HRX217 won't run. Need help determining what is wrong

I've got an HRX217 (non auto-choke) that is giving me some fits.

I've had it for about 12 years (?) and have always maintained it well.

At the end of last season, every once in a while it would start sputtering, missing, and running terribly for 30 seconds and then start running ok again. I started off this season with it doing that again. It wasn't happening much so I didn't spend any time trying to figure it out. Recently, it got worse, and eventually wouldn't run at all.

I've been working on engines my whole life and I've had my fair share of small carbs apart for a cleaning which fixes 99% of the problems. I figure, no problem, this is an easy one.

As usual, I pulled the carb, disassembled it as much as I could, dropped everything in my ultrasonic cleaner, and then blew it all out with air. Reassembled and reinstalled. Same problem, won't run. Sort of starts, coughs, sputters a little, will barely idle. Sounds strange though as if the throttle plate is open, which I verify is, even when not running.

Naively assuming I didn't get a small passage clean, I just order up a new carb and gaskets from Honda. I'm not wasting time with this.

Put it on tonight, and same crap! Won't run, pops, backfires, sort of idles very slow, maybe.....

I verified good gas flow from petcock.
I checked choke operation, that seems perfect. Wide open choke plate anywhere in the slow to fast range, and plate is closed in the choke position.

Is there something in the governor springs that could be causing this? I get the mower hooked on branches and stuff all of the time. I never have had the springs off, but I verified the connection points against many pictures and videos so they are correct. I noticed that the short spring on the bottom of the governor arm has quite a bit of slack in it. As in, there's no preload, and the hook isn't pulling on anything at all with the throttle lever at idle position. The lower spring doesn't look stretched at all, and is attached on both ends. The long, skinny upper governor spring seems ok. It opens the throttle plate if I close it by hand. I'm not sure what else to look for on this one, but everything seems ok.

I noticed again that the throttle plate is wide open when the engine isn't running. It moves very freely with nothing connected, the linkages all move nicely, but why is it open? I don't ever remember the sound of a wide open throttle plate when starting it when it ran well.

Please offer any thoughts or suggestions. This one has me stumped and I don't like that.

Thanks.

Sorry, I just realized i also posted this in small engine and mower repair. Hopefully there are some suggestions in one of the threads or a moderator can delete one or the other.

Have you replaced the sparkplug since the sputtering began?

http://www.lawnmowerforum.com/members/list/r100.html?pp=30&pp=30

send robert@honda a private message regarding mower, include MZAM number, he's the Honda go to guy

To ease your concern about the throttle plate being wide open when the engine R.P.M. is zero, that is normal because all engines equipped with a constant speed governor has the plate wide open when the engine is dead. When starting and you've adjusted the throttle cable to idle, the plate is wide open. Open the throttle cable to full throttle when starting and the throttle plate is wide open. It's just a fact of constant speed governed engines.

TLAR640 said:

Have you replaced the sparkplug since the sputtering began?

Click to expand...

Pulled the spark plug. Looks good. A little carbon on it but not much at all.

I replace the plug each season so it hasn't seen much run time at all.

mckeand13 said:

I've got an HRX217 (non auto-choke) that is giving me some fits.

Click to expand...

Let's start with the full serial number off the back of the mower deck; this will tell me which exact model you have, and I can look up some troubleshooting for you:

robert@honda said:

Let's start with the full serial number off the back of the mower deck; this will tell me which exact model you have, and I can look up some troubleshooting for you:

Click to expand...

Here you go:

HRX217TDA
MAGA-1070088

One more thing I was going to check was gas. I don't think the gas that was in the tank was old or bad, but I wanted to rule it out.

I drained the tank last night (lots of flow the whole time through the petcock) and I filled it up with fresh stuff. It was late so I didn't have time to pull the rope.

mckeand13 said:

Here you go:

HRX217TDA
MAGA-1070088

Click to expand...

So that's a first-gen HRX, with a standard manual choke.

Step 1. Confirm the choke plate is fully opening and closing. Does the engine run/start smoother with the choke closed?
Step 2. Consider replacing the carb (full list price is only $16.23).
Step 3. Triple check the position and orientation of each gasket, spacer, insulator, etc. It is VERY easy to get one on upside down or backwards, and in many cases, the carb won't be able to vent.