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VP 304 Struggling To Start When Hot

Dysard

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Hey All,

I'm having a bit of a problem with my vp v8, where the car struggles to start when hot. I'll start to crank it over and after a couple of cranks it would almost start and then dies. I'll start cranking again and after about 10 seconds cranking it'll finally start with lots of black smoke pouring out the exhaust indicating too much fuel. I'm not touching the accelerator while cranking.

What could be causing this?

Things I've read so far that could possibly be issues:

  • Coolant Temp Sensor
  • Fuel Reg - Although I would think if this was stuffed it would do it on cold starts as well?
  • MAP Sensor - Again, I would think it this was faulty I'd get the same problem on cold starts?

Also, not sure if related but I think it might be... whenever i flatten the accelerator the engine briefly hesitates, almost as though it floods, and then picks up and goes. It's not missing, pretty sure it's flooding.

Any help would be great :)
Cheers

PS - Also worth noting I've replaced the TPS and IAC and it didn't make any difference.
 

Brett_jjj

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It could also be a leaking fuel injecetor or fuel pressure regulator.
 

88GreenVN

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Check the ignition module if all the fuel system is OK. See if you can test one at a wreckers or a mates when your car is next hot.
 

ybl8te

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interested in this thread - mine is doing the same, thou VN.........how many Km's has your done ? I have 470,000km.....

I too thoughts the injectors were leaky ! So i replace them, engine much smother and using less fuesl, but sadly - still winds over once warm and left for a while. Fuel regulator seems fine to me also....

Would a worn Dizzy (i think thats it) shaft do this ? Thinking also as things heat up, resistance gets higher and being a older car the earth's are getting crappy combined with a 5 year old battery its to much to wind over for the poor old battery ????
 

soop

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Simplest **** first.
Check the rotor cap, rotor button and the coil and go from there. Electrical components hate heat.
 

Dysard

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I think I found the problem. It's the coolant temp sensor. To test it I removed the wire from the sensor, which from my other readings around the web sets the default temp in the ECU to 92 or 96 degrees... hot.

I then drove the car until it was hot, turned it off and turned it back on and it fired up on first crank. The bogged down hesitation when hitting the accelerator is also gone.

I bought a new sensor from Repco just before for $64... not cheap, will install tomorrow and let you all know if it was indeed the temp sensor.

Thanks for all the suggestions and help.
 

Dysard

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I changed out the temp sensor this morning and so far it seems that my problem is indeed fixed.

Just for reference sake I thought I'd point out the following thread(It helped me a lot):

http://forums.justcommodores.com.au...re-1993-1997/153247-vs-5l-wont-start-hot.html

There is also a guide on changing the temp sensor in that thread although I managed to change it without undoing any hoses.
Also, ybl8te, my car has done around 250 000km.

Cheers
 

STEALTHY™

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If that doesn't fix it for good, it'll be the ignition module or the coil. 5L's are prone to killing these because they retain so much heat in the engine bay for so long.
 

Dysard

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I've already had 2 coils and 1 ignition module die on me. I've relocated my coil as well to help it stay cool. Hopefully they will last or a bit now.
 
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