Second generation Coyote. When cold, it will crank and crank and crank. 20 seconds +. Then as it catches, it will backfire and spew a fair amount of smoke. I mentioned this little challenge a few weeks ago in my go-kart thread. At that time, I thought my fuel pressure was too low. Not so. I checked the pressure while the engine was running and it was over 80 psi. I lowered it to between 55 and 60. (spec is 55, I believe) No difference.
This is a relatively new problem. What changed? I didn’t have the vacuum lines or PCV connected before. They are now connected via inserts into the air intake elbow. I also have new fuel lines (3/8 feed vs. 5/16 originally). I can’t see how a vacuum line or a crankcase ventilation line would have an effect, unless there is something screwy going between those plug-ins and the MAF sensor.
So, in my (limited experience) mind, these are the possible causes:
1. Lack of fuel / fuel pressure. Toward that end, I checked the pressure (see above). I have tried cycling the fuel pump two or three times prior to engaging the starter. No difference.
2. MAF sensor issues. Haven’t done anything to it, except install the PCV and vacuum connections on the same elbow. I haven’t heard of others having this problem and I know I’m not the only one to install these in this spot.
3. Clogged injectors or clogged fuel filter. However, these are all new parts. If the injectors were clogged, they wouldn’t smooth out and run – I have to believe it wouldn’t even start. Upon start, idle is 1200 rpm and then it settles down to 1000 and lowers a bit more once the fan kicks in.
4. When it does catch, I get a backfire – usually on the passenger side – and a fair of smoke. Could it be too rich a mixture? That would point to the MAF, no?
I’m considering unplugging the MAF sensor and giving it a whirl this evening. Any other thoughts, ideas, suggestions, or humorous remarks?