hard to start

while having no problem starting first time for the day, my trooper has developed problem starting once the engine is hot (driven at least for 20-30 minutes)
what's odd is that even if the first engine start occurs late afternoon, it starts fine, although with low initial revs (at 300 to 400 rpm) but at least it starts, after that, it may take 12 tries to get started
there's no problem cranking, starter is almost new and alternator is also new
so far, have changed plugs and the fuel filter but have not emptied tank (in case of a bad batch of fuel)
any other simple things I can look for? if suggesting an adjustment, kindly provide a little more information (ie. if you suggest to turn humdinger counterclockwise while aligned toes to the north pole, I will likely get the toes part right while not locating humdinger)
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i have come across electric fuel pumps weakining after warm up ....and also fuel line vapor lock......also check your crank sensore and cam sensore ....sometimes also old or worn throtle sensores sometimes will not get a good conection inside and you can press the foot peddle down JUST ENOUGH to move the position ..i am talking 1/16 of a inch or even less....and also the start up circut could be breaking down after warm up ...hope this helps
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rick wrote:

Can you describe the colour and general look of the spark plugs when you took them out?
--
Howard Neil

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Howard Neil wrote:

they are always a little dark, electrodes are clean but the trooper DOHC 3.2 engines always flood a little engine oil since the plugs sit fairly deep and I've changed the wire harness a couple times into the new style which seals the plugs a little better
will probably replace charcoal canister, o2 sensor, egr valve
what parts of the fuel system would you check first if you had to replace a few sensors, adapters etc? (fuel filter was already replaced)
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rick wrote:

I'm afraid I don't know enough about the Isuzu petrol engine to comment on the sensors, etc, as I have a diesel engine in my Trooper. I was just hoping it was something simple like too rich a mixture (plugs would be black and sooty). That would certainly give hard starting when hot. The only other time I have known a hot engine to be hard to start turned out to be a cracked plug but you've already changed yours. Sorry, I have to give up.
--
Howard Neil

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Howard Neil wrote:

well, that does fit the description - is there some easy/quick adjustment for fuel mixture?
it's the 3.2 liter DOHC engine
wait a minute! is it as simple as perhaps just replacing the oxygen sensor?
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rick wrote:

I don't really know. As I said, I have a diesel Trooper. If it is running too rich, you really need someone who knows your engine to suggest your options to weaken it.
--
Howard Neil

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