small engine troubleshooting? Tuffy by troy bilt won't start

The sticker on it says Tuffy.  It's made by Troy Bilt.  It's a cute little gas-powered tiller that does about 10" wide strips.  

Pull on the cord and it turns and softly wheezes but no bruoom boom.  Not even a put.

Not sure how big or what type of engin this is, but it has both oil and gas.  One spark plug.
It's pretty old.

Also, I don't have the vocabulary for these things.  I can see how it is supposed to work and can usually convince them to start, but not this time.

Changed the gas (the tank was empty so we just put new in it).
Checked the spark.  Yes, it sparks.  
Checked the (thingy that goes round to make spark) with the checker thingy that you pulg between the spark and the sparkcord.  looks right.
Put some quick start in it, and it goes for all of 3 seconds.  So spark and starter is okay.
The rabbit-turtle seems hooked up to everything and moves okay (after a bit of loving).
The choke moves correctly.
Air filter clean enough.  Not feeling this is the problem.
Used carb cleaner on the carb thing and this goes for 3 seconds after then quits.

I don't want to take the carb apart if I don't have to.

The smell isn't right after I've been pulling on the cord for a while.  should smell like fuel or exhaust.  smells neither.  

My feeling is that maybe the gas isn't moving through the hose?  

Or that there's some sort of on/off switch I cannot find.   but if so, then why would it go with quickstart?  

What's the next and least effort troubleshooting for this?  

If I have to take the carb-thing apart then I might as well dig that section by hand and fix the thing during the winter.  

Excellent troubleshooting!!!

You're past my level already but I'd also suspect the gas isn't getting to where it needs to go.  There might be a shut off valve/knob as the gas exits the tank.  If there isn't, maybe there's a fuel filter that needs to be checked/replaced.  If there isn't then there might be something blocking the line.

To check all of these at the same time, you can maybe disconnect the gas from the carb and see if it pours all over the ground.  

This sounds like a Pearl thanng!

I'm trying to think about how the fuel pumps.  It's got about 9 inches of tube to get through.  
If I squeeze the tube, it distributes the fuel level in the tank, so I think there is fuel in the tube.  

Normally there is a fuel pump or a little bulb I pump manually.  But this one looks like the engine moving is what pumps the fuel.  Maybe the up-down-thingy (pisten?) creates enough suction to pull fuel into the carb?  

How does it create suction at the start?  Choke?

Memory of the other times I've used this is that it won't idle on normal choke, it has to run at half choke, even when warm.

So maybe it's getting too much air?  Maybe if I could simulate more choke by reducing air to the air filter?  

Stupid idea?

It's very much trying to balance the need to get this area worked and the drive to make the machine do my bidding.  I don't want to put too much time into fixing the machine so that I don't get the garden part done.  

Mike Haasl wrote:
You're past my level already but I'd also suspect the gas isn't getting to where it needs to go.  There might be a shut off valve/knob as the gas exits the tank.  If there isn't, maybe there's a fuel filter that needs to be checked/replaced.  If there isn't then there might be something blocking the line.

To check all of these at the same time, you can maybe disconnect the gas from the carb and see if it pours all over the ground.  

Yep! Hubby suggests you have your finger ready to cover the hole real quick!

The reason I'm loathed to take the carb apart is mostly the fuel line is original.  I'm not sure it would survive and this would be a big snowball of things to fix.  If I get to that part, I need to take a bunch of stuff off and replace.

Any way to get this running for an hour or two now then I can overhaul it during the winter?  

Spray your carb cleaner on the outside of the carb too.
Check for a fuel filter.
It sounds like gas isn't getting into the cylinders.
A little bulb thing is common to prime it, or a choke. If it's a choke, it might be sticky, what's why I said soak the exterior in carb cleaner, degunk the outside.
The fact that it will try when cleaner is put in makes me think either clogged fuel line, clogged filter, or need for meaner gas. Although...
Let me look something up real quick....

https://usermanual.wiki/Troy-Bilt/TroyBiltTuffyCrt640CUsersManual350004.1031642582.pdf
Nope. What I was checking for was my little gas Mantis like that needed 2 stroke oil mixed into the gas. I'm seeing nothing like that.
Check the manual I posted, see if any of it makes sense.
I'm voting clogged fuel line, fuel filter, or choke problems.
I'm wondering if it got damp in the fuel lines when not being used. If so, upping the octane of the gas might help.

:D

Although this is a newer model, does the engine look something like this?

More diagnostics.  

Do you have compression?  If someone pulls the rope and you hold a thumb over the hole it should make a serious effort at blowing the thumb off the hole.  The fact that it will run on starting fluid says yes but it is still good to check.

If you crank for a bit is the spark plug wet with gas when you pull it?  Most likely is going to be dry.  If wet usually it is a float type carb and the needle isn't sealing off.  If dry likely the carb is plugged off inside with varnish but a couple of other steps first

If there is a hose from the fuel tank to the carb, does gas run out it at the carb end if you remove it temporarily.  If no then looking for a fuel shut off valve, fuel filter(likely plugged), debris in the tank, bad fuel pump(small number of engines have) and finally a plugged hose.(usually leaf cutter bees).   Can't work till you can get gas to the carb.  Now if it has a fuel pump check to be sure it will pump gas when cranked if it won't run out on its own.  Gas does run out then likely carb problems.  

Now if you don't have a fuel line and the carb is mounted to the fuel tank directly likely you are dealing with an over flow type carb.  Over flow carbs instead of having a float and bowl have a tube filled with gas by a little fuel pump.  It pumps more fuel than the engine needs, the tube overflows and the extra gas simply runs back to the fuel tank.  There are a number of these but I only really know Briggs and Straton.  Briggs there are 2 or 3 common failure points.  First there is a thin rubber diaphragm with 2 little flats in it under a cover with 4 to 6 screws right on the side of the carb.  If you have it replace it.  They are often bad with no visible damage.  Then on many Briggs there is an aluminum tube about 1/4" to 3/8" in diameter.  It goes from the crankcase to the carb(often right to the diaphragm plate with the screws.  At one or both ends of this tube will be rubber boots.  Look these over for the slightest signs of cracks or damage.  If any found replace the boot.(Need it immediately and can't replace the boot bury it in silicone sealant and allow to at least skin before starting the motor.)  How this system works is the piston going in and out of the crankcase  creates an air pressure pulse up the tub.  The pulse moves the diaphragm.  The 2 little flaps act as check valves so the diaphragm moving pumps fuel to the over flow fuel tube.  The final problem common to briggs is rust in the fuel tank plugging the pickup screen going to the pump.  The cure for this one since you can't stop the rust is to add a filter over the pickup tube.  To make room for it the bottom of a metal tank must be bent down a little creating a small bowl and gap where the pickup goes.  Then go into the parts store and get a long skinny fuel filter sock that would normally be used in the fuel tank of a car.  Cut enough of it off to go over the pickup tube to keep it from becoming plugged.

So now nothing has worked to this point get some Sea Foam fuel system cleaner to add to the gas and a new spark plug.(strongly prefer Sea Foam brand over any of the others tried)  Sometimes a new spark plug will let an engine run when the old plug looks great.  So always change the plug if the old one has more than 15 or 20 minutes on it.  If is a cheap fix if it works and can save you hours of work often enough to be worth the gamble of a couple of bucks for a new plug even if yours is fairly new.  The fuel system cleaner needs to get into the carb to work.  You mix it with the fuel.  But then you need to crank enough to get the mix into the carb.  Usually I run the motor on the starting fluid for a bit using just barely enough to keep it running.  If any gas is making it into the carb 5 or 10 minutes of this will do it.  Now go away for 24 hours and let the sea foam work(You can often make it work faster if you keep trying but this a point where patience is beneficial in labor saved)  If you can get the engine to limp along do so for another 15 or 20 minutes.  There are varnish deposits above the fuel line inside the carb and the sea foam with time and vibration will dissolve them.

Sea Foam

 

John Weiland wrote:Although this is a newer model, does the engine look something like this?

Not that fancy.  Everything's open and accessible.  

It's a very simple engine setup.  A few years older than the one manual Pearl linked to, but closer to that.  

" smells neither."  ---yes, this is classic "varnish" smell I suspect of gas having congealed in the carb.

The engine photo above is not unlike a Predator engine (Harbor Freight) that I recently put on my tiller of similar configuration.  It looks as though it may have a similar slider for opening the fuel line ( so make sure it' in the open position) and then the throttle (often symbolized with turtle at one end and rabbit (run) at the other end of the sliding throttle).....throttle should be nearly top speed in my experience.   As Pearl noted, carburetor cleaners and gas additives (Sta-Bil being my favorite) can help clean out clogged fuel lines and carburetor jets and rescue an otherwise dead engine.  If you can  get your hands on some of that carb-cleaning additive (goes into your gas tank), then the recommendation would be to pull the cord a few times with all settings as if you wanted to start it.  If no start, let it sit with the additive until tomorrow and try again.  By having pulled some of that additive into the carb system, it may work away at the clog enough for it to flow tomorrow.

One last thing....my engine indeed has an on/off switch......you need to have it in the 'on' position to start----'off' simply grounds the magneto so that it can't deliver a charge to the  spark plug.  The fact that you saw a spark suggests that, at a minimum, your current setting is ready to start.   Also, as you and others have noted, the fact that a bit of added gas will run the engine for a brief period suggests bad gas delivery to/through carb. from fuel tank.  I think your pretty close to success with a little TLC and cleaning and hopefully no need to open the carb.

not great photos.  Let's see if they help.

photos worked.

While I was out there, I tried to start it with my hand on the air filter - smell was of burnt quickstart and carb cleaner.  Sound is better, but I don't have the power to cover the vent and pull at the same time.  

Which means air is coming out of the muffler at last.  

But now my head hurts from sniffing a rototiller so I'm going to try troubleshooting later.  

I think you just have to undo the gas line.  Squeeze together the three tabs on the clamp with a pliers and skootch the clamp to the right.  Then pull the line off, maybe using a flat screwdriver to help.  

If gas comes out, stick it back on quickly.  That means your problem is likely the carb.  

If it doesn't come out, work upstream.

This from Hubby:

I see from the photo that your carburettor is the type that has an adjustable main needle to adjust the fuel flow through the main jet of the carburettor.  The adjustment for this is the little screw at the bottom of the float bowl.  The float bowl is the round metal bowl just underneath where the fuel line from the tank connects to the carburettor.  You can grasp the the needle valve adjustment between your thumb and finger.  I would suggest trying to open it (by turning the screw counter-clockwise when facing the head of the screw) by about 1 to 1.5 turns and then give the carb a shot of quick start and pull the handle and see what happens. If it starts and keeps running you may be able to get your job done but eventually you will have to take the carburettor apart and thoroughly clean the insides and then reset the needle valve adjustment.    Vince

Oh, wow, this is a fine old beastie that may have dodged the scourge of planned obsolescence. It is worth fixing. It is also worth money if you want to sell it.

Before removing any clamps on the fuel line, check the "bump" at the bottom of the sediment bowl. This is where crud and water accumulates, by design. On many old carbs, this was a spring-loaded valve and you would just push up (with a crud cup below) and drain the worst of the junk. Use a flat screwdriver, not your finger. That indicates you have gas to that point in the system.

I don't think that will solve the problem, though. It seems like a gummed-up carb. Doesn't help right now, sorry. But it's worth fixing, or selling.

If you touched the button on the bottom of the carburetor, and fuel came out, then the problem is probably a dirty jet within the carburetor. Take a photo or draw a diagram of the screw coming out of the carburetor (with the spring on it). Clean the whole top of the carburetor with brake cleaner, so no dirt falls into the carburetor with the next step. Once you know the direction the screw will be facing when you reinstall it, screw it out one half turn at a time. Make sure you accurately count the turns, as you'll need to use the same number of turns when reinstalling it. You can use a small dot of nail polish on the edge of the screw head to make it easier to count the revolutions. Once it is out, spray it with brake cleaner, and spray a little brake cleaner down the hole you removed it from. Reinstall the screw, and it should run a lot better.

That is a Tecumseh engine.  The screw going up through the bottom is part of the main jet.  The main jet is brass and has a hex bottom to take it out. If  you remove this the float bowl can come off, but I would leave it on. There is a little cross drilled hole in the jet that is usually plugged.  If you remove the the float bowl try not to get carb cleaner on the rubber gasket, it will swell up quickly.  I use an inventory tag wire to clean these out then spray clean with carb cleaner.  I probably fix 50 of these a year.  The new style for briggs and Tecumseh are missing the adjustment, but work the same with the same problems.

Here is a little vid I did to help fix carbs.  If you have any questions just ask me.

Is there a fuel shutoff valve under the fuel tank?