I know this is a long shot.... While I'm rebuilding the engine on my diesel tractor, I decided to buy an inexpensive Cub Cadet locally. It's a 95 2185 with less than 500 hours. It ran fine when I bought it. Did a little cutting until it ran out of gas (too impatient). My boys decided to help daddy by "feeding it" and put grass, etc. into the fuel tank. I vacuumed that out. Then I did a "full service" - plugs, oil filter, oil, air filter, fuel filter, fuel line (all cub parts). When I pulled the stuff out, the old plugs were black, the air filter was completely clogged and the fuel filter had debris hanging out of it. Anyway, I tried to start it....can get it to run on starting fluid but not without. It appears to be getting good fuel flow into and out of the filter, and up to the pump. From the pump, it's decent but am unsure how fast it must flow. this is a kohler v-twin with a vacuum pump (not a fan). Pulled the carb apart, the bowl was a little low but that could be from me messing with it as I pulled it apart. Ideas?????
Check that the vacuum and fuel suction lines aren't hard and cracked, I've seen that on a similar machine. Fuel pump won't pump well if it's sucking air or the pump isn't getting crankcase vacuum.
Yeah, I replaced the vacuum line. WAs hard as a rock. Definitely not getting enough fuel into the bowl. If I refill it, it will run for a little while then starve out. Like not enough fuel more than a no fuel issue. It ran for 30 secs or so after a refill but apply full throttle it dies.
Only line I haven't replaced is the one before the filter. It appears supple, but...?
Weird part is that before the pump, it flows really well. It's after the pump.... And It appears that you can't get a replacement pump?
I have had, and heard of engines that were never the same after running out of fuel when hot. I had one small engine that wouldn't start until the next day after running out of fuel hot.
If fuel and spark is good I would look for a problem in the carburetor.
Pulled the carb apart and cleaned it. Getting air flow past the needle so... It really seems like its flow from the pump but it's such a basic design. It's a vacuum pump and the diaphragm appears fine. No tears.
Those external pumps are pretty universal, ebay "pulse fuel pump". Machines with that type of pump are always a pain to start if run dry, but one it catches it should keep going (stronger pulse at idle on up vs cranking RPM).
The filter is before the pump. I disassembled the pump. It looks ok inside.
Seems the pump is the problem though, I suppose you could try running it on a gravity tank to confirm.
Not a bad idea. Not sure what I'll use as a tank
I've had luck pressurizing the tank just a bit with an air gun wrapped in a rag just to push fuel through the pump and get the air out of the line. I usually pull the fuel bowl and burp the tank until fuel starts flowing then put the bowl back on.
FWIW, this carb has an electric shut off valve. It's clicking which means it should be working.
Did you reverse the fuel lines on the pump? Ya ask me how I know. 
Don't think so but..worth a shot
New fuel pump. Now it has a full bowl and is harder to start on starting fluid but still won't run.
You seem to have fuel, you've had it running before so it has compression, so spark? Fouled plugs? Some safety interlock you're forgetting?
A safety interlock should prevent ignition, right? The only one with the carb is working.
But, wouldn't the fact that it runs on starter fluid mean it's getting spark?
If it runs when you are squirting starter fluid and/or gas down the throat, then you have spark. I would say you have a piece of "food" stuck in a carb passage somewhere.
Starting fluid is a dangerous diagnostic tool, it will light in situations that gasoline won't, either by weak spark or straight up compression ignition (very low octane number/high cetane number). I prefer an old windex bottle with some gasoline in it for this sort of thing, if it won't run on that you know you have a non fuel problem. A bad or forgotten interlock would be all or nothing but fouled plugs could easily run on ether and not on gas.
pull the numbers on the carb and look for a replacement... I went to buy a carb rebuild kit for someone's pressure washer, and ended up buying him a new carb. It was cheaper than the rebuild kit through amazon. And it was prime! I hate carbs, I REALLY hate them on riding mowers.
And this just hit me while I was typing the above. I've got a craftsman mower with that same type of electric bowl interlock carb. I swore I had water in the fuel because it kept trying to die on me. After pulling the carb, and manually draining gas several times, and cleaning the carb out I went looking elsewhere. What I found was that the gasket under the fuel cap had degraded and came apart, part of it had gotten into the line and was randomly clogging it. Was too big to go into the filter. Hit the fuel line with compressed air in reverse through each section and cleared it out. Runs fine now.
I had a similar problem on my riding mower a piece of gravel got in the tank and would randomly block the fuel port on the bottom of the tank.
