Small engine carb trouble

I have a riding lawn mover ( a yard pro with a 17 hp ohv170 tecumseh engine).

My problem is this: It takes ten sec of cranking to get it to start, and then it needs to be on 3/4 choke to stay running, and has no power when it does run.

We tried removing the carb, cleaning every port, checked every seal on the carb, and did all the basics (even made sure it had good gas!) Any ideas? Thanks.

The problem is still in the carb, I suspect. I’d get it running at full throttle however it requires and cover the carb with a rag to choke it off til it dies. Do this 3 or 4 times and you’ll most likely suck out whatever is stopping the fuel from flowing properly from the venturi ports.

The greater percent of ethenol the government wants our cars to burn makes it rough going on most small engines.
I heard a piece on this just today.
I wonder if the fuel you purchased had 10% ethenol or similar ?

Does this engine have adjustable valves?? Did you disassemble the carb to clean it? Is it a “pumper” carb with rubber diaphragms or a float chamber carb with a main-jet…

No pumper, it does have a float chamber. We pulled it apart sprayed everything down with carb cleaner, so there should be no crap in there. It only has a fuel adjustment for the tube that pumps the gas into the mixing chamber.

Well its starved for gas as indicated by having to have the choke on. Change to non-ozygenated gas and put some Stabil in it for starters. Then I really think you should just get a carb kit for the $10-15, and change out the jets and so on. Also make sure the float is not leaking. I had this with my twin Briggs in the summer and went through two fuel pump diaphrams and a carb kit. The parts are so cheap though, you just can’t get everything cleaned out properly and easier to just replace. Also check the fuel filter and any strainer in the tank etc. that may be clogged, as well as making sure the vent hole in the gas cap is ok so the tank can breath.

I have found that cleaning out the small passages in the carburetor can be done with a single strand of a steel brush.

Two things I forgot to mention. 1) it runs if I put the throttle all the way down to the lowest setting, it will sit and idle, and will rev up a little, but will start surging and fail when you get into the power band.
2) it backfires out both ends when it is stalling and surging.
I made sure the float was not leaking, and there is plenty of gas coming from the tank.

I just went through a similar situation with my 1990 snowblower. It would start the after a bit sound exactly like starving for gas. It would restart and be ok and after limping through a few snowfalls would not start at all. Starting fluid started off great. Over the summer I had done a complete cleaning and check of the carb. Decided to do it again, but no improvement.

Figured as a last resort to drain the tank and try some new gas. Upon draining the tank I was surprised to see a 1/2" tall x 1/4" brass filter molded into the tank, with all sorts of sediment around the bottom of the tank. No mention of it’s existence anywhere I read in repair manuals etc. I used a turkey baster to suck out the debris as due to the tanks design the sediment could not be rinsed out the top.

Drain your gas tank, maybe you have one too! (based on the assumption you have no visible gas filter or gas pump failing diaphram)

if you are using regular try mid-octane…my craftsman snowblower runs better on mid-octane…sears dealer also suggested it.

The other thing is that should have a fuel pump on it with the diaphrams and so on that should be rebuilt. If you get the carb kit, make sure it includes the fuel pump parts. If you eliminate the carb and fuel supply, you could always have a recessed valve. That though should allow it to run ok except not have any power. I had that with my Tech snow blower but was lucky enough to still be under warranty.