FS45 trimmer problem, help!!

[ryans4022]

Yea, i will check that as well since it looks like a teardown is coming!!

 

[fishingdave]

Yea, i will check that as well since it looks like a teardown is coming!!

Hey Ryan did you ever find the problem? I have a hs45 which is the same exact motor it's driving me nuts!!

 

[Thommo]

I would like to know what the problem was too. my Neighbor brought his FS45 around for me to fix because his local stihl shop charged him $180 to work on it and still didnt get it going. I thought it was a carby problem because i got it going for a while by sanding all the gasket surfaces flat, but it still had symptoms of a bad high speed check valve. I went to another Stihl shop to buy a carby and they told me that the carby costs $110 and they would have to fit it as well as fitting a new spark plug, fuel filter and air filter, which would be about $180 all up. They were selling new FS45 trimmers for $199
I told my neighbor to throw the piece of junk in the bin and buy an Echo.
I think they should be called a FFS 45

 

[Stihldoc]

OK,
Chances are that everyone is overthinking this and making work to solve a simple problem. I am a senior tech at a large dealership and I work on hundreds of 4140's each year. The FS45, 46, and 55's (4140 series) are remarkably dependable trimmers that rarely EVER have serious issues. I know that individual trimmers can have weird issues, but the model taken as a whole is darn dependable. I can't tell you when last I saw a sheared key, a failed or failing coil, or other internal engine failure on a 4140 unit. This is not to say it can't happen, but the odds are that it is a carburetor failure. I used to rebuild these little Zama carbs and installed many hundreds of RB-100 repair kits, but no more. The owner says the plug is wet, thats a real clue here folks... has a 3-way check been done to the carb to check the inlet needle & seat and the intake & outlet valves in the purge base? Probably not. Less than a minute with the pressure and vacuum gauge will tell you if the carb is basically solid. Pull the fuel pump cover (side of the carb held on by only 1 screw) and look for any corrosion. If the carb fails a test or has corrosion, don't overhaul it, just replace it. This is a $30 carb and is generally not worth trying to overhaul. At out shop's labor rate, its cheaper for the customer to replace the carb rather than repair it. Again, I'm relying on experience and the unit's track record to GUESS whats going on here. Unless I can properly teat the carb, I don't KNOW. If the unit feels like it has good compression and has good spark, ODDS ARE that a 4140-120-0619 carb will make it run like new again. At our labor rate of $84/hr, I don't fool around with complex diagnostics trying to track down obscure problems that probably aren't there. I love these 4140 units and encourage people to repair them. Its very cost-effective to repair the unit you have if its something simple like the carburetor, and with proper storage, the unit will be dependable for years to come. This trimmer's issue is PROBABLY a carb that is flooding the engine. Thats an easy, economical repair.

 

[Thommo]

The one i worked on definitely had a bad carb. The machining on the gasket surfaces was terrible. It looked like either the cutter on the milling machine came loose or the carb wasnt mounted firmly before it was machined, resulting in the middle section of the pump side of carby being hollowed out and very uneven. i sanded it flat and got the fuel pump working but the carb still had a problem where it sometimes would not idle and sometimes had a flat spot on acceleration, then it would run perfect for a while. $30 sounds about right for a new carb but unfortunately in Australia we are charged $110

 

[HarleyT]

Shipping to Austrailia is @ $13 first class, someone could pop one in the mail to you.

 

[Thommo]

I might have to talk to my neighbor when i next see him to find out if he still has it. last time i spoke to him about it he was ready to throw it off a cliff.

 

[HarleyT]

Looks like the Chinese have started making that carb aftermarket, we can get one off of e-bay dirt cheap from China,
don't know about the quality there though.

 

[Thommo]

They probably come out of the same factory that make them for stihl. The FS45 carb had China cast into and i have seen the same on MS 170 and 180 Carbs

 

[HarleyT]

No, they look like crap, compared to the Zamas.

 

[Thommo]

I just had a look on Ebay. Some have the brass hose barbs and others are only plastic. Under $20 delivered to my post office box.

 

[HarleyT]

Yeah, you can get them cheap.

 

[ryans4022]

Thanks for you guys help, wow I posted this a few years ago. Think I ended up replacing powerhead, I replaced carb with new still no go (even put the carb on a working trimmer and ran fine), checked fw key seals, replaced coil etc. That one whipped me I guess.....

 

[GLN]

Hey Ryans4022, my Dad gave me his FS45 Stihl trimmer and I could not get it to start. Smelled the fuel and could tell it was old. I did a carb tear down and there was a ton of gunk in there. Skipped the rebuild and bought the aftermarket carb from Amazon https://www.amazon.com/gp/product/B00KHKJJO6/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1 . Replaced the Spark Plug, Cleaned the fuel tank and lines. Then put the new carb on which I received in 2 days, and the trimmer would not start. Not even with starting fluid. So I checked the spark plug, and it was good, sparked like a new plug should. Then I went on line and found your post, and was almost at the point of replacing the power head but saw the post from Stihldoc who said your plug was wet. Several others mentioned flooding as well. I pulled the plug and it was wet. I left it out, dried the plug, and waited 10 minutes. Up until this point I had been priming the bulb 3 times and closing the choke then trying to start with WOT. I now opened the choke primed it once and on the 3rd pull it sputtered. After a couple of more pulls it seemed like the low speed was off, so I set it to 2 turns out, and set the high speed to 2 turns out. Finally, I was able to get it started using partial throttle and adjusted the high and low to optimum. I am surprised at how easy this engine is to flood. Now that its warm, it starts on the first pull with no throttle, if I have an issue starting the trimmer when it's cold I will post again.

 

[Hoji]

Hello. I have a Stihl HL45 hedge trimmer which uses the same engine as the FS 55 and FS45.
The trimmer had seen light use over 7 years or so.
One day I was using it when it sounded like it ran out of gas. So I refilled the tank.
It would not start.
Not wanting to mess with it too much.. I just replaced the carburetor and the coil with Chinese replacement parts.
Well... It still would not start.
I took it to an authorized dealer. They couldn't get it started either! Said they were uncomfortable having me buy parts and
put them in when they were not sure if it would work anyway.
It had good compression and good spark. It did seem to be flooded but couldn't even get it to pop even once.

They charged $40 for their opinion. I didn't want to pour money into uncertain repairs either.
Even though I really got curious as to what could possible be wrong with it.
This was the most frustrating machine I have owned. It was always temperamental, hard to start, revving to high, bogging out, etcetera.

Here is what I did.
Bought a used HS55 from craigslist for $80. It took me 4 minutes to pull off the weed wacker shaft and insert my hedge trimmer shaft.
Worked like a charm.. I went around and trimmed all my hedges.... So nice! And now I have plenty of spare parts.

Here is what I learned.
Stihl makes these trimmers in China. Even the original carburetor that I replaced says... "made in China" on it.
I feel betrayed by Stihl... I thought I was buying an American or German machine... Not Chinese junk!

Stihl has lost my trust. There are plenty of other quality brands out there. I plan to get my revenge and avoid Stihl machines on future ventures.

Unless I need a chain saw.

 

[Goofaroo]

Hello. I have a Stihl HL45 hedge trimmer which uses the same engine as the FS 55 and FS45.
The trimmer had seen light use over 7 years or so.
One day I was using it when it sounded like it ran out of gas. So I refilled the tank.
It would not start.
Not wanting to mess with it too much.. I just replaced the carburetor and the coil with Chinese replacement parts.
Well... It still would not start.
I took it to an authorized dealer. They couldn't get it started either! Said they were uncomfortable having me buy parts and
put them in when they were not sure if it would work anyway.
It had good compression and good spark. It did seem to be flooded but couldn't even get it to pop even once.

They charged $40 for their opinion. I didn't want to pour money into uncertain repairs either.
Even though I really got curious as to what could possible be wrong with it.
This was the most frustrating machine I have owned. It was always temperamental, hard to start, revving to high, bogging out, etcetera.

Here is what I did.
Bought a used HS55 from craigslist for $80. It took me 4 minutes to pull off the weed wacker shaft and insert my hedge trimmer shaft.
Worked like a charm.. I went around and trimmed all my hedges.... So nice! And now I have plenty of spare parts.

Here is what I learned.
Stihl makes these trimmers in China. Even the original carburetor that I replaced says... "made in China" on it.
I feel betrayed by Stihl... I thought I was buying an American or German machine... Not Chinese junk!

Stihl has lost my trust. There are plenty of other quality brands out there. I plan to get my revenge and avoid Stihl machines on future ventures.

Unless I need a chain saw.

I get these coming into my shop all time. Primarily FS38, FS45, and FS55 models.
The first few I worked on I kitted the carbs but could still not get them to start or run reliably.
I finally decided to add them to my list of Chinese crap that I won’t work on.

Over time, I had customers come in with these models and I told them it wasn’t worth my time or their money to repair them. I either sold them a used Echo that I had on hand or sent them to buy a new Echo. Problem solved.

In most cases they just gave the Stihl trimmers to me so they didn’t have to take them home. I threw them in my barn. Over time I ended up with a few of all three models that had seen very little use. I decided to bring one back into the shop and see if I could find a fix for these models.

The first thing I noticed was that the green one piece fuel line system was not only a bad design but they deteriorated rapidly. I pulled one off and made an Echo style setup with a three hole grommet and proper fuel line. This enabled better routing and better durability. This alone unfortunately didn’t entirely solve the problem of hard starting and other issues.

I brought two more units into the shop. I now had a FS38, 45, and 55 on my bench. All had strong spark, good compression, clean spark arresters, and the same problem with hard starting, won’t start, won’t run right, etc.

I decided that the issue seemed to be the carbs. I had cleaned them and kitted them but decided to try replacing one with a Chinese EBay carb. The original carb was Chinese
anyway and about $40 at the dealer so I ordered a $10 carb from EBay. It came in, I installed it, and there was no improvement. The project got pushed aside for a few months.

Then I decided to try again. I looked at the carb options on EBay and found a couple of carbs from different sellers. The first one I received was a slight improvement but still not at all something that I would expect my customers to be happy with.

The second one came in and once again I was tired of wasting time on this garbage. A couple of weeks passed and I decided I might as well give it a try. I bolted it on and took it outside. I primed the bulb and it popped on about three pulls. Set it to half choke and it fired up and idled! This was something new. I let it idle a bit with no choke and then pulled the throttle and it responded. I decided to tune the low side a bit and it responded very well as did the high side. I put it in some tall grass and it ran great and pulled nicely.

Still not convinced, I let it sit overnight and the next morning tried to start it. It fired right up like an Echo and ran perfectly.

I decided to order three more of those carbs from the same seller. Two to use on the other trimmers and one to have in stock. I installed the carbs with the same results. I can’t believe I’m saying this but I now have three Stihl trimmers that run perfectly and get used regularly.

I’m certainly not recommending these trimmers but if someone has one of these models I seem to have found a fix. I ran these all summer and not one ever failed to start and run properly.

Here’s a link in case anyone wants to give it a try. I only used the carb and the air filter.

https://www.ebay.com/itm/NEW-Carbur...a=0&pg=2332490&_trksid=p2332490.c100889.m5204

 

[grizz55chev]

I get these coming into my shop all time. Primarily FS38, FS45, and FS55 models.
The first few I worked on I kitted the carbs but could still not get them to start or run reliably.
I finally decided to add them to my list of Chinese crap that I won’t work on.

Over time, I had customers come in with these models and I told them it wasn’t worth my time or their money to repair them. I either sold them a used Echo that I had on hand or sent them to buy a new Echo. Problem solved.

In most cases they just gave the Stihl trimmers to me so they didn’t have to take them home. I threw them in my barn. Over time I ended up with a few of all three models that had seen very little use. I decided to bring one back into the shop and see if I could find a fix for these models.

The first thing I noticed was that the green one piece fuel line system was not only a bad design but they deteriorated rapidly. I pulled one off and made an Echo style setup with a three hole grommet and proper fuel line. This enabled better routing and better durability. This alone unfortunately didn’t entirely solve the problem of hard starting and other issues.

I brought two more units into the shop. I now had a FS38, 45, and 55 on my bench. All had strong spark, good compression, clean spark arresters, and the same problem with hard starting, won’t start, won’t run right, etc.

I decided that the issue seemed to be the carbs. I had cleaned them and kitted them but decided to try replacing one with a Chinese EBay carb. The original carb was Chinese
anyway and about $40 at the dealer so I ordered a $10 carb from EBay. It came in, I installed it, and there was no improvement. The project got pushed aside for a few months.

Then I decided to try again. I looked at the carb options on EBay and found a couple of carbs from different sellers. The first one I received was a slight improvement but still not at all something that I would expect my customers to be happy with.

The second one came in and once again I was tired of wasting time on this garbage. A couple of weeks passed and I decided I might as well give it a try. I bolted it on and took it outside. I primed the bulb and it popped on about three pulls. Set it to half choke and it fired up and idled! This was something new. I let it idle a bit with no choke and then pulled the throttle and it responded. I decided to tune the low side a bit and it responded very well as did the high side. I put it in some tall grass and it ran great and pulled nicely.

Still not convinced, I let it sit overnight and the next morning tried to start it. It fired right up like an Echo and ran perfectly.

I decided to order three more of those carbs from the same seller. Two to use on the other trimmers and one to have in stock. I installed the carbs with the same results. I can’t believe I’m saying this but I now have three Stihl trimmers that run perfectly and get used regularly.

I’m certainly not recommending these trimmers but if someone has one of these models I seem to have found a fix. I ran these all summer and not one ever failed to start and run properly.

Here’s a link in case anyone wants to give it a try. I only used the carb and the air filter.

https://www.ebay.com/itm/NEW-Carburetor-For-STIHL-FS55R-FS55RC-FS55-KM55-HL45-KM55R-FS38-w-Fuel-Line-Kit/162858319268?_trkparms=aid=888009&algo=DISC.LISTINGS&ao=1&asc=20191002092920&meid=c06d9c828cfd4959b8f054f29ccaa154&pid=100889&rk=3&rkt=6&mehot=pp&sd=162858319306&itm=162858319268&pmt=1&noa=0&pg=2332490&_trksid=p2332490.c100889.m5204

$10! AWSOME!!!

 

[Goofaroo]

$10! AWSOME!!!

Yep. Go figure.

If anyone tries this carb I’d like to hear the results. It’s been a few months since I ordered these so hopefully they’re the same.

 

[Hoji]

Thank you for sharing you experience. For $10 I should give this a try. Right now I am just happy to have gotten around the problem.
When I get the time again.. I will give it a try.
In the mean time I will be looking to see it this works for others.

Thank you!

 

[Goofaroo]

Thank you for sharing you experience. For $10 I should give this a try. Right now I am just happy to have gotten around the problem.
When I get the time again.. I will give it a try.
In the mean time I will be looking to see it this works for others.

Thank you!

No problem. I hope it helps others on the forum.