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

I've got a 8hp model #155634s tecumseh. Having some major running rich problems. Was wondering if anyone knows where the flywheel magnet should be in relation to the solid state coil. When the piston is at TDC. I had checked the keyway once before and it was fine. But the engine runs very, very rich. It will start up. It will idle just fine. But when you run it up you'll get a short burst of dense gas vapor out of the muffler. It will then run at higher rpm and fairly well (but your eyes almost burn because it's running so rich). If you then idle it back down shut it off, plug the plug. The plug and in the cyl. are wet with fuel. Had different carbs on it, EPA carbs with different jets. So I don't think it's a carb problem. Replaced the head gasket. Checked valve clearance twice. Put a different coil on it. Then today when I pulled the plug after running it. I noticed it was also wet around the plug hole underneath the plug washer and the bottom of the plug washer was also wet. So now I'm wondering if I have a problem with the plug threads in the head. That is keeping the plug from seating tight against the head (even though the plug feels tight when you tighten it down). It idles so well and there isn't any real signs of compression leakage at the plug. But maybe it's just loose enough to drop the compression ratio and keeping the fuel from fully burning. I don't know. I'm really kind of stumped right now. This could be one of those times when there are multiple problems and you don't know it. Back to my original question. Right now when the piston is right at TDC the magnet has completely cleared the coil. Don't know if that is correct. I also pulled the piston out today and found the oil ring and second compression ring end gap were aligned. With the compression ring end gap only 1/2" to one side of the other two. Though fixing that was going to take care of things, WRONG. Tomorrow I guess I will try a different head. If that doesn't work the whole thing is coming apart (again) and I'm going to, I guess check clearance on the rings, piston everything don't know what else to do. Any help would appreciated. I feel like I'm missing something but I don't know what it is.

Disregard looking at the valves,  That all should be good... I was assuming this was a Used engine..Take a little video of how it runs,  Idling,  mid speed and full throttle..

kinda point out what it is doing..   It is very rare that a new engine  fails,  Does this happen with both carbs? (same Symptoms).. I would try a good ND or NGK plug,  The Champ plug that is in it is a resistor plug (and the cheapest thing they make).   I have had those bad from the box at the shop.

Also, take a look at and post a few pictures of your govenor links and set up of the throttle plate,,,

Does this unit have a oil alert on it ? (low oil shut off)...

Ok..

Good Luck,

Friiy

Well this has been a very interesting saga. The engine as I said was purchased from an auction. I've actually purchased 4 of them in different conditions. This one was described as being new, never used. And judging by the way it looked as I described in my last post I assumed the description was correct. It was clean as a whistle. But, when I had the head off today I took a good look and the cyl. walls. They are in great condition, but you can't see any cross hatching. So how does a supposedly new engine not show any cross hatching (accept at the very top of the bore) ? And if it's not new if it had been used / run how in the world did someone get the ports perfectly clean. And I do mean perfectly clean??? Who knows. Anyway, when I went to get a new head gasket I was explaining and talking to the guy about all of this and what things I've been running across with this engine. He said he believed that it was probably the one of both of the o rings on the throttle tube that were bad. And that gas was being sucked by them causing the over rich condition. Made sense seeing as how the engine idles perfectly and starts up pretty well. I hadn't even considered looking at the o rings assuming that they were new. I'm also not that familiar with the EPA carbs and any problems that they may sometimes have. So I pulled the tube out of the carb. the top o ring looked okay. But the bottom one was pretty out of shape it almost looked like it had a small flange on it one the bottom ( I guess from the pressure of the bowl not) . And one side looked a little flat. The top of the throttle tube also looked rough. Almost jagged and saw tooth like. The guy at the shop of course was out of the kit. And the other shop had already closed for the day. So I'll have to wait until next week to get the carb back together and on the engine. Hope that takes care of things. Sounds like it might. Would at least explain why the engine runs fairly well but extremely rich. Also to answer your question. It does not have an oil alert on it. I would love to post some pictures of the throttle / gov linkage for you to take a look at. But I'm having the same problem I read that your having. I don't have a toolbar that is supposed to show up above the message box. Don't know how to fix that problem. Hoping someone will post a fix. I have a Mac running Safari and was thinking maybe that is the problem. Just don't know. Will let you know what happen when I get the carb back on. Would be interested in what you think about that being the cause of my problem. Thanks again for your input I really appreciate it.