If a four stroke gasoline engine (inline-four, digital fuel injection) starts with starting fluid (but not without it, and stops firing when the spray is removed), is this an indication that the spark plugs are working and that the timing of the sparks is correct?

Or, is it possible that the starting fluid is simply auto igniting due to compression alone?

I see on the Wikipedia article: https://en.wikipedia.org/wiki/Starting_fluid that the autoignition temperature is low, at only 160 degrees C.

I imagine this would depend on the particular starting fluid. But even if it does depend on the particular starting fluid, can some statistical answer be given? E.g. that "in most cases the starting fluid will start the engine even when all the spark plugs are non-functional".

  • 5
    In my experience if there's no spark starting fluid won't ignite in the cylinder.
    – Ben
    Jun 4, 2016 at 12:32
  • 3
    If an engine starts and runs with the aid of starter fluid, but not without, I would turn attention to the fuel delivery system. Clogged fuel filter, bad fuel pump, clogged gas tank, etc.or possibly the fuel for contamination. Jun 4, 2016 at 14:28

1 Answer 1


If the engine is cold, there is no way the combustion chamber is going to get up to 160 degrees C. even when the air is compressed. So your problem is with the fuel system; either the fuel pump, or something in the fuel injection system.

  • Can you explain why 160°C temperature is important in this case? Make it relevant to the question. Jun 4, 2016 at 17:08
  • 1
    The OP quoted the Wikipedia article mentioning the 160 degrees C.; I'm just pointing out an engine won't get that hot unless it has been running. Jun 4, 2016 at 23:26

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