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thank you everyone for your help- this site is fabulous. In the last 4 days I tuned up &/or repaired two weedwackers, two backpack blowers and two lawnmowers! (my stuff, my dad's stuff and a neighbor's)!

Bad news is my dad and I are still down to one working weedwacker between us both and 2 that I can't get working. I already have a thread on the ryobi that I had to put aside for now. This is for the other.

This one I really want to fix, becasue its the only straight shaft >30ccs so its the only one that will take a brush cutter blade, the mugwort is already getting tall and blackberries are starting to creep over the wall.

Machine: Craftsman model 316.795002
sn: 008085248

This had been running great right up until a mouse chewed a hole in the gas tank- yes- chewed a hole! They don't make a replacement part anymore, so I spent a year or two trying every glue, tape and epoxy I could to seal it up, no dice until "shoe goo" which if you've never tried fixes/seals pretty much everything.. so I glued down a scrap of heavy duty PVC over the hole- and viola! It holds!

This weekend I took it apart, replaced the carb, priming bulb, seals, gas lines and filter. I tried to start it and I'm getting a little resistance on the pull cord and a slow retraction, no hint of starting. I pulled the spark plug and the resistance is less, retraction better, but still just a little slower than it should be. I replaced the spark plug (with a new one) and the resistance increased again.

What do I try next? Its been dry/stored for 2 years, perhaps more...

Re: old crafstman brushwacker - UPDATE fixed cord resistance, now what?

pulled plug, pushed 20ccs of a ~20:1 gas oil mix into the plug hole, shook it up, then pulled the cord a couple times and i could feel it loosen right up. Replaced pug and it started on the first try!!

but it wouldn't idle w/o at least some throttle even on half choke...
It does start on every pull- so horray for that.

I'm kinda okay with it stalling right now, becasue I'm afraid that's not enough lube to run the engine yet- it sounds like somebody's shaking a coffee can full of bolts.. and I don't want to do any permanent damage

What would you do? would you add a little more heavy mix into the spark plug hole? Would you run it on a heavier oil gas mix for the first tank? (manual calls for 40:1). In the mean time I'm gonna go check the exhaust.





The recoil is probably just slow due to an old spring/coil- so Im not worried about it.

20 to 1 is a heave oil mix...... heavier than 40 to 1........ 40 parts of gas is more gas than 20 parts of gas.......

40 to 1 is perfect.. I use that all the time..... Your carb needs a good cleaning and or kit.. If it's running on half choke......

Take out all the fuel, and buy some Stihl oil mix it 50/1 and see if it runs on that, if not you may need to have the carb done, (cleaned and setup)

are you guys pulling my leg? or being condescending? I can't tell?

Carb doesn't need cleaning-

The carb, fuel lines, filter, primer and seals were all replaced... brand new parts, brand new gas... (which I am sure I mentioned)

OH MY GOODNESS WHY DIDN"T SOMEONE TELL ME that 40 is more than 20! :confused2: (again, are you pulling my leg?- becasue you know I am the one doing the mixing right?:tongue
the 20:1 was only 20cc's (or 20 ml, or 0.67 oz) that I poured into the spark plug hole to lube the cylinder, pulled it through a couple times (slow pull on the cord), then turned it over and let it drain out....

the machine had been dry for 2-3 years...maybe longer
before I added the heavy mix to the cylinder it wouldn't start at all and I could feel the resistance
after I added the first dose, it started, but there was awful ratteling and stalling- so I knew lubing it had improved the problem... but I didn't think it was good enough to run it that way-
I knew it was not a fuel or air problem, lubing it directly had already helped, so I lubed it again. I pulled the plug and gave it a rinse twice more, WITH 20:1 high % oil to gas ratio, drained it, let it dry for 5 min, replaced the plug, filled it with 40:1 mix in tank

and Dun-duh-nah naaah:
Idles like a star with the choke wide open and no throttle. Problem fixed 100%

I'm breaking your cops a little bit- but its all good natured
I finished the story not to be a show off (maybe a little) or get on your case - I do appreciate that you stopped in to help (even though..)
A lot of things I recently fixed, I did by searching the forum and finding info in previous threads, so I wanted to share the entire experience so the next guy with this problem knows what worked for me.

Oops I guessed I scanned/read that post toooo fast like I do a lot about you putting a new carb on it.... What do you mean by new seals ???

Sorry about the late post post... A customer showed up with a mower that needed a new starter rope.... Way more than that for sure.... When someone brings me a rope fix..... 90 percent of the time the rope breaks by pulling on it too many times because something is wrong with the mower.......

Nope not pulling your leg about the gas/oil mix.......... If you put 1 oz. of oil into a quart of gas then you have a 32:1 mix

A 40:1 mix is .8 oz oil to 32 oz. of gas which is a quart which is less oil than 32:1 mix ..... I use 40:1 mix and tune my carbs to them at that ratio.....

So a 50:1 mix is less oil than 40:1 ETC ETC.........

Plus Tard Mon Ami ~!~!

Am sure you have nice legs, but am not here to pull them...! we all here use Stihl oil now at 50/1 even if the engine needs 25/1 and we have no problems at all and I was only saying give it a try, if its working with you now that's great well done.

When an engine has not been run for a long time the rings & bore go dry.
The seal inside the engine is done with the oil, so no oil = no seal.
Same as when a car boils & stalls, it cranks like crazy for 10 minutes till it establishes an oil film again.

To be precise, the air gets behind the piston ring and forces it into the cylinder and without oil on the rings the air rushes right past the ring.
With old engine that have not been used for a long time it is always good to pull the plug and pour a LITTLE oil down the hole to remake the seal.

Running a blue smoke on two heavy an oil mix is very bad for the engine.
Firstly the holes in the carb are a fixed size and allow a fixed volume of fuel to mix with a fixed volume of air.
However if there is more oil then there is less fuel so the engine runs lean ( counter intuative ) and thus hotter.
The excess oil burns in the hotter engine to make hard coke that can score the piston & trash the engine in no time flat.

So more oil is a no no no.

The opposite happens with a thin oil mix.
More fuel & less oil by volume so the engine runs rich and with todays lean burn jetting , a little richer is a good idea, but don't let the EPA know about it.

Finally forget glue on thermo plastics.
They will weld so easy it is not funny.
However just like metal, you need to use the right plastic.
Most thanks are made from HDPE, as are plastic milk containers.
So it is just make sure both the tank & the repair patch are really really clean finishing off with acetone.
Hit it with a hot air gun till they both look wet then laying the patch over the hole & use a paddle pop stick to push them together & work out the air bubbles.

bertsmobile-
That was FABULOUS.. oops- that was kinda girly.. Am I allowed to scream fabulous on a lawnmower repair site?

How bout cool man, very cool.

I worked off some half-a$$ed logic, based on nothing but assumptions.. thank you for explaining it


and my glue did eventually fail- tried permatex 2 (recommended on a marine/boat site, didn't bond) I don't know why I didn't think to just hot weld the plastic.. Probably becasue I didn't know I can patch from a milk gallon if I need too- that's some expert [blank]

Down here all plastic parts have a little triangle with a number in it.
This is done to allow them to be recycled.
AFAIK the system is universal world wide so you just match the numbers & you are fine.
When it comes to fuel only a couple of types of plactic will stand up to it and the most common is HDPE which funny enough is the same stuff they used here for milk containers.
Very handy cause it is thin so you can cut some strips to stitch up a crack or hole then lay bigger bits over the top.

The trick is getting the plastic adsolutely clean and not roughing the surface cause that traps air prevent the plastic from touching.
So you do it much like applying a decal or wallpaper.

As for girly, no sexism here, you are a mower owner with a problem end of story.

I've seen the number stamp on all kinds of things today- but I've never seen the number stamp on a fuel tank... Its good to know. I don't have a heat gun, but I bet I can pull it off with a blowtorch and a light touch... obviously on a clean dry tank i'll wipe with isoproply...

I think this thing is as old as I am.. and forgive me for sounding like a fuddy-duddy but they definitely don't make 'em like they used to. It doesn't have a build date (and I have no desire to figure out the SN code). I used to borrow this one from my dad before I bought my own - and mine has a 2004 build date. My father probably bought this thing in '82 when dinner parties included spray cheese out of a can, and Lionel Richie was on the top 40 lol!

Spray goo that had a cheese flavour was a product only found in the USA ( thank heavens ).
Doing it with a naked flame is very hard as plastics burn and once it starts to burn then the ends of the molecules will have an O on then and no linger able to join onto another plastic molecule.
The heat just provides enough energy for the ends of the molecules to make them active so when they touch another plastic molecule it joins onto the first one and they are welded.

As an aside, any two metals that are absolutely clean will also weld together at quite low temperatures.
This is why transistorised switching got invented.
At very high altitudes ( and in space ) the oxides evaporate off contact surfaces and the amount of heat generated by the power flowing through the switch ( or contacts on points or relays ) is enough to weld the switched closed.

that is absolutely true - there is definitely a huge difference between melting (physical change) and burning (chemical change) and the blow torch is not the right tool

providing enough heat energy to facilitate the chemical bond between plastics (melt) rather than the O2 in the atmosphere (burn) is really going to take a lot of patience.

but I've used a blow torch to soften110 year old window glazing w/o braking the glass (in March) and managed to bend clear acrylic without singing it. Its Not for faint of heart, and if I hadn't used a blow torch incorrectly before I wouldn't try it on what remains of an obsolete part... but its definitely manageable.

and spray goo cheese was fantastic Burt... it's a cultural relic akin to clovis points

No Way for spray cheese.
Occasionally I get a glut of veggies from the garden and the freezer is full so I pop onto the web for some recipies that use whatever I have as a principle ingredient.
I can not believe the stuff that is put up there, particularly by supposedly women's religious groups, unless it is designed specifically to hasten the time before they get to the pearly gates.
I am sure my weight goes up 20 lbs just from reading them.