What is this part on my motor? (ACE?)

What is the part that has all the wires plugged in to it? The bright white part near the top...sorry for the bad pic but I thought it was better when I took it. This is off my John Deere riding mower that im having problems with. ACE has walked me through a couple great ideas but they are ruled out now....about the only thing I havent checked is the part i mention in pic. When I last used it, it worked fine, then when I used it again it ran rough with a plop plop plop idle rather than a brrrrrrrrrrrr  

Looks like an ignition module......I see a primary red wire in the harness.

Unplug the harness and rub the contacts with a pencil eraser or spray them out with contact cleaner.

The clip has been busted off by someone with a screwdriver, so it has been off before. Might just be corrosion in the plug or else the module was a cheap replacement.

Next time it is running, feel that module to see if it is hot. If so, replace it.

Rob, where do you see something broke? When it runs it just runs rough and tries to die after a few minutes....doesnt really run long enough to get hot.

In the center of that plug there is a notch where you would normally see a finger that needs to be lifted and then the plug is pried apart with a screwdriver.....I don't see the finger.

If the module is bad, it will get hot very quickly as the wiring is shorting out inside the plastic.

Looks like the voltage regulator. Black wire should show 12vdc with motor off 12vdc  to 14vdc when running.

I'm sure ACE walked you through it, but you just have to confirm 3 things.

1. Does fuel reach the cyclinder?
2. Does the cylinder have compression?
3. Is there a spark?

The fact that it starts and tries to run tells me you have all three, so it is a vacuum leak, weak pump, or week ignition coil / module.

Test the pump by sticking the hose in a glass jar and watch it spurt when when powered on. Strong stream....good to go.

Test for vacuum leak by spraying carb cleaner along the gasket surfaces...if the idle goes up, leak found.

For spark, remove plug and ground it while turning it over to watch the spark profile. If it is the module, spark will be very weak or sporadic. A weak spark can start a motor, but it can't ignite the fuel / air mix under a load.

We used to pull the plugs out of rival's cars and bend the straps down so there would be almost no gap for the spark. The cars would all start right up, but once you hit the throttle they would stall out.

Won many street races that way......just for bragging rights and not pinks though.

Oh man, I should have tried Google.......

https://www.google.com/search?q=john+deere+voltage+regulator&espv=2&biw=1440&bih=809&source=lnms&tbm=isch&sa=X&ved=0ahUKEwiYiuCxvNXJAhVD2SYKHTt4C-gQ_AUIBygC#imgrc=vidgJBH3YPSuAM%3A

Too many years seeing voltage regulators internally with the alternator instead of separate.

Either way, you don't have a good spark.

Has a new plug and gaped correct...cant find an air leak while spraying....getting good clean fuel with NEW filter...Have good compression...motor has been checked (pulled apart) by a certified John Deere Mechanic who checked all the basics while he had time....he can fix it in the spring but I cant wait. He seemed to think electrical.

Wow, you definitely covered the usual suspects, so yes, must be electrical.....or else a banana in the tailpipe.

The only thing left that I can think of is the governor. If it is ok until you put a load on the motor then that could be it. Could be a spring broke on the linkage. Look at the linkage on your tm should be 2 springs one on the rod going to the carb . the other is a bigger but shorter one that connects to the governor and throttle control if that spring is broken that could be the issue.

ACE....running out to check now. going to look that Rectifier Regulator over too.

Now I cant get it to start. This thing is driving me nuts and exactly why im not a mechanic...I have little patience.

It ran well the last time and when I parked it for about a week I tried to start it when a big backfire happened then all the trouble started

Did it backfire out the exhaust or back through the carb?

If it fired back through the intake, it might have damaged the carb....like the blow-out valves on Holley Carbs.

Also, a backfire means one of two things....timing is off or fuel mix is way off. Could try pouring some "Sea Foam" additive into the tank and hope it helps unclog a bleeder valve or idle jet.

If it was me, when I encounter anything that might be fuel related, I remove the carb and hose it down with carb cleaner. I don't take it apart, just soak all the linkages down and get down into the carb's throat as well.

It often does the trick without having to do anything farther and since you didn't open up the carb, there is no chance of screwing up the factory settings.

exhaust....It almost sounded like something crawled into the exhaust and was blocking good flow. Timing is not off...he ruled that out....he pulled the carb and it was a little dirty but didnt have any suspicions. I may revisit the fuel area again as I don't recall checking it very thorough.

So, we are back to the banana in the tailpipe scenario eh?

Is there anything plugging up the exhaust? That would sure cause all those symptoms pretty easily....

just a potato but I doubt that is hurting anything.....I need to check and see if anything may have crawled into it.

You could take the muffler off. It will be very loud but it will rule out the muffler assy being blocked. Just don't break the bolts off. Lube well and work the bolt back and forth a little at a time until you get it out.

May try the muffler to see if any probs there....checking fuel as well.