I have a 2005 Honda CRV with roughly 170,000 miles. Check engine light would come on at different times. Auto zone code came back as a knock sensor. When starting after setting a few hours car would be hard to start making you think bad battery or bad alternator. Car has new battery and alternator has been tested. Both good. Replaced knock sensor, replaced blue fuel pump relay in glovebox. Still happening. Seems to help giving car gas when trying to start. Any ideas?

 

A couple of things might be happening, ...

The fuel pump puts gas into the line to prime the fuel rail of the injectors
This happens when the key is first turned to the on position
Your vehicle may not be doing that.

Turn key to on position and then back to off and then back to on
Do this a few times then try to start engine.
If it starts easily then pump is being turned on and priming the rail
There probably a lost of pressure while it sits
If not then need to check to see why it is not

Assuming it is priming fuel rail, that would mean a couple of things
One could be that one or more injectors are sticky or stuck
(could try putting a bottle of fuel injector cleaner through system??)
If stuck open then it would take longer to start cause it is harder to put enough pressure into fuel rail
Or two, the fuel regulator is not holding the fuel pressure and releasing it while it sits before the next start.

These are just possible causes.
There may be a few others.
Good luck tracking it down

 

Thank you, will check those. Had to pick daughter up last night from work because it won’t turn over now. Have lights and sounds and those are all strong.

 

Did you ever find the problem and get it fixed?