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View Full Version : Stihl 4 mix starting problems POSSIBLE SOLUTION



Chris B
14-01-2012, 12:14 PM
I know Stihl has a terrible rep for starting issues especially on a hot day but I’ve found the reason (for me anyway) on the 4 mix kombi’s
If you are having the same prob which I know at least a few are by what’s written on here then you will kick yourself for how simple it is

We have two 4 mix kombi’s and never had starting issues.. nearly always first pull hot or cold, but eventually became hard to start.
Anyway after trying everything
( I even rang Stihl and spoke to a technician who thought maybe was ignition module but I knew it wasn’t as both kombi’s had issue. Dealer didn’t fix anything either)
... plug/valves/carby clean/exhaust etc.. realised it was just a blocked air filter..


But the reason why it gets blocked is the issue. It seems to be the breather from the fuel tank is vented to just behind the air filter... so if fuel travels back up the line it gets soaked reducing airflow to engine.. making hard to start (not to mention robbing power)
Seems to be two causes.. if you fill up the tank too much it can force the fuel up the line when you put the lid on .. also hot weather makes the issue worse due to heat expanding air/fuel pushing fuel up the line even more.

That explains why it is even more harder to start after a couple of jobs as the air filter gets more soaked as the day goes on.. even quicker when temps are warm. I’m guessing that usually not as bad the next morning as the fuel evaporates off.. but over time as it uses a 2 stroke mix the oil builds up in the air filter making it worse and obviously doesn’t evaporate.

The worst thing is I always cleaned the air filter but you cannot see the fuel oil inside.. so the whole time I ruled out air filter as the problem.
I realised the problem when I pulled the cord a billion times and it wouldn’t start.. pulled the air filter off .. started first pull

Anyway to fix I soaked the air filters in degreaser and they are as good as new. To stop them getting soaked I fill up before a job (so they aren’t sitting in the toolbox with the heat forcing the fuel out) and when I fill up most importantly don’t fill all the way to the top.. have to leave some air in there.
I find you still have to wash the filters but this problem is now gone. also keep a spare clean filter to swap over on the go.

I’m assuming a couple ppl on here who said they had probs with starting after filling up and also another said that fuel leaked out in the toolbox are caused by the same issue.


(note if your breather valve isn’t working this will also cause this prob)
Also another thing with the 4 mixes if you’ve had them for a while and haven’t adjusted the valves make sure you do as you will find heaps easier to pull the cord to start as it has a mechanical decompression. standard feeler gauges dont fit the Stihl so you can either get your dealer to do it for you or what i did is ordered the valve adjustment kit.. its about $10 and includes gasket / washer and special feeler gauge. i just reuse the gasket and washers and keep the new ones as spares.

Stump
14-01-2012, 03:12 PM
The factory issue filter is a throw away job, and shouldnt be washed according to my Stihl shop. Once the backing material gets soaked with oil,...chuck it. Buy a sponge type one, and wash that regulary Same with all of the Stihl gear, blower etc. My mechanic said most contractors rip them straight out upon purchase, and as a result he has boxes full of them.
The other problems with them can relate to the spark arrestor.

Wombat Garden Services
14-01-2012, 03:24 PM
Anyone got a part number for the sponge type filter ?

4 Gardens
14-01-2012, 04:09 PM
I found on my Stihl blower the spark arrestor was blocking up - unscrewed it and cut the mesh off - no probs now

DavidS
14-01-2012, 09:15 PM
Thank Chris B for that information, I will file in back of mind for when I start having problems with my Kombi unit. It's pretty good at moment.

Chris B
15-01-2012, 10:00 AM
had the same probs with my blower spark arrestor a week after i bought it but since then that's been all good. different setup to the 4mix though so have had problems with the air filter.

regarding the sponge type filters i was actually thinking of cutting up a kitchen sponge and putting it in there but once i worked out the reason why it was getting blocked its been fine since. i just make sure always have a spare clean one just in case.

its such a great machine when its running well so im happy now :D

HPM
15-01-2012, 03:42 PM
You can buy filter foam from various suppliers and cut it to size... I get mine from Clark rubber or Briggs and Stratton make a foam block from the local mower shop. Heaps cheaper than genuine foam filters and you can afford to have a few spares.

happymowin
15-01-2012, 03:51 PM
EXACTLY WHAT HAPPENS TO MY FS130 - the filter gets full of oil/fuel, the fuel evaporates, and youre left with an oily filter which wont start.

i just blow the filter out with the blower when i want to start it, i dont use it all the time.

have to ask the shop about the filter like you said.

thanks for the info - i knew i had the problem but not why

Kathryn
15-01-2012, 04:55 PM
my stihl HS45 had bee really hard to start, even if i took the air filter out and then the other day it started on the 2nd pull. im happy its going again but i wish i knew why.

Stump
15-01-2012, 06:08 PM
The HS45 is a bit like that. Its the hardest thing to start in my kit. Fine once its warm. Usually 3 pulls with choke on, until it trys to fire, then choke off, and away it will go next pull. Mine needs a new filter now, as the blade speed is starting to slow. I pulled it out today and it was full speed ahead. It has the same type of filter as the Stihl 4 mix whippys, with the different backing stuff, that gets choked with oil. I need a sponge type for that one.

Fred's mowing
16-01-2012, 02:49 PM
I know Stihl has a terrible rep for starting issues especially on a hot day but I’ve found the reason (for me anyway) on the 4 mix kombi’s
If you are having the same prob which I know at least a few are by what’s written on here then you will kick yourself for how simple it is

We have two 4 mix kombi’s and never had starting issues.. nearly always first pull hot or cold, but eventually became hard to start.
Anyway after trying everything
( I even rang Stihl and spoke to a technician who thought maybe was ignition module but I knew it wasn’t as both kombi’s had issue. Dealer didn’t fix anything either)
... plug/valves/carby clean/exhaust etc.. realised it was just a blocked air filter..


But the reason why it gets blocked is the issue. It seems to be the breather from the fuel tank is vented to just behind the air filter... so if fuel travels back up the line it gets soaked reducing airflow to engine.. making hard to start (not to mention robbing power)
Seems to be two causes.. if you fill up the tank too much it can force the fuel up the line when you put the lid on .. also hot weather makes the issue worse due to heat expanding air/fuel pushing fuel up the line even more.

That explains why it is even more harder to start after a couple of jobs as the air filter gets more soaked as the day goes on.. even quicker when temps are warm. I’m guessing that usually not as bad the next morning as the fuel evaporates off.. but over time as it uses a 2 stroke mix the oil builds up in the air filter making it worse and obviously doesn’t evaporate.

The worst thing is I always cleaned the air filter but you cannot see the fuel oil inside.. so the whole time I ruled out air filter as the problem.
I realised the problem when I pulled the cord a billion times and it wouldn’t start.. pulled the air filter off .. started first pull

Anyway to fix I soaked the air filters in degreaser and they are as good as new. To stop them getting soaked I fill up before a job (so they aren’t sitting in the toolbox with the heat forcing the fuel out) and when I fill up most importantly don’t fill all the way to the top.. have to leave some air in there.
I find you still have to wash the filters but this problem is now gone. also keep a spare clean filter to swap over on the go.

I’m assuming a couple ppl on here who said they had probs with starting after filling up and also another said that fuel leaked out in the toolbox are caused by the same issue.


(note if your breather valve isn’t working this will also cause this prob)
Also another thing with the 4 mixes if you’ve had them for a while and haven’t adjusted the valves make sure you do as you will find heaps easier to pull the cord to start as it has a mechanical decompression. standard feeler gauges dont fit the Stihl so you can either get your dealer to do it for you or what i did is ordered the valve adjustment kit.. its about $10 and includes gasket / washer and special feeler gauge. i just reuse the gasket and washers and keep the new ones as spares.

Great post Chris, this is what we need more of.
You worked it out yourself, while the dingbats in the shop would'nt have a clue, or dont care?
Cheers Fred.

Tender Lovin Lawn&Garden
16-01-2012, 06:11 PM
Buy a honda there easy to start my son could do it when he was 4

Chris B
16-01-2012, 06:13 PM
Great post Chris, this is what we need more of.
You worked it out yourself, while the dingbats in the shop would'nt have a clue, or dont care?
Cheers Fred.

thanks, i never take stuff into the shop to get fixed but i thought that's what the experts are there for... took it in... picked it up .. took it back the next day.... (did that 4 times) and they couldn't find anything wrong with it so I almost gave up on Stihl's and their rep for hard starting !!

Phil 100
16-01-2012, 06:38 PM
Excellent Post Chris, got to 37 degrees here in Adelaide today, got my FS 90, 4 mix out of the shed this morning and removed the Stihl air filter, didn't over fill the tank, started first or second pull all day. Tremendous thank you.

keljad
06-02-2012, 05:36 PM
being a STIHL patriot, with several STIHL machines (whipper snippers and chainsaws) that I inherted from dad and still goes as good as they did 20 years ago.........Im concerned at this post consideing that I just layby'd a STIHL 4 MIX Kombi unit. As Im in Darwqin, its hot all the time............will this cause me issues, and why is the 4mix different from STIHLs of old that still soldier on as good as the day they were bought (20 years later)

Chris B
07-02-2012, 07:18 PM
Hey Phil, hope you had an air filter of some sort when you were using it! but good stuff.. great machine when easy to start.

keljad, you wont regret it. best thing to do i found with the 4mixes is unless its 10 degrees or less dont bother with the choke. 99% of the time mine start first pull without any throttle or choke or priming.

Im actually trialing a more permanent fix but didnt wanna post it up here in case i blow the engine lol. ive disconected the vent pipe from behind the air filter holder and will block with some stocking or similiar and cable tie to keep dust out. will post an update after the trial ... if anyone can tell me a reason why that's not a good idea please let me know! the way i see it is its a breather like any other tank but instead of getting the air from just outside the tank its getting filtered air from behind the air filter.. so as long as im not letting dirt in anywhere then i think it should be ok .. thats my theory anyway.

happymowin
21-02-2012, 04:56 AM
chris hows this going?

Chris B
21-02-2012, 08:54 PM
so far so good :) basically just vented the tank directly outside rather than to behind the air filter. i noticed on this video that was posted recently http://www.youtube.com/watch?v=yN5BWxXo1cc that the machine has a tank vent that doesnt go via the air filter area so assuming this was the older model as the video is dated 2001.. just watch sometime after the 8 min mark.

so i guess the best fix is to install one of them or replace the current breather.. maybe they wear out quickly or something??

63impala
21-02-2012, 09:12 PM
I got two km kombies and on one of them the airfilter is allway wet with petrol start revs and idels and then wont start again...

Chris B
21-02-2012, 09:18 PM
yeh thats the issue im talkin bout.. sucks. i reckon its the breather thats worn out. change the breather or disconnect it from behind the airfilter and cover so no dust gets in and then when the petrol goes back it wont soak the filter

63impala
21-02-2012, 09:37 PM
Yah it a black cromit on the air breather on the fuel tanks hs 01s have it to...Mabe try that before I take it in...

m287j
23-05-2012, 08:47 PM
Brilliant post Chris B, i'm having huge problems with my Stihl KM90 i bought in November. I've just had the valve's adjusted by my Stihl dealer and again it's having huge problems starting even at the beginning of the day. When i do eventually get it started it takes about 5 mins to get to full revs so you can use it.
I've taken the spark arrester off, now i'll keep monitoring the air filter.

Chris B
23-05-2012, 11:01 PM
Brilliant post Chris B, i'm having huge problems with my Stihl KM90 i bought in November. I've just had the valve's adjusted by my Stihl dealer and again it's having huge problems starting even at the beginning of the day. When i do eventually get it started it takes about 5 mins to get to full revs so you can use it.
I've taken the spark arrester off, now i'll keep monitoring the air filter.

sounds like the same prob to me... just take of the air filter when it wont start next time and if it does start you will know thats your prob!

Chris B
23-05-2012, 11:09 PM
ive got two km130's and have had the carby replaced on both as they had an air leak somewhere (wasnt the primer/diaphragms etc.. something faulty) anyway i found out when i was shopping round for a new one as one was out of warranty that they have changed the carby models they use... they have updated so a certain carby model replaces all previous ones on new machines and repairs / parts.

amyway long story short these things are absolutely THRASHED as they are my main whippy's as well as pole pruner hedge trimmer and they stiHL start first pull and run better than new all day everyday. i was planning on selling and upgrading to newer ones when i had the air filter probs but honestly cant see a need as these things seem unstoppable now i have ironed out the probs

ian
23-05-2012, 11:39 PM
must be chinese copies of stihls if they start 1st time :)

Redeye
24-05-2012, 01:20 PM
stihl gear is made mostly in US, Brazil & China, only the high end chainsaws are stihl made in Germany AFAIK

DavidS
24-05-2012, 04:38 PM
All my Stihl new gear has been made in the USA, says so on the serial number sticker. I have the newer KM90 and no problems starting.

Chris B
24-05-2012, 08:56 PM
must be chinese copies of stihls if they start 1st time :)
imagine how good the chinese copies of the chinese copies are

Chris B
24-05-2012, 08:58 PM
stihl gear is made mostly in US, Brazil & China, only the high end chainsaws are stihl made in Germany AFAIK
yeh seems they are made everywhere
my kombis and blowers are from US, chainsaw and hedgetrimmer germany , trimmer brazil, backpack sprayer columbia lol
wonder which ones they make in china now? or just parts?

Redeye
24-05-2012, 11:02 PM
been lots of online complaints about the newer hedgers coming out of china

St George
25-05-2012, 08:30 AM
A dealer told me only to use the 2stroke stihl brand oil.the other oils leave a residue in and around the exhaust.anyone come across this?

ian
25-05-2012, 08:40 AM
A dealer told me only to use the 2stroke stihl brand oil.the other oils leave a residue in and around the exhaust.anyone come across this?
gee wouldn't have been a Stihl dealer by any chance :laughing:
i use the cheapest jaso fd /iso l egd (50:1)grade oil i can find usually (shindaiwa 1) but was using a castrol oil that i brought reduced to clear from kmart for about 2 years haven't noticed any problems

NLALM
25-05-2012, 01:50 PM
Ian I bought some makita oil 5 litres for under 40 bucks seems ok the mower shop said they were using it without any problem. I used to use only stihl oil till I woke up

Treecat
26-06-2012, 10:04 PM
my fix, all is hidden under the cover and so far it seems to be ALOT better then standard

Chris B
27-06-2012, 08:54 PM
looks good pretty much what i did but great idea using a fuel filter!
what did you do with the hole on the back of the air filter housing?
also what 4mix engine is that? looks like a diff fuel cap to mine

Treecat
27-06-2012, 11:03 PM
130(caps not screwed in as i had to un do it to take the covers off), just cut the hose as short as possible and used a rivet(with the thinner part cut off) to fill the hole. may come up with a more long term solution, but i needed things to be reverse-able :)

Chris B
31-07-2012, 07:22 PM
heres a stihl 4mix troubleshooting and repair pdf for those interested: http://golftechs.us/Reference/4.pdf
suggest saving onto computer in case disappears online!

m287j
31-07-2012, 09:10 PM
Thanks Chris, saved a copy.

PaulG
31-07-2012, 10:07 PM
That site doesn't seem to exist but when you dig around a bit a few other pdf's star appearing in searches.
Just put one up for Shindy trimmers.

Scooby Steve
31-07-2012, 10:07 PM
Cheers Chris, St George i use Shindi oil in mine no probs.

LGGF
15-02-2014, 10:24 AM
Hi Chris, thanks for the post, my Sthil 130 was always hard to start when hot, but learnt to live with it. However, after a really hot day the 130 has developed a fuel leak which is coming through the air filter at a fairly high rate, and I'm guessing that the air breather valve has sh!t itself, can you or anyone else tell me if the valve just pulls out of the top of the fuel tank?

Chris B
15-02-2014, 11:06 AM
It does pull out (very difficultly) but i think it was actually the carby that was issue not the vent in my ones?
anyway since then i have replaced both with newer machines and they seem to have a newer carby on them. no issues whatsoever

LGGF
15-02-2014, 11:31 AM
Thanks again Chris, it popped out ok, with the help of a screwdriver. Fingers crossed it was just the valve.

Treecat
15-04-2014, 10:47 PM
it would of been the valve.. mine was replaced free of charge by the dealer(also got a free service as they did it without permission) expect it to flog out again though :(

mgammon
02-05-2016, 09:40 PM
Hi

Came across this thread, when looking for something else. the most common problem with our small engines both two and four stroke is clogged air cleaners. Here is the best way to clean all your air cleaners, put 2 - 4 liters of hot water in a bucket (the hotter the better) dissolve a cup of powered laundry detergent and let the air cleaners soak for about an hour then swirl around for a bit, rinse in clean hot water, then hang on close line until l dry. You can clean all types of air cleaners over and over again this way without hurting them. Never ever blow out air cleaners with compressed air. My whipper sniper filers turn the water black every time which is a combination of oil and dust.

South East Mowing
03-05-2016, 10:49 PM
Hi

Came across this thread, when looking for something else. the most common problem with our small engines both two and four stroke is clogged air cleaners. Here is the best way to clean all your air cleaners, put 2 - 4 liters of hot water in a bucket (the hotter the better) dissolve a cup of powered laundry detergent and let the air cleaners soak for about an hour then swirl around for a bit, rinse in clean hot water, then hang on close line until l dry. You can clean all types of air cleaners over and over again this way without hurting them. Never ever blow out air cleaners with compressed air. My whipper sniper filers turn the water black every time which is a combination of oil and dust.

Thats exactly how I do it when I have time, works a treat. Unfortunately I often don't have time and thats when the compressed air comes in:laughing: Must say that my whippy's and blowers rarely have many problems.
Its just my Honda 195's that suck all the dust in - especially when I mulch in drier times. Helps a little with only 2 blades

BeetleJuice
25-05-2016, 11:29 AM
Stihl is slowly phasing out the 4 mix line

Scooby Steve
28-05-2016, 06:51 PM
Stihl is slowly phasing out the 4 mix line

NNNooooooooooooooooooooooo.

Scooby Steve
28-05-2016, 06:53 PM
Stihl is slowly phasing out the 4 mix line

Any replacement in the works? Will miss the 4 mix, been good to us.

Anyone using the battery line? And if so opinions?

BeetleJuice
31-05-2016, 07:35 PM
Hi

Came across this thread, when looking for something else. the most common problem with our small engines both two and four stroke is clogged air cleaners. Here is the best way to clean all your air cleaners, put 2 - 4 liters of hot water in a bucket (the hotter the better) dissolve a cup of powered laundry detergent and let the air cleaners soak for about an hour then swirl around for a bit, rinse in clean hot water, then hang on close line until l dry. You can clean all types of air cleaners over and over again this way without hurting them. Never ever blow out air cleaners with compressed air. My whipper sniper filers turn the water black every time which is a combination of oil and dust.

After reading this and trying it both stihl products came back to life like they use to be..

Chris B
07-07-2017, 11:05 PM
The 4 Mix's I have used for the last year or so have never had a single problem! I've never even cleaned the air filter once.. (manual actually says only clean when a noticeable loss of power occurs) they have updated them with a pleated paper automotive style one.
I see they have a km131 & fs131 models out on the US Stihl site. Hoping they bring them out here as I rkn they are the absolute best machine with exceptional power for the weight. New models have a 30% larger tank and a semi auto choke which will make them even better

Scooby Steve
08-07-2017, 11:35 AM
The 4 Mix's I have used for the last year or so have never had a single problem! I've never even cleaned the air filter once.. (manual actually says only clean when a noticeable loss of power occurs) they have updated them with a pleated paper automotive style one.
I see they have a km131 & fs131 models out on the US Stihl site. Hoping they bring them out here as I rkn they are the absolute best machine with exceptional power for the weight. New models have a 30% larger tank and a semi auto choke which will make them even better

Love mine too Chris. As a multi tool they are a really versatile machine. Getting a really good lifespan from ours too. Made me lots of money over the journey with very little overheads to run them and very little down time.

edbeek
08-07-2017, 12:49 PM
I got a KM130 when the KM90 died. Gee it drinks the fuel compared to the 90. I don't find the extra power necessary for the work I use it for.

Chris B
08-07-2017, 02:18 PM
yeah when I used the 130 for hedge trimming or pole pruning its total overkill .. just bounces off the rev limiter if you hold at full throttle
as a line trimmer I find it good to have the extra power on hand