[jayovnbh]

my corsa 1.2 16v wont start when hot, ive changed every sensor, crank, cts, cam, also changed coilpack, spark plugs.

It turns over but wont start unless its bumped which results in a puff of grey smoke and alot of revving to get it to go. Starts fine when cold and if i allow engine to cool, anyone have an idea what it could be its doing my head in

 

[taurus]

Just to check that the CTS you changed was the one on the water pump, rather than the one on the EGR valve (which is the sender for the gauge.)

Usually failure to start hot is due to the mix being too rich - check the state of the plugs to see if they are sooty or not.

The other thing I've known is a weak battery. I know you think that would result in poor cold starting, but when hot the compressions are higher and it will crank but not quite fire. I've had batteries which will start fine cold but struggle to fire a hot engine. Check the voltage at rest - should be 12.5v, and when running 13-14v.

 

[jayovnbh]

Hi Taurus, yes I changed the one on top of the water pump, new sensor and had it changed incase that one was faulty but still the same problem. It's a new battery I have on the car and I've tried jump leads but still won't start. I'm clueless to what I could be

 

[taurus]

Next time it won't fire disconnect the AFM and see if it makes any difference.

 

[Walksall]

The fact that you can 'bump' start it may be a clue.

If you are sure that the battery is OK, it may pay to double check all the engine electrical connections, including (especially!!) the earth points.

Remember that electricity is 'lazy' stuff, if the connections to the starter are better than the ones to the ignition/fuel system, then that's where most of it will go!

Regards.

 

[jayovnbh]

I've tried disconnecting the Afm no difference, il check the earth points and see if that helps but would a earth only effect the car when hot and be ok when engine is cool

 

[taurus]

Just had a thought - on the fuel pressure regulator pull the vacuum pipe off and leave it to idle for a couple of minutes, see if any fuel starts to spit from the regulator where the vacuum pipe connects. It might take more than a minute for it to show.

 

[jayovnbh]

hi ive just tried that and left it to idle for a few minutes but no fuel coming through

 

[Walksall]

A couple of points:
Resistance can in fact increase with temperature - and you don't need a lot of it to cause trouble!!

Were the new sensors genuine GM ? if so, they SHOULD be OK - if not, who knows?

Regards.