Re: Hard starting when Hot

Posted by HH56 On 2017/4/6 18:49:29

As O_D said, old coils seem to be the usual culprit with that no start or intermittent dying when hot problem but I seem to recall someone else having a similar issue not too long ago. Believe his turned out to be the condenser. At any rate, if the fuel checks out OK, condensers are cheap and you can pick up an IC-7 from Napa which is a universal 6v coil many of us use..It is good to have a spare of each anyway.

Another question is how does the engine turn over when hot. Is it moving at about the same speed as when the engine is cold? If so, most likely the coil or condenser but if it is turning over much slower when hot then I would wonder about the condition of the starter and if adequate voltage and amps are there. Electrical conductors increase resistance when hot so if the starter is getting heat soaked or needing to pull a lot of current moving a hot engine the voltage available at the coil could be dropping down enough that the spark is no longer sufficient to jump the gap.

You might check the voltage to ground on the coil terminal coming from ign switch while the starter is cranking the engine when cold and then again when the engine is hot. If there is a significant difference between the two tests or if it drops below about 5v the available spark may not be adequate. A large voltage drop would point to the starter or too small a battery or battery cable, or dirty or loose connections. Any of those problems could be the cause of the non starting.