Two issues - engine idle and self propel

15 years ago

Hi all - I've finally gotten around to messing with my push mower and I've got it sort of working, but still not 100%. It's a 6 year old Craftsman real wheel drive walk behind. There's still two big issues:

1) The mower has the Honda GCV160 5.5HP motor on it. It runs great at full speed, but when you cut it back to idle, the motor surges and doesn't run well at all. Sometimes it sputters out and dies, but normally it just surges. I thought the problem was the carb, so I dismantled it, cleaned and soaked the jet, and reassembled it. It didn't make much difference. I noticed the gaskets are in rough shape, so I'll order new ones and see if that helps. Might have a vacuum issue with the gaskets as bad as they are! Would that explain this?

2) At any speed, the self-propel is always engaged just a little. When I stop to dump the bag, unless I kill the motor, the mower wants to wander off across the yard. I haven't taken it apart to see if I could fix it... Just came here for help. There's an adjustment button on the back of the self propel handle, but that didn't seem to help anything.

Thanks for the advice!

-Jeff

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Comments (15)

bill_kapaun
15 years ago
A vacuum leak could easily cause your surging symptoms.

Without you providing the Sears 917.xxxxxx number, only a psychic can determine what drive system your mower has.
There may be adjustment instructions in your owners manual?
jfoust
Original Author
15 years ago
Oh yeah, forgot to put the model # - 917.377790. The only thing mentioned in the manual is what to do if the self propel gets too slow, and that's the adjustment button on the bottom of the lever, which I had already tried.

I'm going to order all new gaskets and see if that clears up the sugring problem, but was hoping to nail down the problem with the self propel in case I need to order something for that too!

Thanks!
Jeff
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bill_kapaun
15 years ago
To tighten drive cable-

"2. Pull drive control lever ALL THE WAY BACK to the handle.
3. Push button on underside of drive control. While holding button in, return drive control lever to disengaged
position ALL THE WAY FORWARD.

How pushing the button, pulling the handle part way back and then releasing the button? (or some combination of reversing the tightening procedure?)
redsky42
15 years ago
You really shouldn't be taking the bag off with the mower running anyway - serious safety issue. Anyway, what's the big deal with pulling the cord again after dumping the clippings? I think the surging issue has been covered, I agree in thinking it's a vacuum leak. Also, the drive mechanism wanting to stay engaged also sounds to me like an adjustment problem.
jfoust
Original Author
15 years ago
Hey redsky - the mower has a blade brake on it so you can dump the bag (or self-propel without cutting) without having to kill and re-fire the motor every time.

Thanks for the reply, Bill. I tried fiddling with the adjustment button in various states of pressing the lever and it didn't seem to help... Just affected the top speed, but never got it to stop. I'll take the cover off the back end and have a look at the belts and pulleys that control it. Maybe something to discover there!

The other thing I failed to mention is that I replaced the rear wheels. Prior to that, the wandering problem didn't exist, but I don't see how bolting on new wheels would cause the wandering. The teeth were completely gone on the right wheel and the left one had a few chipped off, so I replaced them both while I was at it.

Thanks again for the advice guys and I'm always open to more suggestions!

-Jeff
tomplum
15 years ago
ARe the wheels running straight? The arms can sometimes bend, causing the drive to eat plastic teeth.
If the belt is in place and the pulleys clean, try the adjustment procedure whilst holding back on the the cable end by the trans. It would be a good thing to verify that the cable isn't starting to fray/ bind at the same time.
jfoust
Original Author
15 years ago
Follow up - I opened up the cover on the deck and there was a pound of funky dirt and clippings in there, so first I cleaned that all up, then I dismantled the pulleys and lubed them up, reassembled everything. The belt is starting to show its age, so it probably needs to be replaced soon. I also noticed that the handle doesn't seem to fully release when you let go, so the pulleys don't go all the way slack, keeping the drive slightly engaged. I need to dismantle the handle and see what it looks like in there, just didn't have time to mess with it tonight!
redsky42
15 years ago
Hiya jfoust. Well that's interesting. Guess I'm a bit behind in the times. It sounds safe enough if the blade is stopped. It sounds like you found your problem with the drive unit, let us know how it turns out.
jfoust
Original Author
15 years ago
Next update... I replaced all the gaskets from the air filter all the way into the block. Also cleaned the carb a third time while I had it all apart. Replaced the throttle return and governor springs too. I put on a new plug earlier in troubleshooting, and the only thing that I haven't done is replaced the air filter, but I've run the mower with the filter off completely and it still surges!!!

I did find that if I manually play with the choke, I can get it to stop surging, so it sounds like it's just running lean at everything but WOT. I'm about out of options and I'm ready to just live with it, since it still works at WOT and that's where it is when I mow the lawn!

The self propel thing is fine as long as I remember to push the lever all the way forward and don't just rely on the spring to completely bring it back! Still haven't found the time to take that lever apart and see what's wrong.
cuejal
15 years ago
Jeff,

I have a 5-year old Craftsman with the Honda GCV160. It's designed to run at only one engine RPM. The "throttle" control is really only a choke control, i.e., you can't make it idle normally.

Mine is not self-propelled so I can't offer any opinion on that.

Hope that helps.

Jim
jfoust
Original Author
15 years ago
Thanks Jim... Mine used to run great at a low throttle setting, so I know it will.

In fact, it was so quiet at idle that when it was running right and the wife came out to yell at me about something I could cut it back to low and have a normal conversation while standing right next to it. Nobody had to raise their voice and you could hear every word just fine. No surging and running like crap either!

I never have checked the fuel cap vent, so that could be an issue. I'm going to look into that tonight. If that fails and nobody has any other suggestions, I'm just going to give up for the season as long as it runs okay at WOT. Maybe next season when I de-winterize it, I'll take it somewhere and get it tuned up and looked over.
bill_kapaun
15 years ago
Just ran into a low speed surging issue on my 21 year old Honda.
It started to surge upon start up pretty bad and worse the slower the engine speed. After mowing for awhile, it disappeared and would idle down fine.
Turns out the throttle shaft on the carb was gummed up a bit.
The throttle couldn't track the governor very well. It would stick and then when it did finally move, it would "jump" too far.
jfoust
Original Author
15 years ago
Hi Bill,

Do you mean the shaft that holds the butterfly? If so, I checked that and it's moving freely. All of the linkages, rods, and arms that connect to the throttle move freely and seem to not be bent or anything like that. I've tried just about everything I can think of at this point, but still no luck!
cuejal
15 years ago
I said:

"I have a 5-year old Craftsman with the Honda GCV160. It's designed to run at only one engine RPM..."

Jeff responded:

"Mine used to run great at a low throttle setting, so I know it will."

Sorry Jeff, I was being parochial as my version of the mower is set up to only run at one RPM.

Another person had the same idle issue below, which was resolved by cleaning the carb, specifically the idle passage I guess:

http://www.gardenbanter.co.uk/showthread.php?t=109209

Maybe you just didn't get it clean enough?

I'm not a small engine mechanic by any means, but occasionally work on friend's mowers. If I remember correctly, soap bubbles have helped locate the source of vacuum leaks around the carb, for instance. I know I've had to rework the mating surfaces (float bowl I think) to get a gasket to seal properly.

Just some thoughts.

Jim
rolm
15 years ago
For the reasons mentioned I do not like Honda engines I will take a B&S quantium engine any day of the week. Honda way over-rated

Two issues - engine idle and self propel

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