mower kills with clutch release or blade engage

[fish4specs]

Hi, I'm new to the forum but did a quick search and couldn't really find anything similar.

I have a craftsman 42" rider model 27639 with a Briggs 18hp engine. the mower will start but when it is running, it dies when i release the clutch or if i keep clutch engaged and try to engage the blades it dies. I test the interlock switches at the clutch and the blade engage lever and they both tested good. I also tested the seat kill switch and it tested good. I had a new switch and replaced the old ones (in addition to testing with multmeter). when switch "button" was released engine died. Didn't have to actually engage the trans. for engine to die.

Any help would be greatly appreciated and thanks in advance.

 

[fish4specs]

Well went back and retested everything. Unconnected and reconnected all electrical connections. Think it was a blue pigtail loop that was loose or dirty, anyway it started and ran, but alas, then the blade engage cable broke. bummer

 

[motoman]

Well went back and retested everything. Unconnected and reconnected all electrical connections. Think it was a blue pigtail loop that was loose or dirty, anyway it started and ran, but alas, then the blade engage cable broke. bummer

fish4specs, Waiting to hear your update, but sounds like load is killing the engine. You are running on both cylinders?

 

[Eyeball]

I have had this problem twice. The first time it was a battery on it's last leg and it couldn't put out enough current to drive the electric clutch. Changed battery and it fixed it.

Now, today 6 years later, I have the same symtom you described again. This time it's the Electric Clutch is nearly shorted across it's coil. The coil should read approx 2-4 ohms, and mine is readin .2 ohm, which is almost a short. So when you pull the PTO switch to start the blades, the electric clutch essentially shorts out the battery and the whole engine dies.

I am about to install the electric clutch once the part arrives. WHAT I NEED TO KNOW IS how much torque do I put on the mounting bolt, and what size mechanical gap do I need to set in the clutch itself.

 

[damnokrafarmer]

Even though this is old thread, I am answering it for the help of others who end up here...as I did yesterday.

I have Craftsman 42" 917.273634. Exact scenario happened to me. Could start w/o problem, but as soon as "just started" to let up clutch OR as soon as engage blades, the engine would cut off. Important to note that it was clear this was electrical (switch) and not a clogged or locked mower because the engine would kill immediately - before any mechanical action could take place. I was also able to quickly press on the clutch or disable the blade engagement, and the engine would speed back up to normal.

The key here is that (at least with this Craftsman mower), THE SEAT SWITCH IS NOT NECESSARY TO START THIS MOWER.

How do I know?? You can test it. (1) Put mower in NEUTRAL so you don't end up breaking your neck, (2) do NOT sit in the seat; i.e., stand up or stand to the side of the mower [in NEUTRAL and w/o your feet under mowing deck], (3) press the clutch pedal down w your foot, and (4) start the mower. While still standing, gently release the clutch or engage the blades. If your engine cuts off immediately, then it is highly probable that you have a bad seat switch (as I did).

How to fix?? First just try to disconnect the seat switch and reconnect. You can clean/blow out the switch contacts too if you want. Sometimes (as for me yesterday), just disconnecting/reconnecting the switch contacts was sufficient to "fix" this problem.

If that doesn't fix it, then you might need to start looking at wiring or a possible relay or cleaning other switch terminals.