Surging Powermore 179cc in MTD - Snowblower Forum : Snow Blower Forums
 
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post #1 of 7 Old 01-11-2015, 12:19 PM Thread Starter
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Surging Powermore 179cc in MTD

My son-in-law gave me his two year old MTD snowblower for use at or cottage. I used it for the first time yesterday and found it surged and popped back badly. I was only able to get it to run with the choke on. He said it never ran without the choke on since new.

I found this forum and learned this is a common problem with Powermore 179cc (and other) engines. I was able to drop the float bowl and clean the main jet and emulsion tube. There was no obvious junk in the jet and only a little sediment in the bottom of the bowl. It did run a little better, but still needs the choke and pops and surges badly with it off.

For the life of me I cannot figure out how to get the engine shrouding off to get at the carb and clean the idle jet. There's one bolt at the bottom front, hidden by the belt shroud, which goes into the crankcase and must be on with 150# of torque. A 10mm open end or box wrench just slips off.

At the back I have tried to pull the throttle and choke knobs off, but they won't budge. I'm afraid to use force, they're just plastic. Is there a secret to getting access to this engine? It's sure not a user friendly design and the so-called manual is worthless.

My plan was to clean the idle jets and try again. If that didn't work, I was going to try drilling the jets a bit.I understand there are no adjustments on the carb.

Thanks, Jim
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post #2 of 7 Old 01-11-2015, 01:17 PM
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If you open the main jet just a little with a micro drill it will cure the surging and save you the aggravation of pulling off all the shrouding. I forget what number micro drill I used on my 212cc the first time but for reference I was barely able to pass one of my wife's sewing needles through the jet.
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post #3 of 7 Old 01-11-2015, 01:47 PM
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Hello and welcome to SBF jjscott. I'm not sure what service manual you have, but this one is pretty detailed and should help with the disassembly and possible repair. I hope this helps, if not, come on back and some of the smarter folks here will be glad to assist.

http://service.mtdproducts.com/Train...horizontal.pdf

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post #4 of 7 Old 01-11-2015, 02:01 PM
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Iyou drain as much fuel as possible, and tilt the machine forward. You can remove the bowel and unscrew the jet . Spray carb cleaner in, into where the jet was screwed in and clean the the jet. Also, as stated above, opening the jet a little helps alot on those motors. The are jetted really lean. If you have a welding torch cleaner set. You can use it file file the opening up. But be cautious, and take a little out at a time.




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post #5 of 7 Old 01-12-2015, 08:26 AM Thread Starter
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Thanks for the welcome and replies. My manual is for starting and running instructions only; the link gives all the details - what I need.

I guess I'll open the main jet a bit instead of trying to get the shrouds off. I'm not at the cottage where the machine is, so it may be a while. But, I will report on results.

Thanks again, Jim
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post #6 of 7 Old 01-18-2015, 10:05 AM Thread Starter
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First attempt was to drop the float bowl and open the main jet with a #68 drill. The engine did run a little faster with the choke on but still surged with the choke off.

Next attempt was to pull the shrouds. Not a user friendly job. The knobs do pull off with enough force., The handle interferes with getting the shroud off because of the long studs that hold the carb on. I decided to cut away the plastic instead of removing the handle.

With the shroud off there is access to the idle speed screw and the idle jet. It was hard to tell if the jet was clogged or dirty. I used a #79 drill to clean it out. The drill wouldn't go in at first, so I twisted it until it went through. It may have opened the idle jet some. The #79 was the smallest I had.

I had read that a too slow idle can cause surging, so I increased the idle speed by 1/4 turn in. I drilled a hole in the shroud so I could get a screwdriver to the idle screw when everything was back together.

Then all back together. It now runs full throttle without the choke on. There's no snow to test how it runs under load, but the problem may be fixed. The solution was: clean the carb, open both jets, increase idle speed.

Thanks to everyone for their help.

Jim
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post #7 of 7 Old 11-07-2018, 10:13 PM
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Quote:
Originally Posted by jjscott View Post
My son-in-law gave me his two year old MTD snowblower for use at or cottage. I used it for the first time yesterday and found it surged and popped back badly. I was only able to get it to run with the choke on. He said it never ran without the choke on since new.

I found this forum and learned this is a common problem with Powermore 179cc (and other) engines. I was able to drop the float bowl and clean the main jet and emulsion tube. There was no obvious junk in the jet and only a little sediment in the bottom of the bowl. It did run a little better, but still needs the choke and pops and surges badly with it off.

For the life of me I cannot figure out how to get the engine shrouding off to get at the carb and clean the idle jet. There's one bolt at the bottom front, hidden by the belt shroud, which goes into the crankcase and must be on with 150# of torque. A 10mm open end or box wrench just slips off.

At the back I have tried to pull the throttle and choke knobs off, but they won't budge. I'm afraid to use force, they're just plastic. Is there a secret to getting access to this engine? It's sure not a user friendly design and the so-called manual is worthless.

My plan was to clean the idle jets and try again. If that didn't work, I was going to try drilling the jets a bit.I understand there are no adjustments on the carb.

Thanks, Jim
I just had the same problem with MTD 179cc Powermore engine on a single stage snowblower and here is what worked for me. Remove carb bowl, check float, needle and seat to make sure float stops fuel flow at correct height. Float set level with carb body is fine. Next remove the main jet and emulsion tube. I use a #79 drill and run it thru all 11 holes in the emulsion tube and spray with carb cleaner and blow out with compressed air. Then take the main jet and drill it out with a #65 (.035") drill bit. This typically works well but I've had situations where I went all the way up to a #60 (.040") drill bit to get the engine to run correctly.
Make sure valve and gaps are set correctly, oil is correct level and fresh gas is used. I use a Champion RN9YC Pplug gapped at ..028". These engines and carbs are not the same quality as the older Tecumseh or B&S and I've found the tolerances on many parts need to be adjusted for the engine to run properly
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