1985 Chevrolet Suburban wont start

Take a plug wire off on the drivers side and crank it over with the hood up. If it's getting spark you'll hear it popping as it arcs on the engine

Yes it has spark. Battery is fine. Fuel filter is good. Fuel pumps trough line when diconected. Filter is good, replaced last fall.

Ok. Good. Did you check for fuel at the filter or the throttle body? The injectors may not be firing. To verify, spray a little carb cleaner or dribble a little fuel into the throttle body to make sure its a fuel problem. If it still doesn't run, how old are the plugs and wires?

Fuel is getting in to carb. Plugs wires rotor cap replaced last fall. Ran fine all winter here in cold minnesota. It did back fire once a couple weeks ago after shutting off.

Ok. Well somethings missing if you've got air fuel and spark then you've got it all unless theres a timing issue or not enough compression. It might also be that even thought you have spark you don't have enough spark. Your coil might be weak. Which, if any of these, are you comfortable trying to check?

Yes

All

Ok. Well if you've tried the starting fluid or carb cleaner or fuel in the throttle body then we know its not a fuel issue. When you saw spark at the plug was it a little tick or a nice bright flash. It should be the flash. That could mean the coil. Also take the cap off the distributor and then take the plate off that's under the rotor and the rotor. Look at the inside parts of the distributor. Are they rusty? This can also play a big role in misfires of lack of spark. Take all the plugs out and rent a compression tester at the local parts store. It just crews in the plug hole and then you turn it over to get your psi of compression on the gauge, it should be 150 with no more than 30% variation between any two cylinders. Look under the cap at the points, are they green and fuzzy looking? And check for vacuum lines going to the distributor for a possible leak or break. The big plug under the dist cap is for the ignition control module. They sometimes like to break wires at the plug. Check that too.