When cold especially, I crack to start it is very slow and sounds flooded and a toooonnn of unburnt gas smoke comes out the back and it sounds like a ported engine in open loop.


When it’s at operating temp and I turn it off and immediately turn it back on it has no issues starting and sounds fine, give it a minute or two and it refuses to start and you can smell the fuel pouring out of the exhaust.


Ive replaced coils plugs and wires to no avail, and swapped mafs with no luck either.

Fuel trims are perfect when running and on shutdown. I can’t see cranking afr because it doesn’t use the o2 sensor.

cranking RPM is around 250 and it doesn’t start, but right after I shut it off and start it again the RPM is about 350 and it fires right up.

compression was tested and good a few months ago @ Mazda.

Couple people I met said leaky injector and that makes sense but I still feel like that’s not it. Any advice or anecdotes would be all appreciated.

 

Poor cold starts can point to coolant seeping into the combustion chamber while the car sits. Are you sure the smoke is fuel and not coolant? Are there deposits on the spark plugs and/or is the coolant level slowly going down?

 

Positive it’s fuel, it smelled like a gas line ruptured when it first happened... and it’s not like coolant smoke. I’ve had my experience with that in the past...

Spark plugs looked normal R1 Trailing had some carbon deposits on it but it looked normal for their life, the electrode was clean.

 

It does sound like fuel is pooling while it sits then. Could be a leaky injector, you can try running a tank of gas with seafoam or similar gas treatment to see if that cleans it out. Not sure it will help but it's cheaper/easier than any intervention, worth a shot.

Give it a nice workout if you're confident everything is working well apart from that.

 

Update:

I can get the car to start up pretty quickly when it’s connected to another cars power supply. I replaced battery (free anyway why not…) and no avail.

I’m getting a compression test done first ($80) before I look at starters or anything else more destructive.

cranking RPM with gas pedal on the floor (fuel injection cut) is 238/240rpm.