Hard warm starting

Starts well from cold and likewise hot start (left for 10 minutes parked and engine up to temp.) but warm start i.e. left for an hour or thereabouts requires 5 secs of starter motor and then very reluctantly fires up. No performance issues when running, pulls like a train, idle is smooth and there are no codes stored.

I changed the water temp sensor which has put hot start on a par with cold and the thermostat operates correctly but warm start is still a pig.

Could it be coil packs on their way out? Last plug cut showed a bit of soot on the plug bottom, insulator clean but I also get a bit of soot on the tail pipe after a 20 mile run, is this normal on the Coupe?

Any advice welcome, Thanks

Car details, mileage etc could be handy Clanger?

Yeah agreed

20VT 1999 123k miles

Crank sensor or yellow connector of death.

Thanks for that.

I also suspected the crank sensor as I have seen it go faulty on 2 other Italian vehicles from the 90's however the nature of the failures lead me to rule it out in this instance. But with you saying that, for £25 delivered I think I will just change it.

I still have not figured out the YCoD. Is it under the dash near the drivers right knee?

YCOD is next to the fuse board right hand side under the column, it's a connector 40x20 with a green/black wire and a thinner pink or orange, usually just these two wires and the green/black is the main feed to the fuel pump so it's prone to burning out the connection inside the plug causing it to be an intermittent supply sometimes.

Brilliant, thank you very much.

New crank sensor, YCOD removed, wires crimped and soldered together problem still there. Good strong cold start, better than before but after long run and hot engine, left for 45 minutes difficult start remains. Catches after about 5 seconds of cranking but slow to catch and build up revs to idle.

Will try a plug change but any other advice welcome.

Ta

Maybe multiple injectors failing at once.

For anyone reading this in future; I constructed the fuel injection leakdown tester as described in the manual and have traced the problem back to leaking injectors or injector. I need to replace the inlet rubber doughnuts so will check which or if all are leaking then.

The problem sounds similar to a lhd coupe I owned,turned out to be the inlet doughnuts.