B & S 13.5 MTD mower

11 years ago

I have a MTD 2006-2007 riding mower with B&S 13.5 intek OHV single cly motor. It probably only has 100 hours on it.

My wife was using mower last fall when mower deck wouldn't engage. The deck engagement cable sping was broken and another spring attached to deck was broken. She said she didn't think she hit anything.

Mower sat for 2 months before I replaced parts and tried to start. No success so I tried to prime into carb and only mild popping during cranking. I then pulled plug and checked spark, it looked weak (since then, two mower shops and briggs website have informed me no such thing as weak if you have spark!). I pulled shroud and mouse had mad nest while mower sat and chewed halfway through sparkplug lead near ignition coil.

So this spring I replace ignition coil and get nice fat blue spark when cranking, but can't get engine to start despite priming into carb and directly into cylinder through spark plug hole, gas or starting fluid.

I then pull flywheel bolt and see crankshaft key in place, no shearing. Seems like compression is OK, but I adjust valves anyway, .004 Intake/ 006 Exhaust, using B&S technique and old style, with intake fully open vice versa, still no starting even when priming carb or through spark plug hole.

This engine has low hours, never smoked like it would from worn rings, but I don't know what else could be wrong?

When I watch the valves there seems to plenty of lift, does anyone know what the cylinder pressure should be using a compression gauge, using the electric start?

Sort by:Oldest

Comments (8)

rustyj14
11 years ago
I don't know that, but check the ignition coil ground wire, that thin wire that grounds out the coil. A mouse might have chewed the insulation off it, too, and that wire might be shorting out the coil, which would cause the condition you describe. Check wires at key start area, behind dash panel, aldo check all safety switches, the ones that keep the engine from starting, if not on seat, and clutch pedal pushed in all the way down. Check for disconnected wiring to mower deck, if so used.
Sounds like the "Safety Gremlins" have struck again! LOL: RJ PS: Do you know that the safety plug under the seat must be attached and working? Those diabolical safety engineers are sneaky!
doccod
Original Author
11 years ago
Update:

All safety interlocks and coil grounding are disabled. Coil is installed properly (not upsidedown. Compression is 55 psi leaking down to 50 after ten minutes, 40 after 18 hours. Local shop says this is OK. The only thing I have NOT done is remove carb and prime directly through intake port! any ideas? Priming through spark plug hole is iffy, since it horizontal and hard to get to. I get very good spark when cranking with plug out, nice fat blue spark.
Related Professionals
Brookside Landscape Contractors · Berkeley Heights Landscape Contractors · Bound Brook Landscape Contractors · Deerfield Landscape Contractors · Holtsville Landscape Contractors · Palatine Landscape Contractors · Riverhead Landscape Contractors · Vermilion Landscape Contractors · East Renton Highlands Window Contractors · Framingham Window Contractors · Mill Valley Window Contractors · Mokena Window Contractors · Morro Bay Window Contractors · Suitland Window Contractors · University Window Contractors
rcbe
11 years ago
use rattlecan carb cleaner. re-hook up all safety switches. sit on seat with PTO sw off, clutch/brake pedal fully depressed. No choke, half throttle.
Have assistant spray a cuppla shots directly down carb throat. quickly crank engine. If engine pops and tries to start, there is a fuel delivery prob.
If no start attempt by engine, ignition problem. Since you say you now have good spark, pull flywheel completely off and closely re-check square key for being sheared/cracked.
replace as needed.

lastly - if start prob is solved - forbid wife to operate mower - she and mower will love you for it.
doccod
Original Author
11 years ago
rcbe: Hmm, OK I didn't pull flywheel off completely since I could see key square in keyway, just pulled bolt. So key can be "cracked" enough and still change timing enough to disable motor from starting? I have brand new flywheel key in package.

PS, I agree with last comment, she still swears she didn't hit anything, I can tell from the gouges in the blades and deck damage she didn't!
rcbe
11 years ago
if "somebody" hit "something" hard enuff with engine and deck running full blast, shock transmitted back thru crank can indeed damage key....
rcbe
11 years ago
forgot - if cracked/damaged, do replace with OEM part. no aftermarket.
doccod
Original Author
11 years ago
rcbe: Hmm, OK I didn't pull flywheel off completely since I could see key square in keyway, just pulled bolt. So key can be "cracked" enough and still change timing enough to disable motor from starting? I have brand new flywheel key in package.

PS, I agree with last comment, she still swears she didn't hit anything, I can tell from the gouges in the blades and deck damage she didn't!
doccod
Original Author
11 years ago
I have B&S key, will replace this weekend thanks