sscotsman 132 #1 Posted February 22, 2011 Im wondering if anyone can tell what might be "wrong" with my engine, from two symptoms..Engine is a 1971 Tecumseh H70, 7HP, on a 1971 Ariens snowblower. As far as I know, the engine is essentially all original and never rebuilt. 1. Every time I finish using the snowblower (30 to 45 minutes), when I come inside, my clothes smell strongly of gas. 2. It doesnt like to run on "no choke".. I start up the engine, cold, on "full choke"..then move it to 3/4 choke, then 1/2 choke..but if I go to "no choke" it hesitates a bit and doesnt run smooth.. if I back it off a bit from "no choke" to about 1/4 choke, it runs smoother..so I just leave it there. I dont know if those two things are related or not.. The engine actually runs fine..starts easy, seems strong, no real problems.. the snowblower itself works flawlessly.. But im wondering if something could be adjusted to make it better..I would especially like to improve (or eliminate, if possible), the gas stink.. perhaps its just old age? I know the gas smell means the engine isnt fully burning the gas, but I dont know why, or what can be done about it..if anything. ideas welcome! thanks, Scot Share this post Link to post Share on other sites
Giles 2 #2 Posted February 22, 2011 Sounds like a lean fuel condition. This could be from a dirty carburetor or an intake leak. Knowing how long the engine has had this problem would help. If it just started, I would suspect a carburetor cleaning is necessary. If the problem is getting progressivly worse, I would suspect an intake leak. The intake leak can be diagnosed with WD-40, starting fluid, or just plain water--sprayed all around intake system. If the problem has always been there--a carburetor adjustment may be in order. So the first thing I would do is to replace the sparkplug and then do the intake leak test. Share this post Link to post Share on other sites
Horse Fanatic 49 #3 Posted February 22, 2011 That engine should have an adjustable high speed jet. It comes out of the nut that holds the float bowl on. Try opening the jet while it's running on full throttle and see if you get it to run with the choke off. Share this post Link to post Share on other sites
mr.pipes 4 #4 Posted February 22, 2011 Take a look at the choke and throttle shafts for play/slop. My 605 behaved like that when I first got it running but I did not notice a fuel smell. I have a few old Ariens myself and really like your website. Nice job and thanks for making it. Share this post Link to post Share on other sites
sscotsman 132 #5 Posted February 22, 2011 thanks guys! im fairly new to all this, so even something as simple as dialing carb jets is a bit of a mystery to me! I will take a look at that jet and see if I can get it to run smoother at "no choke"..I will give it a try tonight and let you know how it goes.. thanks! scot Share this post Link to post Share on other sites
squonk 38,921 #6 Posted February 23, 2011 My grandfather had an old Ariens thrower. I'm sure it was pre 64. He loved that thing but around the mid 70's he stripped out the spark plug hole. He traded it in for a new Toro. He hated it. He took it back and got another Toro. I came home from college and he was squawking about the Toro. I said " you could have gotten the head on the Ariens fixed or replaced easy enough." Now he was REALLY mad! :thumbs: Share this post Link to post Share on other sites
cpete1 331 #7 Posted February 23, 2011 Tecumsehs are sensitive to "varnish" in the carb. Not sure about the type of carb you have but I have had issues with 3 tecumseh engines. You might end up taking the carburater off, dismantling it and cleaning it. Places to check will be the Fuel bowl where your main screw is in the bottom and a tiny and I mean tiny hole in the main throat of the carb. You have to take a small wire like 1 strand from a typical piece of wiring you find on a car or tractor for that matter and snake it into the tiny holes in the throat of the carb(use small needle nose pliers) . Spray carb cleaner won't cut it out at first. Once you run the wire in and out, then douch the openings with carb cleaner. Once the passages are open things should smooth out. Its a pain but it will make all the difference in the world. Typical symptoms are, If the choke is all the way off, the engine will surge... Erratic speed of idle. Good Luck, hope it helps Chris PS First, just try taking the fuel bowl off and cleaning it. The float assembly kinda just sits in there but if you're careful and go slow, you shouldn't have a problem with dismantling it and re-assembly. Sounds like your engine idles fine so it might just be varnish and crap in the fuel bowl and the main jet where your main screw goes in. Share this post Link to post Share on other sites
hoppy 0 #8 Posted February 25, 2011 what he said............cleaning these bowl carbs is cake. not much to them parts wise and if you just take your time, some notes along the way, clean everything re4ally good, and put it back together the way it came apart you should be good to go. i was petrified of cleaning carbs once upon a time. after you do the first one and get it running you will be that more confident to do the next one. Share this post Link to post Share on other sites
