3410 has defeated me!

[BrianP]

I'm done! If you've read my "3410 taxing my capabilities" thread, you know how long I've been fighting with this blasted "machine" (other words spring to mind, but this is a family site after all), just to have a functional grass cutting machine. Well, I'm throwing in the towel. I must've pulled the spark plug (Champion CJ8, brand new), 30 times this morning and each time I vice-grip the base of the plug to a convenient ground, I get spark. Each time I put the plug back in...butkus! I've got gas dripping on the ground, but still it refuses to fire. I played with the points for about an hour adjusting ... re-adjusting ... still nothing. So now what you may be wondering? I'm taking the @#$%^&*%$#@! thing to a mower shop and instructing them to call me when it's running! I may be frustrated (and so mad I can't see straight), but I refuse to buy a Japanese POS from a big box store. May as well throw away more money on something that still says Made In USA on it in places. In the mean time, I'm letting the grass grow. I hereby refuse to use a hand mower for anything other than trimming. Perhaps a kind-hearted neighbor will take pity on my plight and volunteer to do it for me. We do live in that kind of neighborhood after all. I'll check back in when it's been fixed. Time for someone else to get an ulcer over this thing.

[acfarmer]

Get a decent brand spark plug it may cure your problem

[MPH]

If a CJ-8 is all you've tried for plugs try a Campion H10C before you toe it in. That's all I run in mine and never have had a plug problem in the 7-8 years I been playing with these ole Briggs. CJ 8 are lawn mower plugs, you have a garden tractor.

[BrianP]

Okay, one more shot. 8C I'll try another brand. Any recommendations? Other than the H10C mentioned by MPH? I'll make a parts-run later today. Thanks for the info by the way.

[JimDk]

Brian, I agree with acfarmer. Get ANY other name brand of spark plug. Your plug may be shorting to ground under compression. It's worth a shot before you spend any more money. Good luck, Jim

[Gary]

Autolite's have worked well for me. I don't know what to use in your Briggs, but they've worked well in my Kohlers.

[midnightpumpkin]

Did you try spraying starting fluid in the spark plug hole? It should at least fire a few times unless there is a severe valve problem. Does it have compression if you hold your thumb over the plug hole and crank it? Don't give up yet! John U

[BrianP]

Greetings, I got an Autolite (as recommended), and tried that instead of the Champion, with the same results. :( Here's a picture:

The Autolite isn't exactly the same as the Champion, but close enough I figured I'd give it a try. The results were the same although (in my unscientific visual comparison), the Autolite did have a better spark. For what it's worth, I checked [url]http://www.sparkplugs.com[/url], and their cross reference to the Champion H10C was an Autolite 4316 so I'll pick one of those up on my way home from work tomorrow. I held my finger over the spark plug hole and I've got all kinds of compression, not surprising after my rebuild. Then I shot a short blast of starting fluid into the hole and put the plug back in. The engine sort of sounded like it tried to fire a couple of times, then back to just cranking again. Sure glad I charged the battery ;) So where does this leave me? I've never heard of an engine where the plug wouldn't fire under compression. Is there such a thing? If so, what's the cure? I've reached the limits of my knowledge at this point so feel free to chime in.?

[Kent]

I wonder if you might have a sheared flywheel key, and the timing is way off on when it fires...

[dentwizz]

Ohm meter your points assembly. The resistance across the points should be near nothing, less than the spark plug. If not, the spark will be weak and not fire propperly under compression.

[BrianP]

Kent, The flywheel key is fine, I just assembled this engine after a rebuild and both the key and keyway in the crank (and flywheel) were just fine. The ohm meter test sounds promising. I'll try that tomorrow night after work. If I understand this correctly, I read across the points while closed? And a sincere thanks for all the help/ideas. This problem has taken frustration to a whole new level for me. As others have frequently said, the membership fee of $10 bucks is money well spent if you're in this hobby.^

[Robert_Rainwater]

My own personal opinion, but I wouldn't put a Champion plug in anything, they make a fairly desent sinker. ( in my opinion )I use, in my B&S engines only NGK. I have had plugs that would not fire under compression. Again, this is only my opinion. (2 cents worth) Robert

[HubbardRA]

Use the resistance measurement across the points. I have been bitten many times. Points tend to develop an oxide layer that will prevent proper spark. I usually take the points completely off the tractor, then separate the two pieces. I then use sandpaper to polish the points so that they are bright all over. I then put them back together and make sure that the contacts are seating together squarely. Then I gap the points. I have found that if I don't make sure the points are completely clean, they will jump up and bite me, if not that day, then within a week or so.

[JJ MARSHALL]

are you sure you are getting fuel to the plug ? is the plug wet with fuel after trying to start it? JJ

[jrmorrill]

Since the engine 'sort of' fired when you sprayed starter fluid into the top of the cylinder I'd guess that you've got a fuel supply problem, not a spark problem. Perhaps you've got a small piece of crud (technical term) blocking up your needle valve in the carb? Usually signs of a no-spark problem will be a wet spark plug. Wet enough that you'll smell and see fresh gas on the spark end of the plug. If you don't have a wet plug then you ought to spend some time looking over the fuel delivery. Knock on wood I haven't had trouble with my carb so I can't give any specific pointers in this area. Sorry. Jason Landlord 2010

[dav]

just went thru part of the same problems this weekend. my big ten with a 243431 10 hp motor cranked but wouldn't fire. had fuel in the glass settlement filter but would not start. took the point cover off and could see the points sparking so i knew i had power that far. took the needle out of the high speed jet and got nothing. no gas getting to the carb. gas should run out of the hole when you remove the needle because it feeds from the bottom of the float bowl. dismantled the fuel system. had half a tank of water!(tractor sits out near the grapefruit tree under a tarp-if the wind hasnt moved it) the tank itself was coated inside with that motorcycle tank coating stuff about 5 years back. still nice and clean inside. some of the plumbing is brass 1/8 inch pipe but 2 straight nipples are iron pipe and had a fair amount of rust in them. the rust accumulated at an elbow where the teflon tape on the threads had partly covered the end of the nipple. system clean, new fuel, instant start. only ran for about 3 minutes before it started backfiring and stalled but that's next weekend's project(will take me that long to find the welch plug!)

[dentwizz]

When I was getting mine running it would fire for a couple of seconds at a time but never sustain up to full rev until I cleaned the points all the way. There was a burr of arc metal that was insulating at random, so it had to be filed off before they would seat properly. You can thank my dad for knowing that test(electrical designer).

[BrianP]

Fuel doesn’t seem to be the problem. When I first attempted to fire it up, I double checked the main metering valve, to make sure the setting was correct. I ran the needle valve in gently until it seated, then when I went to back it out 1 ½ turns (per the manual), the whole assembly unscrewed and gas ran out. So I tightened the main jet and adjusted the needle valve. Also, when I pulled the air cleaner there was gas along the bottom of the carburetor…yep, I flooded it. When I pulled the spark plug I could smell the gas on it, further convincing me that the problem is spark related. When I shot ether into the combustion chamber and re-installed the plug, it “puffed” a couple of times (different sound), but there was no ignition of the ether. I probably didn’t make this clear in my previous post, being tired and aggravated at the time. Tonight’s plan of attack is to install a new Autolite 4316 plug, check the resistance of the points and pull the points to polish them and check them for “square-ness” since I’ve read that is as important as everything else.

[richp]

Did you use an impact wrench when tightening the flywheel nut? I had a flywheel key shear right after assembly because the wheel wasn't tight enough. Sounds like your problem.

[BrianP]

Nope, didn't use the impact wrench. Used my trusty torque wrench and a deep socket I bought just for that purpose years ago. In fact, I've gotten to the point where I only use the impact for disassembly. The more I dwell on things (no pun intended), I think the points are probably the culprit. Unless they're just right they can be real finicky gap wise.

[oldone]

when you rebuilt your engine.Did you have the have the cam and crankshaft out?

[BrianP]

Yes, I did have the crank out (but not the cam), and went to great lengths to make sure the timing "dots" on the two gears was spot on. I learned that lesson years ago.

[ronb212]

check your points and try an ngk bm6a

[SmilinSam]

quote:

---

Originally posted by Kent
I wonder if you might have a sheared flywheel key, and the timing is way off on when it fires...

---

I'd say its a timing issue with the spark . Either a partially sheared key or in the points or something along those lines. I had one engine once in a T-16H that was doing what yours is doing and it was a partially sheared key. Without taking the flywheel off I couldnt see it was only partially sheared. It would run fine when switched over to battery ignition. This told me the points were fine, as was the timing with the cam and crank. Thats when I took the flywheel off and found the key issue.

[BrianP]

Hi all, Got home a little late tonight, but I’ve now installed a brand new Autolite #4316 spark plug to the mix. This is the equivalent to the Champion H10C recommended by MPH in an earlier reply to this post. I checked the gap and it looked fine .030 as per the manual. Then it was back to the points. As I worked on these my mind slipped into a time warp. Suddenly it was 1975 … Dad and I were driven to the edge by a similar situation. Boy oh boy, how we played with these things (back then they were in our A/C B-10 which was unstoppable – when it ran), eventually ending up in my Uncle’s shop where things would be fixed…or destroyed if need be. But I digress. Anyway, the points looked slightly pitted so I pinched some 220 grit sandpaper between the contacts and went to work. Next, I went to some 600 wet/dry sandpaper. Finally, I polished them up with some emery cloth.

Some might cringe that I used such an “aggressive” grit as 220 (Dad always started with the crocus cloth), but I knew I wanted the best possible contact surface, so that was my starting point. As you can see in the following shot, I ended up with a nice polished parallel surface.

Of course, I did the polishing the points thing when this problem first started. When that didn't work, I ran right out and bought a brand new set of Briggs points (albeit made in Mexico), and mounted them. Now with daylight fading, I’ll have to wait until tomorrow evening to report back on my progress. Man I hope this solves the problem.