So this isn't the Techumseh forum but I'm desperate!
 

Incredibly, I can do a few DIY repairs on my MBs with relative success, but I can't get my freakin' lawn mower to start! I hate to have to go out and buy a new one because any that have the same features are close to $400! Mine's only three years old anyway!

It's a 6.75HP Sears Craftsman. I changed the oil, spark plugs and filter. Had to replace the whole pull starter unit a few months ago, and after the stock transmission engagement cable broke twice, retrofitted with a homegrown aircraft cable.

This year, the mower requires about 1000 tries before it starts. I have to set aside about 45 minutes just for the starting ritual!! I also use fuel stabilizer. I have a compression gauge, but I don't know what readings I should be getting.

Anyone here have a clue what is going on? My right shoulder is incredibly sore!!!

I was actually trained by carburetor and Briggs before going the Mercedes route.

I would start with fuel. 99% of all starting problems with small engines have to do with fuel (or lack there of). One quick way to check is to take off the air cleaner and put your hand over the air inlet and give it pull. IF it fires off, you have identified that you have a fuel problem and have to go into the carburetor and see where the restriction is.

If fuel is not the problem, check on the ignition system.

The only weird thing I have seen is a camshaft spun on the gear. You could not tell it was out of time until you set it beside the new one.

Does it have overhead valves - check valve adj if it does - easy job. How old is the fuel in it. You may want to remove all of it and replenish with fresh fuel. Check the fuel filter if it has one. I have even removed the air filter and poured a small amount of fuel into the carb to see if I could make it run. Is the fuel turned on?
To check for fire - remove the plug, attach the plug wire to it, lay the plug on the metal part of the engine and pull the cord. Watch for spark. If it is ok then like Benzmac says - it is in the fuel system. Worst case - you may be in for removing/cleaning the carb.

Hi G-Benz,

I always use a shot of starting fluid for the stubborn yard equipment. I love that stuff and have never had a problem. I think that when those tools sit outside in a shed and are subject to condensation, they're just not going to start easily. On the other hand, my (fairly new) lawn mower and chain saw start easily every time. Who knows?!

On my old lawn mower I had a similar problem, but that good ol' starting fluid bailed me out every time (I used it for 10 years like that). A can of starting fluid is about 2 bucks and will last over a year!

Try tightening the head bolts. A/C engines are famous for loose
head gaskets.

Thanks everyone. I guess I should have mentioned it is a push mower with a 4-cycle engine.

Compression seems fine, and I am definitely getting spark. I have a can of starting fluid, but it did very little, if not anything.

So as Benzmac pointed out, I probably have a fuel problem. I did dump the last of the fuel left in my 5-gal. gas can.

I will have to borrow a mower this weekend, and then I will drain the tank and remove the carburetor. Hope this will do it.

Or...maybe it's the OVP?

Did you try push starting it?(just kidding):)

Since Daimler is Mercedes related...

I've got a 1981 Steyr/Daimler/Puch moped which, unfortunately, has a two-stroke motor. I agree with the others on checking 1.) spark, 2.) fuel, 3.) compression. You also have to check/clean the exhaust port and exhaust system.

Jeff

http://www.mopedsonline.com/photos/gallery1.htm

Here's a pic of my bike. It's the Magnum MKII Limited Edition. Top speed is/was 55 mph.

Jeff

I too have suffered sore-shoulder-syndrome with a nearly new 6 hp Sears mower owned by a friend. It took a while to figure it out but it's a 2 pull process now. It was due to lack of fuel, so to speak. I don't know if the prime assembly has a leak or what but it doesn't work with "2-3" pumps-period. Try ignoring the admonition about not priming more than 2-3 pumps. I give it a brisk 25 and it has started on the second pull for the last 3 years.

I have a 3.75 Briggs, been running about 9 years now with no problem, other than "hard to start" early in life. I too stuck with the recommended "not more than 3 pumps" on the primer and it was a work out. I quickly learned to give it 5-6 pumps, and now it's more often than not a one pull proposition, even after sitting for the off season (about one month here).

The keyway for the flywheel on most all Briggs engines is fitted with a soft key that will shear in the event of sudden impact, such as the blade hitting a big rock or something. The key shears which changes the timing enough to kill the engine on the next power stroke to prevent further damage.

If there have been some slight impacts over time, the key can shear just enough to throw the timing off and make it very difficult to start. These keys can be purchased almost anywhere that Briggs parts are sold.

While you're checking the flywheel, knock any rust off of it with some sandpaper or some such. Theoretically this rust should have nothing to do with preventing spark, but in real life it seems to make a difference.

Another thing is if you run completely out of gas, then fill it up, you sometimes have to blow into the vent hole on the gas cap to push enough fuel into the feed well for it to start.

Lastly, I am assuming that this is a new enough model that it does not have points. If it has points, adjust them and see that they are perfectly clean and no oily film on the contacts.

Hope this helps, if you still have trouble, email me and we'll go through some more things. My daughter and I race souped up Briggs powered Go Karts, so I'm somewhat familiar with the breed.

Good luck,

Having suffered through the B & S and Techumseh situation for during my adolescent life, I'm absolutely and totally committed to Honda for my power equipment. Use new or stabilized fuel, and they ALWAYS start with 1 or 2 pulls. Over 14 years now... Plus, Honda's one of the only makers of clutch systems so your mower doesn't stop every time you let go of the handle. They ain't cheap, though. Of course, I'd have gladly paid $5 every time a mower was difficult to start BEFORE I owned my Honda...

You should at least be able to get the engine to "hit" a few times by pouring a little gasolene (like five drops or so) down the throat of the carb with the air filter off. Sometimes that will light off the engine enough to get the fuel flowing again.

If you can't even get the engine to hit this way then there are deeper problems. But fuel delivery is a typical problem.

Ken300D

It is much quicker and easier to simply blow through the gas cap vent hole to force fuel into the well, than to remove the air filter and prime it. When you're trying to start the engine quickly to get to the line for your heat, it is the only way that's quick enough.

Good luck,