I have a 2007 Mazda 5 1.8 petrol with 81K miles. Sometimes it takes long to crank but sometimes it starts fine. Already changed the spark plugs, oil, filter, the air filter is clean. Why can I that be?
What about your fuel filter? Is fuel pressure OK? Is the fuel system holding static pressure when the engine is turned off?
@chucktobias Thank you for the fast response. Do you know by any chance where fuel pressure valve is on my car? Apparently it’s on the fuel rail but I can’t see it there.
I'm not even familiar with the U.S. version of that car, let alone the UK version which is what I assume you have due to the engine size and usage of the term 'petrol'. Here in the U.S. the 2007 Mazda 5 was equipped with a different engine, 2.3L. The link below shows how to check fuel pressure on the 2.3L engine but yours is probably different:
Try cleaning the throttle body and throttle plate with throttle body/carburetor cleaner.
Check the battery voltage and alternator voltage output.
The starter may be beginning to fail.
@avalon04 Thanks for the reply. The last time I checked the throttle body and the plate were clean and the battery was fine too. Is there a way to check the starter motor without replacing it?
If you're engine is spinning over without issue and even if this is an intermittent problem, a no-start issue is typically caused by a lack of spark or fuel so the same tests generally apply. The FAQ has a section on crank, no-start diagnosis with videos here: https://carkiller.com/scottykilmer/qa/nostart/#post-54875
