I am having intermittent starting problems with my daughter's car leaving both of us uncomfortable. The car has been running fine until Saturday when it would not start(does not turn over), I found the problem to be a failed fuel system relay. Replaced it all is well until sunday afternoon, it won't start again.

Replaced the relay again, this time no start. Tried the relay in my car and it works so the relay is ok.

While testing the battery it starts. I cleaned battery connections and made sure grounds were solid. Started once but not after that (does not turn over).

I suspect the 8 month old battery had it tested and is fully charged and good at full load, so the battery is OK.

Now I suspect any of the battery cables or connections. My plan is to remove and clean all the battery connections as well as ground connections throughout the engine compartment.

The relay clicks once your hear the main pump for a second but do not get the second click and starter does not turn over.

Am I missing something or is this a good approach? Is there a compound I should apply to the connections to reduce future corrosion?

Should I suspect the starer? It has been working fine.
Thanks for the help. Dan