Outdoor Power Equipment (Lawn Mowers, Snow Blowers, Chain Saws and more) Discussions

OK, here's a challenge for y'all. 

My 3-YO Snapper 31" RER ran just fine through the summer.  Now during leaf cleanup, it's been towing the leaf wagon around for 4 weeks, no problems.

Yesterday, I fired up the mower deck, rotating just fine, no encumberances.  I put it in gear, foot off the brake, engine just starts to labor, backfire, and jerk forward, stall if I let it go.  Foot on the brake, deck engaged, clears right up, engine runs normal.  Also, with no deck running, can drive around the yard (flat) with an occassional backfire.    If I let this go, it stalls out, but will re-start right away.

I started with the easy stuff. One at a time, I did the following:

1. Thought I might have gummed up things pouring the last of the gas into the tank (fairly fress <1.5 months old) gas.  - Carb spray into the carb and linkage.  No change

2. Changed inline fuel filter - no change. 

3. Changed spark plug - no change (plug looked ok other than usual burn)

4. lubricated brake pedal linkages all the way through. - no change.

5. Checked oil - good shape.

6. Checked electrical connections, all snug.

No other lifestyle changes for this mower.  No damage, accidents or parties. Gets fairly light use - 1.5 hrs/week summer, winter vacation.

I would really like to finish up the lawn, with a good final mulching, but things ain't looking too good here.  Would appreciate your suggestions.

Thanks!

Bill

Sounds like the culprit is a defective safety interlock switch - just a guess...

Marty

sounds like its starving for fuel under load. as you stated, check fuel flow out of the tank, if theres a plugged screen over it, you may be able to remove the screen from the bottom of the tank....or push it loose from the outside, but that will allow any crud left in the tank to flow through the fuel line, so be sure you install a good inline filter.  its possible too, theres a little crud in the carb. main jet may be partially plugged, or float sticking partially open thus restricting fuel flow. while your at it, check/clean/replace air filter too

Thanks folks.  I've pretty much elliminated the fuel supply, line, filter and carb.   I've also elliminated the notion of being under load, which is what I thought too.

  Did all you suggested including checking the safety switch operation, but that got me thinking:

Here's why I think it's a safety circuit problem - 1. Engine in gear, moves fine.  2. Engine out of gear, off brake pedal, OK.  3. cutting blade engaged and spinning, OK.  4. Cutting blade engaged, in neutral foot off the brake - STALLS.

I'm beginning to think it's the circuit board that seems to control the safety circuitry.  all the kill switches feed into it.  One dealer said he's seen this before.  I may spend the $25-ish to swap out the circuit board. 

Snapper seems pretty proprietary with their wiring diagrams and pretty jealous of their dealerships. 

Bill