!993 Taurus SHO cranking, no start

[Louienor]

There is no rhyme or reason to when my car decides to do this. The only time I know it will definitly start is first thing in the morning, other than that it is a crap shoot. I took it to the Ford dealer and they said it was the crankshaft sensor, so they replaced it. Able to start the car 4 times, on the 5th try same thing. ALso, now the blinker is only working when it feels like it. Ford says that was the only code that came up when diagnostic tests run. I of course need to take it back today, but they seem to be at a bit of a loss, and I am upset about paying alot of money to fix something that doesn't appear to have been broken. Any ideas on what causes a problem like this?
The car has 84,300 miles on it, seems to be in great mechanical condition other than this (so says Ford).

[shorod]

Welcome to the forum!

What you'll need to determine now is if the cause of the no start condition is lack of proper air/fuel ratio, lack of spark, or lack of compression.

Since the car starts sometimes and seems to run fine, lack of compression and lack of air is probably not the problem.

See if you can find a fuel pressure guage and measure the fuel pressure when the car won't start. If you don't have access to a fuel pressure guage, then check for spark by using an old spark plug and laying on a grounded part of the engine.

The crankshaft sensor was a common item to fail on the SHO when the water pump leaked. If it is faulty, it could cause a lack of spark.

A failing fuel pump could also explain they the car seems to work fine when cold, but fails as the pump warms up.

-Rod