of £2 worth of gunge...

 

[bmnelsc]

Copperslip? Grease? Toothpaste? Actually... I think I'll wait until I can get to Maplins and get some of the proper stuff! No point in wasting a £70ish component for the sake of £2 worth of gunge...

Good call....probably the same stuff used to stick a heat sink to a computer CPU....Hmmm...Or similar - computers aren't exposed to oil or damp [8|]

 

[robdimond]

If you need to bond the component to a heatsink, you want a 2-part thermal epoxy:

http://uk.farnell.com/fischer-elektronik/wlk-5/adhesive-thermal-conductive/dp/1211723