Snowblower issues - RC-Monster Forums

BrianG · 12:24 AM

OK, it's supposed to snow a decent amount tomorrow and my snowblower is acting stupid. First a little background:

It's a Simplicity snowblower with an 8HP Tecumseh engine. It was running fine last year until it just died on me. After inspecting it, I found gas leaking from a hole. Something must have worked loose and fell out, so I plugged it with a 4mm screw from my r/c box and it seemed to run fine after that for the rest of the year (about 3-4 more uses).

So, this year, I decided to fire it up and it's running like crap. Actually, it runs nice, once I can get it going, but keeping it going is a challenge (and getting it started back up).

In previous years, to start it, I followed this procedure:
When the engine is cold, I start with the choke on full, throttle about 1/2, and then use the electric start. After a couple cycles, it turns on. I let it warm up a little, then set the choke about 1/2 way and bring the throttle up to running speed (just about max). After the motor warms up a while, I turn the choke off completely. Then I'm able to do whatever I need to do. Shutting it off was just a matter of lowering the throttle and hitting the on/off switch.

This year, the cycle is a bit different:
When the engine is cold, I have to set the choke to "off", throttle almost "min", and then crank it. Setting the choke or throttle to any other position won't let it start at all (won't even "catch"). Even then, it has a hard time trying to start; it seems like it "fires" only about 25% of the time resulting in a very rough idle and more than normal smoke coming from the exhaust. Eventually, it gets to a point where it fires about 50% the time, then 75%, then will idle somewhat decently and I can increase the throttle to running speed. But since the choke is already on full "off", it starts to get rougher as the engine warms up. I can get one pass of the driveway done before it starts backfiring, running rough, then it stalls, and then I have a heck of a time getting it working again. It's faster for me just to shovel the stupid driveway. Also, when I can get it running ok, shutting it off is odd too. I lower the throttle, flick the on/off switch and it continues to run for about 20 seconds.

Nothing happened between last year and this year, so I don't know what's up. Fuel delivery seems good because I've gone through a tank and a half between trying to start it and accomplishing what I can with the driveway. The only oddity is that screw hack job I did last year, but it ran fine several times after that, so I don't know what's up. I don't even know what that area does. So, I included a couple of pics. The first one just shows the muffler, choke, throttle, and on/off switch. The second pic (sorry about the blur), is the area underneath the muffler and shows where I put that screw in.

Can anyone give me a hint of what could be going on? The small engine shop said to bring it in, but there's no way I'll be able to fit it in my little hatchback. And I don't know of anyone who does house calls...

I'd really like to know what that screw is supposed to be and if that's the cause of my problems...

Arct1k · 12.23.2010, 12:31 AM

Did you use fresh gas mix?

Your ratios may be off.

BrianG · 12.23.2010, 12:34 AM

Sorry, it's a 4 stroke, so no mixing. Straight gas ever since I got it about 6 years ago.

DrKnow65 · 12.23.2010, 12:35 AM

In your picture it looks like I'm seeing the bottom of the carb? If that is the case then the part that fell out is likely the mixture screw. It would have been a fine thread with a tapered point and a spring which keeps it's position once set. From your description you are running the motor very rich. You could try backing the screw out a bit and see if it gets better (or likley worse). If you are very handy with a dremel and a drill you could fabricate the taper on the end of the screw and use a nut to lock in the position. You'd want about a 20 degree taper and the setting would be roughly 1-1/4 turns from fully seated.

BrianG · 12.23.2010, 12:41 AM

OK, that helps. It had 4mm threads so I had several screws laying around. The think is, I have no idea how long it should be. Now that I know what the part is probably called, I did a google search and found this:

That's MUCH longer than the screw I have in there. Although, I'm not even sure that's the length I need, so I'll just look for the longest one I have, add the taper, and then screw it in slowly and hope it's long enough.

DrKnow65 · 12.23.2010, 12:47 AM

Yah, the business end is the taper. It goes into what is basically a pressed in flat washer so the taper is not hyper critical, as long as it will partially plug the hole and give you some adjustment. The hole is propably not threaded the whole way to the taper since there is likey an o-ring or felt ring in there to seal before the threads. But now you can see what you're going for.

I'm glad I finally got a chance to help YOU in some small way

you add so much to the forums here

What's_nitro? · 12:57 AM

Buy 2 Mamba XL systems and convert it to BL power. Done!

DrKnow65 might be right. If the mixture screw fell out and the screw you put in isn't long enough it will make the engine run rich. That could explain why you're using so much fuel with it barely working properly...

edit-

It took me too long to read the thread and post...........

lincpimp · 12.23.2010, 01:03 AM

Depending on the carb model that may be the fuel float bowl drain screw. Your pics and description are crap, BTW, a better pic would be nice!!!!

If it is the mixture screw then what drknow said is true. I would replace the plug anyways, and when you do check the spark condition by attaching the plug wire to the plg then grounding the threaded portion of the plug on the enfgine case. Turn it over and see if it has a decent spark. Most small engines use a generator to create spark and a fowled plug will cuase no end to running issues. Even cleaning the plug is a waste, buy a few new ones and keep them handy.

Do you drain the fuel out of this during the summer? You may have a stuck fuel float that is causing the carb to not shut off the fuel flow to the carb which can also cause a rich condition. A carb rebuild kit may not be a bad idea.

lincpimp · 12.23.2010, 01:05 AM

Say you love me later:

http://forum.doityourself.com/outdoo...mseh-carb.html

(not a link to Rick Ashtley's smash hit BTW)

lincpimp · 12.23.2010, 01:08 AM

And this looks like the right kit:

http://compare.ebay.com/like/3901166...=263602_304662

You may be able to just pick it up at the local small engine shop and install it yourself...

BrianG · 12.23.2010, 01:24 AM

@What's_nitro: That's a project for a different day...

@linc: Thanks for that info, but it might as well be greek. Electronics=easy. Engine repair=lots of swearing and end up losing lots of money (the price of the attempted repair, and the time/labor charges to un-do the mess I did and then do it right).

I don't drain it per se, but I do run it until the engine dies at the end of winter. I plan on getting a new spark plug on the way home tomorrow, but I did test the spark and it looks good.

Below are a couple more pictures, one a less blurry image of the needle area, the other my home made needle valve I made.

DrKnow65 · 12.23.2010, 01:44 AM

The bowl drain is the brass screw to the left of your missing bolt. The big brass fitting your screw goes in also holds the bowl in place. If you remove the fitting the bowl will come right off and inside would hang the float which levers against the needle that stops the flow of fuel into the bowl (very similar to the float in the toilet bolw). With the fitting out the far end should have the oriface (hole) your needle partially plugs up. If you felt ambitious you could you could bench it and make sure your needle is the correct length.
Your needle looks good but you may want to give it a bit more of a taper, the adjustment will be tough as it will change rapidly with that steep of an angle. Good shade tree work :-)

lincpimp · 12.23.2010, 01:54 AM

Ahh, much better pic!! Yes, the center is the needle valve, and the side is the drain. Your bolt needs to be alot pointyer, as DRNO pointed out.

Mechanical stuff is pretty easy, alot easier at this level than electronics!!! Small engines can be a pain, but they are just extra sensitive to dirt and crud, especially the carbs.

The new plug will help, just make sure you do not soot it up by running it too rich. Plug should be light tan when the engine is warm and running well. Much darker and you need to lean the mixture some. Turn the screw in more...

Reading plugs is the old timer way to do it... But it still works... You are reminding me to do the maintainance on my generator...

_paralyzed_ · 12.23.2010, 03:43 PM

the fact she starts with no choke leads me to think the air filter is clogged. (as if it is already choked)

did a mouse make a nest in your airbox over the summer and clog your intake?

fresh gas, a fresh plug and a clean air filter are critical for small engines.

BrianG · 12.23.2010, 04:02 PM

I kinda thought that too (I do know a little about it's supposed to work), but after looking around, I found there is no air filter. I thought it odd, but didn't see anyplace where it would go if it was supposed to have one. I got this used/rebuilt from a place that sells snowblowers, lawnmowers, etc, and they had just rebuilt the engine. So, I would hope they wouldn't leave it off if it's supposed to have one.