Just like the title says, I have a janitrol gupi 100-4 that will power up, and ignite for 5-10 seconds, but the burners? Will not light up. Not sure what to check, any advice?

Clean flame sensor if so equipped. Then check to see if 24 volts is being applied to the gas valve during the start process.

I don't see any kind of sensor in there. I have plenty of juice, and a big (1-1.5 inch each side) ignition flame coming out for 10 or so seconds. Seems like there is no gas going into the "tubes" for the ignitor to light. Sorry I don't know any of the names of these things.

Then check to see if 24 volts is being applied to the gas valve during the start process.