2072 Throttle problems
 

My 2072 was running fine for the first few mowings of this season but yesterday, as I was finishing it started losing power and finally stalled. I thought it was out of gas so filled the tank (it wasn't quite empty) after that it wouldn't run unless the choke was closed. Engine was hot as I had just finished mowing. I haven't had an opportunity to do much more troubleshooting as it was getting dark but thought I'd see if anyone had any thoughts. As far as I know, it's the original carb (at least I haven't rebuilt it since I bought it about 4 years ago and I doubt the previous owner did) I may order a rebuild kit for the carb anyway but adjusting it didn't seem to have any affect on how it ran (at least with the choke closed as it wouldn't run any other way).

MY SUGGESTION..............before you buy any parts.

Check the Fuel Flow from the tank to the Carb. Starting at the tank, the shut off valve has a screen on it. There maybe a "inline" fuel filter. Check for both and make sure they are clean.

Next is the Fuel Pump itself. After making sure there is good flow to the Fuel Pump (see above), check to see if there is good "fuel output" to the carb by checking the connection at the Carb "inlet" connection.

Report back on your findings.

X2 on checking the fuel flow.

Finally had a moment to dig into this. Best I can tell, there is good flow as far as the pump (I can see it pulsing in the filter). It still won't run at all without the carb fully closed. I pulled the carb apart and couldn't see any blockages, I sprayed it down with carb cleaner for good measure. I pulled the plugs and they were DIRTY! I cleaned them up pretty well but still nothing. It was quite high on oil which I have corrected, before I start rebuilding the carb and pull the heads off to clean the combustion chamber, anyone have any other ideas? Could the fuel pump be weak or something? Thanks!

If it's overfull on oil, the fuel pump is leaking into the crankcase. Looking through a filter to see movement is not how you check fuel flow. Sounds like you need a fuel pump. The carb is either dry (not getting gas) or the main jet is plugged. Get that oil out of it, clean things up, replace the pump and report back. The plugs are likely dirty because the thin oil was sliding past the rings.

The over full oil was because I misread the dip stick and over filled it. Oops. What is the best way to check fuel flow to the carb?

Unhook the fuel line, put it into a cup and crank the motor. See how much comes out. I will ad, it would be best to disable the ignition so it doesn't start while testing.

How much should come out? A few tablespoons or am I just looking for more than a trickle?

It's a quarter inch line, it should pretty much pulse out. I don't know if there is a spec, but it should "pump". If it just trickles, it's not enough. Also, it should make a little pressure. Put your finger over it and see if it does. Be careful not to spray yourself in the face, or get fuel all over the place. Should be about 3 or 4 PSI I think.

Great thanks! I will investigate that.