Sometimes my startup will crank for maybe 10-15 seconds longer than normal. It only happens occasionally and it seems to be when the fuel tank is low (maybe a coincedence?). Also, I resoldered my main relay and the problem has happened before and after that. Other recent work i've done: new plugs/wires, distr. cap and rotor, replaced lower rocker arm seals, fuel filter.

 

It could be a keyswitch problem. The keyswitch faultcan appear very similar to failed main fuel relay. Only way to know is to look for instrument panel lights when you are having a hard start. If no panel lights, the problem is likely the keyswitch. If lights are on, the fuel filter and fuel pressure regulator are potential problems.

good luck

 

Could it also be a problem with the coil or igniter?

 

Coil and ignitor don't tend to be intermittent, but it's certainly possible. Since problem doesn't really exhibit for any length of time, it is very difficult to determine whether fuel or ignition is the problem. You might perform some general maintenance, if the plugs, wires, rotor, and distributor cap have not been replaced recently, or simply wait till problem becomes continuous to diagnose.

An easy one is to look for instrument panel lights when hard start is occurring. If panel lights are off, the keyswitch assy is very likely.

good luck

 

Another way to tell is wiggling the key in different ways when starting. If you can make the problem happen simply by holding the key in a different way, then it's probably the switch.

For example, if it's not starting, try again but don't twist the key all the way to start. Just twist it barely enough to get the starter to run. Or maybe push on the key up down or sideways to see if that changes things.