how to check the timing on a 1999 mercury cougar?

[Tom]

It just stopped running.I use it for a work car.It is a 1999 2.5 V6.The gas guage shows 1/4 tank still.I changed the fuel filter.While I had the filter off I turned on the key and gas came out but I dont know if its enough pressure to start it.It will hit and barely run if I mess with it enough but it smokes white looking smoke.It had the same problem not long after I bought it and the dealer took it back and had it less than a day and fixed it.He said it was the fuel filter the first time.Would a fuel pump being bad make the smoke white?Usually that means head gasket cracked I know but it was doing it before and they didnt change any gasket?Has any one had this problem or does any one have any advice for me?I dont want to get rid of it,I have nearly nothing in it so I can afford to fix it.I'd just like to try to fix it myself before I take it to a garage. Thanks.