Honda HS 621 snowblower - running issue

[TimH100356]

I have not used or started my old single stage honda snowblower in a few years. I was tunning up my lawn mowers and decided to do the same to the snowblower since all the tools were out. Cleaned out the fuel tank (it was dry as well as the carb float bowl)with Gumout Carb cleaner. Everything was pretty clean. Main jet was not clogged, ran wire through it and sprayed carb cleaner through it.
Started mower with choke, fired right up, turned off choke, let it run for 8 minutes and then it suddenly died with no warning...no sputter...just dead. There was some residual Gumout carb cleaner in the fuel tank when i cleaned it and I added a few quarts of fresh gasoline to that. During that 8 min run time, it was never smooth, it doesn't surge but it's close to that without wide ossilation of revs. My memory tells me this is somewhat normal for this machine since I have owned it. Runs pretty smooth, then some roughness then quick recovery and smooth and roughness....continous cycle. I wanted to see if I let it run for a long time if it would slmooth out. See pic of spark plug, looks bad, what is the diagnosis based on the pic and symptoms described. Also, would not restart when I put the plug back in after wiping it off. Any help is appreciated. Thanks Tim

 

[TimH100356]

I was hoping to post a pic of the spark plug but I don't see that option offered to upload a photo. I am a brand new member so maybe I don't get those rights immediately??
The plug was black, everywhere, the tip and the inner cone, all of it black. It was not saturated, I could not really tell at first if it was wet but I think there was some wetness to it. The NGK plug is the correct plug for this machine. I cleaned it but could not get any of the black off, put it back in, it would not fire at all. Finally, pulled out the choke on this warm motor and it started immediately and then died immediately. Ran for about 2 seconds.

Tried pasting copy of photo in body of message did not work, same with a print screen, no go.
Can I send my photo to someone for them to post it?

 

[john_pifer]

Join Photobucket. That site will allow you to link photos here. Use the "IMG" code

 

[Warstud]

Your topic is a bit confusing..says (snowblower running issue) yet you mention your lawnmower dying. Anyway...sounds like you loosened some dirt by cleaning the tank. Clean out the fuel line and carb bowl. Fill the tank with gas and add some Sea Foam or Techron and try starting.

 

[TimH100356]

Sorry for the confusion Warstud. It is the snow blower I am having the issue with. I cleaned the fuel tank, then ran some clean gas through it, then replaced the fuel line and installed an in-line fuel filter since I was not able to "scrub" the inside of the tank, just sloshing around with the carb cleaner. When the "Blower", not Mower, died after running 8 minutes, I checked the bowl and it was full of gas so it is not starving for gas. The black plug also indicates poor burning of the fuel. I wish I would have looked at the plug prior to starting the motor for the 8 min run...however, since cleaning of the plug never removed any of the "blackness", the motor has been running rich for a long time as this blackness is not just on the surface. When a spark plug fails, is it instantaneous or does it show running signs of its immenent doom?

 

[TimH100356]

I just joined photobucket. I copied the IMG link and pasted it above. Hopefully you can see the picture of the spark plug by following this link.

thanks again in advance for any advice out there on what is causing my issue.

 

[bvance554]

I would start by replacing the carburetor diaphragm. May not be the cause of it quitting, but would probably cure the rough running that you say you've always experienced. Its cheap and easy and who knows, it may fix it.

 

[yeehaw1960]

Don't think there is a diaphragm. Remove the screw that screws into the top of the carb and make sure that passage is clean.

 

[TimH100356]

I pulled the carb, the canopy or roof of the float bowl area was caked with cyrstalized [censored]. I did not notice this when I did my initial cleaning of the carb with it still installed. cleaned this out and there was some "stuff" in the float bowl and strainer bowl. Unscrewed the main jet and cleaned again. Got the main nozzle out this time and cleaned all the holes with wire and gumout carb cleaner. Adjusted the valves, both were tight. Put in new gas, changed oil, new plug and some seafoam in the fuel (did not measure seafoam). Motor fired up, actually sprang...leaped to life before half way through the pull on the starter cord and then proceeded to run like it always has...not smooth. Not sure what else I can do at this point other than get the seafoam out of the system and try a new plug again to see if it fouls without the seafoam. After running for 9 minutes, I shut it down and checked plug. Really strange, half of it looked good, the other half looked fouled. Does this half good, half bad plug mean anything to you guys?

 

[yeehaw1960]

Did you remove the screw that screws into the top of the carb? You might not have a screw if it's an older carb. If there is a plastic plug going into the top, remove the plastic screw that sets the minimum RPM. Pry the plug out and ensure the passage in the tip (very, very small passage that I use a miniature drill bit to clear) is clear. This can make a world of difference.

 

[TimH100356]

thanks for the tip yeehaw. I was told not to mess with that one screw due to the plastic cover being very difficult to remove without breaking it. Have you removed this cap and screw before? Is there a technique or suggested tool to use to get it out? I've been in this thing a few times now in the past week so it's no big deal to me to undress her again and remove and clean that part if you think it can be done without breaking it.

While I had it runing today, I lay down on the driveway and looked up into the motor area, from the back of the blower and I could see the Governor Rod moving back and forth (in and out) and the surging follwed this movement directly. There is no throttle on this machine so I cannot manually perform what I was witnessing. With a needle nose plier, I grabed the Governor Rod and held it in place and the surging stopped, it ran smooth but as soon as I released it, it went back to the surging pattern with the corresponding movement of the Governor rod. What is the control mechanism in the motor that is communicating and then actuating the movement of the Governor Arm and it's Rod to the carb? I took a video with my phone and emailed it to my email account to save and then upload into Photobucket but it's been 8 hours and the video still has not arrived yet, phone says "sending". It's probably to big for my email account. does anyone know if I can send the video directly to Photobucket?

The only other time it ran completely smooth was for a period of about 45 seconds, while it was running out of gas in the fuel tank. Usually, with most small motors I have experienced, as the motor is running out of gas, it starts to sputter and run rough before quitting. This one is just the opposite, it smooths out and runs great and then suddenly stops with no warning. This smooth running when starving for gas and the black spark plug tell me this motor is running rich...or not getting adequate air supply. Does that screw on top of the carb with the plastic cap control fuel flow or air flow? Could it be causing the motor to run rich? Is the position of the screw adjustable or is it something you turn in until it bottoms out?
Thanks in advance for any comments. Tim

 

[TimH100356]

video with audio of surging

 

[TimH100356]

 

[TimH100356]

click the picture above to see the video of the governer arm moving on it's own, creating the surging sound

 

[yeehaw1960]

Assuming you have the non metal screw type, turn the screw in that keeps the idle from falling below a certain level. Count the number of turns it takes to bottom out. Remember that number and remove the screw completely. The "plastic plug" that is exposed is pressed into place. Gently pry it up with a flat head screw driver. After it's out, you need to ensure the tiny (TINY) passage that goes through the tip and comes out where the larger holes are on either side is clear. I have to use the smallest bit in my miniature drill bit set to do this. Once that's clear, (with bowl removed) blow air down in the hole in the carb where the plug came out. A little carb cleaner down that hole couldn't hurt. Reassemble it the way it came out, but pushing it in and tapping on it until it bottoms out. It will only go in two ways, both of which are correct. The flat spots on either side of the head are your guide to reinserting it correctly. Reassemble and hopefully it will help. Honda and dealers make a lot of money from people who don't know about this "other" spot.