I’m stumped at this point. Working on a friends riding mower for him trying to get it back up and going.

Replaced all fuel lines, fuel filter, carburetor, fuel pump, spark plugs, air filter, new gas and sea foam. Still won’t run unless I’m feeding it fuel. It runs as long as it’s got fuel but even after replacing all this, nothing. Any ideas because I’m stumped?

Completely close off the air intake while attempting to start it. I don’t mean close the choke I mean suffocate it with something. Zero air. This should fix you up.

Nope tried that already. Or best I could with the size of the opening. Confident enough to say it closed it off.

So, run down why fuel isn't getting to the carb. Because clearly that is the problem.

My Miller Bobcat would not run on anything but starting fluid. Two months after a customer loaned me some gas he said was ethanol free.

Fuel was getting all the way to the carb. Replaced the carb and all is well again.

Guarantee that damned ethanol stopped up the jets.

If you have fuel flow, air, and spark, then my vote is a bad carb. And I once installed a new carb but incorrectly installed the gasket. Ran great when I got the gasket on right.

I’ll have to double check the gasket now. Making me second guess that thought.

One thing I did notice, I feel like the fuel line may be smaller than what came off of it. Couldn’t be much and of course the old line was years and years old so no telling what size it was.

You've verified fuel is flowing To the carburetor, correct?
If it's your run of the mill, Kawasaki,Briggs or Kohler, should be 1/4 I.d. fuel line.
Did you purchase a OEM Carburetor or Aftermarket ?
I've bit the bullet on the cheap ones and I'd say they're 50/50 right out of the box.
I've had some where I cleaned what look like metal filings out of the jets, ran fine after that.
Make sure your gasoline is free of water too. Pour some into a glass jar, let it sit, make sure there is no phase separation.

Sticking float needle.

Yep, very likely. Especially if it's a new CCP carb

He ordered an aftermarket one for it. Name of the game was quick. And he’s spent a ton throwing parts at it and in fairness it needed some of them. But fuel lines coming from the tank was clogged and everything from there to the carb has been replaced now. New fuel line is 1/4” so that should be right.

I’m regretting taking on this project because it was supposed to be an hour or two and fixed. But he’s also fixing it for his son to be able to use and cut lawns all summer so it’s going to a good purpose.

If the line can get clogged, there could be more trash in the tank, that has clogged up the new carburetor...
Also, the fuel pump (assuming not electric) has 3 lines on it, correct? Make sure the Impulse vacuum line is attached to the engine so it can receive an air pulse.and make sure no fluffy critter has chewed into it.

1. Stuck needle/float
2. Try running with gas cap off
3. Sucking a lot of air somewhere in the fuel line/gasket

Does it have a wire going into bottom of carburetor? If so, the carb has a 12 volt shut off valve that will not allow fuel into carb bowl if not enegized or stuck closed. After you had it running manually feeding fuel, drop carb bowl, if dry, that valve is closed. Check for obstuction, stuck or no 12 volts.

I've had the gasket problem when I replaced the carb on a chainsaw. Put the old gasket back on and worked fine.

You said it won't run unless you are feeding it fuel. How are you feeding it fuel? I had a similar issue on a chainsaw once. If I was spraying fuel into the carb, it would run. Otherwise, no. Turned out to be a crack in the intake manifold that was allowing air into the fuel mixture. It only ran when I was feeding it more fuel. It's possible that you may have air entering the system south of the carb.

Two-cycles are more sensitive to a tight seal on the intake side than 4-strokes. Two-cycles won't run at all while 4-strokes will likely just run rough.

I would suggest tracing correct fuel flow starting at the hose from the tank. It could be something as simple as a clogged screen at tank outlet. Seen it happen before, especially with steel tanks. Work your way forward past the fuel filter to ensure fuel is flowing at each point. Given all the parts you've already replaced, I would not be surprised if the problem isn't with the line from the fuel tank.

Good luck.

These types of motors are easy, fire, fuel and compression so figure out which one’s the problem.

Is the fuel pump electric or vacuum operated?
Have you put a gauge on the motor to check compression because if the pumps vacuum operated and the intake valve is tight it won’t pull enough vacuum to work the pump or if the carb gaskets weren’t put on right or different it could be blocking the port running from the carb to the intake that the pump needs to work.
Vacuum pressure on the pump side?

Your overlooking the basics, if the motor has adequate compression and it has fire which it sounds like it does then you need to remove the fuel line from the carb and prime the engine to check if it’s actually pumping fuel to the carb, if so then the issue is in the carb, if not then you’ve found your issue.

Post a pic of the set up and start your brain back to the very beginning. I’ve done it a million times where I get frustrated and simply overlook the obvious and someone else walks over and says here’s the problem. It happens but this is an easy fix once you narrow down the problem to its root source.

Just went through this same kind of "tune up". 2008 Toro / Kohler Courage 19.

Carb needed replacing, replaced that along with fuel pump, new lines, fuel filter, air filters.

After getting enough battery charge to "crank' it to pull fuel - it ran and I mowed for an hour but it started loosing fire...........hose inside tank came off (broke off).

Fixed that and worked well.

Replaced battery this week only to discover the starter is bad, waiting on Amazon now.............

If you want to check for a intake leak, get your starting fluid/brake parts cleaner and spray it around the intake manifold, at the carburetor mount, and where the manifold is fastened to the head while cranking...
I'd prefer brake parts cleaner since it's not quite as volatile as starting fluid....

Have you tried cranking it over with the gas line off the carb to verify flow to that point?
It might help to let us know what engine we’re working on.

Does it have one of those electric do dads on the bottom of the carb? Think it’s some kind of fuel shut off. Would check that if equipped.

I do hope the OP will get around to telling us what worked to fix the mower. We need to know…because…well, just because…

Check the vacuum line to the fuel pump. this is what makes it function. One little crack will create issues…..regardless of more new parts.

I’ll get around to messing with it tomorrow. Can’t be to many things that could be wrong at this point but I’m sure I’ll figure it. I’m not 100% certain it wasn’t sitting outside for a good part of the last couple years and if that ends up being the case, I’ll bet anything rubber is probably not in to good of shape.