I have a 93 Honda Accord. It has starting problems, so I looked everything up online and it came down to the main relay, so I switched the main relay with another used one (from junkyard), it worked, drove it around the block, came back shut the car off, then tried to restart, it wouldn't fire up. So I waited next morning to start it up, same thing wouldn't fire up. So then went to the junk yard and got two more main relays. Tried another relay, started for a little bit then died and then car won't start any more. Don't want to use up the last relay if something is causing it to short. My question is, could there be something that is shorting out the main relay? ps. I also try resoldering the thing, didn't work.

 

main relay problems usually occur after the car has sat in the hot sun and has hot interior;
After all your relay swaps I'd have to say you need to look elsewhere for a problem.

Can you hear the fuel pump run for a few seconds when the key is turned on?
12v Power at the Black/yellow wire at the dist plug with key on?
Spark at plug wires when cranking?
use a screwdriver as a stethoscope to listen to injectors when cranking
Be sure the ground connection at the T-stat housing is clean and secure.
How old are the spark plugs?
Any main't ever been done?

 

Why would you buy a main relay from a junkyard in the first place?