Easy to start cold, but hard when warm?

Not always easy without seeing vehicle Remove spark plugs and look at the colour, and if they are warn out. The part shop will know if they are warn out if you cannot get any help from friend etc. But if in doubt they can still help the running of the car for a small price. They are cheaper than an hourly mechanic fee. The colour should be just a very light brown, but not black and oily. Place 1 sparkplug lead onto spark plug and with the s/plug resting on a metal part of the engine. turn the engine over with key, as if you are starting. ( you will need some one to help while you look.) And look and see if their is a health looking spark. Weak no good but if it is just looking bright it probable is OK. Even buy one sparkplug and try this to compare spark if you do not want to spend much money, or borrow 1 sparkplug. To compare spark by sight it does not have to be the same number as you are not fitting it to car , but the spark from 1 plug to another will look the same. If plugs are black change them, and look to see if the choke is working, going on when cold and off when hot. Most of these things it probably will not be , but you just have to go through the procedure and eliminate every thing as you go. Make sure all battery leads and connections are clean and not corroded. But you should know that if the motor is turning over fast or slow. But if you are doing it your self it is then cheap , and remember everything can help. When the car is a 1987 you have to check most of these thing anyway with a normal engine tune up. So if you do not do it the mechanic will check them all anyway, except you have to pay for it.I have had cars that start cold but when hot no start , and just connections. Yes if it has ignition point they may well be dirty, and if spark weak the condenser may need replaced. Depending on the ignition system, weather it is points or electronic.Their is many reasons why some cars do not start. The spark plugs leads also can start breaking down. A ohms meter will tell you this. Some of you friends or you may have one of them. they are cheap anyway.Check your car lead ohm`s readings compared with another car leads they should be similar.hardly two cars are faulty. As you do not need to replace if not needed,.These things are just normal things to be tested for such problems such as hard starting. Sometime it can be the most un obvious thing . that can be over looked. But to a trained eye most thing are not difficult, but don`nt be fooled. even the best can have difficulty with certain faults. When the air filter hose is off with a torch look down the carburettor and when you move throttle see if their is any fuel spraying out a small accelerating pump jet. If all thing fail buy some Spray Easy Start, and spray down the carburettor when hot, if it fires only or hopefully starts., to me it would tell me that the ignition is all OK as it fired ( if it did not fire then could be ignition trouble as it should at least fire with Easy Start - as the easy start is then the fuel so should ignite. So if It fires but not start to me it tells me it must be fuel problems. It is all in, correct diagnoses, procedure. Could be fuel block in line filter but would not think so if when driving you have no problems. Normally fuel block lets you know when you are powering up the road. But look at in line fuel filter if 1 is fitted. Never heard of radiator cap stopping starting , but who knows what god will do if you are misbehaving. ( but not a god believer, but for those that are who know`s ) I am a mechanic and are 61 years old. So have many year`s experience. But can not bet looking at the car physically my self. And as you knows every one knows better,after the problem is fixed. But while you are doing it they are not to be seen. Hope this helps.Good luck.