So, as the title says, my Miata won’t start when it’s hot. The engine keeps turning over but doesn’t catch, and I have to let it cool down for about 20 minutes before it will turn on again. When it does turn back on, it blows a ton of white smoke out the back and I can smell gas for about 5 min afterwards. I have replaced the spark plugs and the wiring for them, and the problem is still there. Ideas?
Also, I can bump start the car with little to no difficulty. It runs ragged for a few minutes then it runs great. So I have no idea what’s up. Help?
Normally, white smoke is a sign of burning coolant and the main suspect is usually a head gasket.
However, it’s possible that a leaking intake manifold gasket could cause this also. I think coolant passes through several places on the intake gasket and it could be that what is happening is that the hot engine with the cooling system pressurized is weeping coolant into the motor and causing a flooded condition.
If there is no coolant loss (and it doesn’t take much to cause a problem) there’s always the possibility of a leaking fuel pressure regulator. The regulators can be easily checked by removing the vacuum hose and noting if there is gasoline inside the hose and by trying to pull a vacuum on the fuel pressure regulator diaphragm. It should hold vacuum.
That’s the things I’d consider and hope it helps.
(I would add that if coolant is entering the combustion chambers the tips of the spark plugs should reflect that and should have a glazed and/or whitish color to them.)