Running my chainsaw out of gas "breaks" it

jennigrey · #21 03/22/13, 11:59 AM

Quote:

Originally Posted by foxtrapper

Personally, I suspect you've got two problems going with your scenario.

#1 is the time it takes to get the fuel mixture up from the tank, through the carburetor, and into the engine. This takes a good bit of string pulling.

#2 is flooding it. 2-strokes in general are right touchy about flooding. With chainsaws in particular, the general rule of thumb is choke on until the saw just burps. As soon as it burps, choke off. It will usually start and run on the next pull or two. Leave it running for a few seconds to stabilize itself. And then you're good to go.

I have pulled it so many times that if I had been pulling a saw instead of the string, I would have gotten the job done manually. Eventually, fuel trickles out of somewhere... the exhaust, I think.

As to #2, this saw is VERY touchy about flooding, for normal starts. Like you say, choke on full for a single pull only. Then half choke or completely off and it'll start in one or two pulls.

What really frustrates me is that it starts great and runs well, so long as I haven't run it out. The first time I took it to the shop in town, he handed me quite a bill. He replaced all the consumables in the saw, including the lines and filter and some diaphragms and I-don't-know-what-all. So the lines should be good. I've pulled out the fuel filter and massaged it to make sure it wasn't just clogged. Each time I took it in, the guy at the shop tried to start it and couldn't start it. So it wasn't just me.

The spark plug is quite wet. Not the slightest bit fouled. Getting good spark.

jennigrey · #22 03/22/13, 12:02 PM

Quote:

Originally Posted by MichaelK!

Don't be so worried about taking your saw apart and doing it yourself. It's not like rebuilding a car engine.

After letting my saw sit for a year, it would not start at all. First thing I did was clean the air filter, spark plug, and fresh fuel.

Still wouldn't start.

Next I traced where the fuel lines routed and checked that none were blocked.

Still wouldn't start.

I dismounted the carburetor from the block, split it open and blew carb cleaner through everything. After re-assembly, the saw started, idled few a few seconds, then died. After priming, it would again start, but would instantly die every single time I pressed the throttle lever.

This told me I had two problems. Cleaning out the carb only solved one of them. The saw was stalling because it was not getting enough gas. I blew carb cleaner through the hose and saw it come out the fuel filter, so the filter wasn't clogged. I also cleaned the sintered brass air-vent. The priming bulb was working because I could press it and watch gas squirt. Finally, I read on the internet that it might be that the fuel lines might be cracked.

I replaced all the fuel lines going in and out of the tank, and it started right up. It's now running fine and back at work.

Gennigray, getting back to your problem, I'd start at your fuel tank and follow the path of the fuel every single step of the way till it enters the engine. Just eliminate any potential problem one by one till you get it working. Note that lines in and out of the priming pump might be two different sizes so the inlet and outlet don't get confused.

I'm embarrassed to say that I did have a quick stab at it the first time it wouldn't start but I couldn't figure out how to get the shroud off. I removed every fastener I could find that looked like it pertained to the shroud and still it wouldn't budge. I suspect that you need to know where to pry in order to get it off. I was afraid of breaking some kind of tab or clip.

jeeper55 · #23 03/22/13, 12:36 PM

I have 2 Sthils never a problem starting them, i use high test and marine sta bil in all my 2 cycle engines and never run them dry before i put them away. most of the time i never get by a couple of months before i half to use them again. the only thing i cant get going is a poulan saw,its getting fuel to carb but not through it.

wannabechef · #24 03/22/13, 12:56 PM

If the crank seals are bad it will start hard...

CarolT · #25 03/22/13, 02:27 PM

Around here, there are stations that carry no-ethanol gas. We try to use that in our 2 cycles. Maybe try that?

simi-steading · #26 03/22/13, 02:45 PM

Those old Mac saws are notorious for having pinched fuel lines when putting them back together... That could cause it to not want to pull fuel well into an empty line... Just a thought...

unregistered41671 · #27 03/22/13, 03:08 PM

Quote:

Originally Posted by simi-steading

Those old Mac saws are notorious for having pinched fuel lines when putting them back together... That could cause it to not want to pull fuel well into an empty line... Just a thought...

I bought one used yrs ago. Cranked it and it ran good. Got it home and it would only run 30-40 seconds. I fooled with it a little and could not get it to run. Gave it to a friend and he replaced the fuel lines and it ran well. He wanted to sell me the saw for $80.00 We had a good laugh about that for years.

foxtrapper · #28 03/22/13, 05:56 PM

From your description, you're flooding the heck out of it when trying to start it after running out of gas. And, from your description, I suspect it's your priming.

Any chainsaw will take several pulls of the string when being started from a dry shutdown. But the carburetor parts are small, and the gasoline gets up there pretty quickly.

Might I suggest that instead of priming it, you try starting it like you would for a normal cold start? As in choke only, no priming, pull until it burps, then choke off. I think you will find it starts better and more reliably.

And lastly, I finally got tired of spending time fighting old saws myself. I threw in the towel and bought a nice new one to replace the collection of old crotchety ones I had. I honestly do not regret it.

KMA1 · #29 03/22/13, 06:15 PM

Buy a german made Stihl.

jennigrey · #30 03/22/13, 06:17 PM

Next time I run it out (which may not happen for a while now), I'll try starting it as per usual, without pressing the priming bulb first.

jennigrey · #31 03/22/13, 06:22 PM

After you've flooded a saw, how do you un-flood it? After running it dry and subsequently flooding it, some of the things I have tried in the past include holding the throttle wide open and pulling it. I also took the spark plug out and let it set a while (a few hours) and then re-installed it and tried to start it.

After flooding it, I've left it overnight and come back the next day and tried my standard starting routine.

Bret4207 · #32 03/23/13, 07:23 AM

Quote:

Originally Posted by simi-steading

Those old Mac saws are notorious for having pinched fuel lines when putting them back together... That could cause it to not want to pull fuel well into an empty line... Just a thought...

That is NOT an old Mcculloch. It's one of the newer Chinese/Taiwan types.

Bret4207 · #33 03/23/13, 07:27 AM

If it's flooding so bad the gas is running out the muffler then the issue is that you're flooding it. A warm saw doesn't need priming usually, even when you run it dry. Try doing as suggested and not using the primer.

jennigrey · #34 03/23/13, 10:28 AM

Cold saw. I only run it dry to store it. Then a couple weeks later, refill and prime a few times.

I'll leave the priming bulb alone next time. I sure never touch it for a standard start.

Bret4207 · #35 03/23/13, 02:54 PM

It may be the primer is just pouring the gas in. A weak spring on the needle or a bad valve seat will allow that. I have a similar issue with an ancient Stihl 041. After 5 pulls the fuel just pours past the needle! If it starts in 3 pulls I'm good till it stops, otherwise I'm toast. Have to pull the carb apart and fix it soon.

jennigrey · #36 03/23/13, 04:07 PM

Monday I'll call McCulloch and see if a shop manual is available. I usually do my own wrenching. I made an exception for the saw because I thought it would be more expedient - just this once - to pay a pro to do the job so I could spend my time using the tool rather than working on the tool. Lesson learned. Better to take the time to learn how to do it yourself. Teach a man to fish, etcetera etcetera.

wannabechef · #37 03/23/13, 06:45 PM

Quote:

Originally Posted by jennigrey

Monday I'll call McCulloch and see if a shop manual is available. I usually do my own wrenching. I made an exception for the saw because I thought it would be more expedient - just this once - to pay a pro to do the job so I could spend my time using the tool rather than working on the tool. Lesson learned. Better to take the time to learn how to do it yourself. Teach a man to fish, etcetera etcetera.

Likely nothing can be done to a lower line saw except replace the carb...thy are designed to be cheap, used and thrown away. May I suggest buying a higher end product that comes with support, parts and technical.

Bret4207 · #38 03/24/13, 08:31 AM

Quote:

Originally Posted by jennigrey

Monday I'll call McCulloch and see if a shop manual is available. I usually do my own wrenching. I made an exception for the saw because I thought it would be more expedient - just this once - to pay a pro to do the job so I could spend my time using the tool rather than working on the tool. Lesson learned. Better to take the time to learn how to do it yourself. Teach a man to fish, etcetera etcetera.

I can find nothing on the 3514 saw- and I mean NOTHING! I did however find a parts breakdown for the 3516 saw. I'm going to take the risk of assuming they are the same basic saw. If so it has a Zama carb, the model number will be etched or stamped into the carb body. It's likely a CU carb. Kits are available and Zamas website has rebuild info. Alternatively you can probably replace the entire carb for under $40.00. Zama carbs are not expensive. That type carb is common on weedwhackers, low end chainsaws, leaf blowers etc.

Here's as close as I could come on a parts breakdown- http://www.barrettsmallengine.com/pa...list211318.pdf

foxtrapper · #39 03/26/13, 05:44 AM

Quote:

Originally Posted by jennigrey

After you've flooded a saw, how do you un-flood it?

Two strokes are not the easiest to unflood. A wankel is worse, but a standard crankcase ventilated 2-stroke holds its own on difficulty.

Standard semi-effective technique is to remove the spark plug, leave it plugged it and let it rest against something so it can spark. Throttle wide open, choke off, yank the string a number of times. Like 20 or so.

The objective is two-fold. One is to simply spray the gasoline out through the spark plug hole. The second is to make the spark plug actually spark. A wet spark plug will short through the wetness and not spark.

Caviat, doing this can result in a momentary fireball out through the spark plug hole. So don't do this with the saw in dry grass. It's a little startling if and when this happens, but it's not particularly dangerous.

Once you've blown stuff out, and the spark plug is dry and sparking, try restarting the saw with no choke and no priming. There's still going to be a fair bit of excess gasoline in the crankcase, so it's pretty likely to burp a bit just on this alone.

jennigrey · #40 04/03/13, 03:29 PM

I sure appreciate all of the ideas, thoughts and advice. After I got my saw back from the shop this last time I used it for a couple of hours, refilling it at regular intervals. When I got done using it, I just shut it off and didn't lean it out like I used to. A couple days later I went to use it and it fired right up. Since then, I yarded out a few logs and have used the saw quite a bit in the last four days. Yesterday, however, it suddenly started losing power and smoking. Within a minute or so it worsened to the point that it wouldn't idle. Then it died and I couldn't restart it.

Thanks to advice received here (and a hefty portion of frustration-induced "I DON'T CARE WHAT HAPPENS TO THIS SAW ANYMORE"), I dug in and got to the carb (a Zama, Bret4207). I took the plate and circular diaphragm off one end, bled what fuel I could out of it. Took out the spark plug and cleaned and dried it. Put the carb back together and all of the plastic parts. Shot a hit of ether into the hole and put the spark plug back in, recapped it. It fired right off and ran for another couple of logs, then did the same thing. I did the little song-and-dance and again the saw fired up and ran but this time it idled way too high and soon thereafter it died.

I think I will try replacing the carb. If that doesn't do the trick, I'll probably shelve the saw. The auto-oiler doesn't work so I'm having to oil it manually. Wish I could afford a new saw.