500i Hot Start Problems & Solution

[vision976]

I've been cutting deadfalls on jeep/motorcycle/snowmobile trails on sunny days where the temperature in the shade is 75 degrees F. In the sun, it is much hotter, but I don't know what temperature. I had my MS201T and my 500i both get hot enought to boil the fuel in their tanks and refuse to start. My ancient McCulloch mini-mac does the same thing in the summertime as well. It gets so hot that it will boil fuel in the tank and refuse to start. Sometimes, when it has begun to get too hot, I am able to start it by adjusting the choke to be about 3/4 on and pulling the starter cord repeatedly until it fires. Then by simultaneously manipulating the choke and the throttle, I can get the RPM's up in the high range, where the fan seems to pull enough air to cool the engine enough to run properly for a few more cuts. Eventually, the saw will refuse to start and I have to let it cool down for quite a while.

Yesterday, for the second day in a row, the 500i became balky and would not start because it became too hot. With no choke to set on the saw, I thought about how the fuel primer bulb works to pump fuel through the fueling system and I thought maybe if I repeated pressed the primer bulb, it would flush cooler fuel through the fuel system and enable starting.

This turned out to be the solution to my hot start problems in the 500i. I thought I might be flooding it, but that was not the case. I would press the bulb 3 or more times, sometime 6 times, and then I could start the 500i and use it.

The MS201T does not have a choke to adjust either, just the small lever on the control handle, which one rotates back, locks in the "start" position and then pull the cord to start. I suspect it is actually moving a choke plate in the carburetor, but I've never had the saw a part to verify that. I attempted to manipulate the small lever as if it were a choke, but was unable to get the 201T to fire, gave up, and put it aside. When I got home later in the day, both saws started fine once they were cool.

Just wondering what other 500i and MS201T users have experienced with hot start situations and is there a way to get the MS201T to start when it is hot?

 

[user 122190]

I have highlighted this problem before.

I found that it is mostly a problem with running the longer bars on the 500i.

https://www.arboristsite.com/threads/stihl-500i-fast-idle-and-overheating-bar-and-chain.360589/

 

[vision976]

The 500i had a 20" bar on it, when I was experiencing the hot start problems, so I'm don't think bar length was a causal factor in this case. I've run it with a 32 inch bar for a whole day and never had any oiling problems. But most of the stuff I was cutting was less than 16 inches in diameter on that particular day.

 

[user 122190]

The 500i had a 20" bar on it, when I was experiencing the hot start problems, so I'm don't think bar length was a causal factor in this case. I've run it with a 32 inch bar for a whole day and never had any oiling problems. But most of the stuff I was cutting was less than 16 inches in diameter on that particular day.

Hmmmmm.... Then I've no idea what might be going on. Just exhaust all possible variables before taking it to a shop, unless it is under warranty. I would suggest, since this is happening to 2 saws, the common component might be the gas. Flush them and mix up some fresh mix and simplify the environment, cold air, seasoned wood, short bars, etc. Good luck!

 

[mountainlake]

You could try setting them in the shade and letting them idle a couple of minutes to cool down. Steve

 

[Sierra_rider]

I've never really had many issues with re-starting my m-tronics or my 500i in the heat. The only saw I have issues with is my mk1 550xp, which is a common issue on that saw.

The only time my M-tronics are a bear to start, is if I run them out of fuel. The first burble I hear, I stop cutting and fuel it up. The other day, I was using my 400 when it started running out of fuel. Instead of shutting it off, I tried to finish up the cut and ran it til it was dying. It was a real PITA to restart after that.

Something I've always done just out of habit, is let my saws idle for at least 10-15 seconds before shutting them off. It's not much, but maybe it helps shed a few degrees before you shut down and the tank absorbs the rest of the heat. Also ethanol has a lower boiling point, just another reason to run ethanol-free if you can. It isn't always possible, but I try to run non-ethanol stuff when I can.

 

[vision976]

I always run ethanol-free premium fuel in all of my two-stroke engines, snowmobiles, chainsaws, brush-cutters and blowers. I add stabil to it, too, for some of the machines may sit for months before they are used again.

I was cutting at about 5700 ft, so over a mile high, but I don't know what difference the elevation would make in terms of hot start difficulties. I do have to adjust the carburator high speed needle on my mini-mac saws; a change in elevation of several thousand feet mandates adjustments to lean it out, or enrichen it, depending upon the altitude, but both the MS201T and 500i take care of that automatically. (although the MS201T does have adjustment screws)

I'll try the idling for a while before shutdown, to see if that helps. When I cut in the spring, fall and winter, I don't encounter the hot start problems, it seems to only happen in the summer. I carry the mini-mac saws in the early winter to clear deadfalls from the snowmobile trails. If I'm cutting big logs with mini-mac, I will place it in the snow to cool it off between cuts as I wrestle the cut chunks off the trail. That seems to help avoid overheating problems. The little saw works pretty hard getting through a 20 inch fir.

The fact that all three saws will boil the fuel in their tanks after they've been used for a while on a hot day and then become difficult to start, just seems to be a common problem, at least in my experience.

I seemed to have figured out the way to get the 500i to start, when it is hot, using the fuel bulb liberally.

 

[singinwoodwackr]

I've been cutting deadfalls on jeep/motorcycle/snowmobile trails on sunny days where the temperature in the shade is 75 degrees F. In the sun, it is much hotter, but I don't know what temperature. I had my MS201T and my 500i both get hot enought to boil the fuel in their tanks and refuse to start. My ancient McCulloch mini-mac does the same thing in the summertime as well. It gets so hot that it will boil fuel in the tank and refuse to start. Sometimes, when it has begun to get too hot, I am able to start it by adjusting the choke to be about 3/4 on and pulling the starter cord repeatedly until it fires. Then by simultaneously manipulating the choke and the throttle, I can get the RPM's up in the high range, where the fan seems to pull enough air to cool the engine enough to run properly for a few more cuts. Eventually, the saw will refuse to start and I have to let it cool down for quite a while.

Yesterday, for the second day in a row, the 500i became balky and would not start because it became too hot. With no choke to set on the saw, I thought about how the fuel primer bulb works to pump fuel through the fueling system and I thought maybe if I repeated pressed the primer bulb, it would flush cooler fuel through the fuel system and enable starting.

This turned out to be the solution to my hot start problems in the 500i. I thought I might be flooding it, but that was not the case. I would press the bulb 3 or more times, sometime 6 times, and then I could start the 500i and use it.

The MS201T does not have a choke to adjust either, just the small lever on the control handle, which one rotates back, locks in the "start" position and then pull the cord to start. I suspect it is actually moving a choke plate in the carburetor, but I've never had the saw a part to verify that. I attempted to manipulate the small lever as if it were a choke, but was unable to get the 201T to fire, gave up, and put it aside. When I got home later in the day, both saws started fine once they were cool.

Just wondering what other 500i and MS201T users have experienced with hot start situations and is there a way to get the MS201T to start when it is hot?

Same experience with the 500…several pumps and got it restarted. Not consistently but at least I could use it.

 

[cookies]

The Primer bulb is supposed to be used to flush cooler fuel through the carb to remove vapor lock, standard carbs might need adjustment richer to aid cooling. Removal of the starter recoil to check and clean buildup out of the cylinder fins, fan area and between the handle and cases will help decrease running temps by increasing air flow across the case and cylinder fins. Setting the saw down and letting it idle a minute or three is another good practice on hot days. Another idea that may help is burping the fuel tank to remove pressure to help drop the temp the fuel will boil at.

 

[sawfan123]

The primer bulb is to build pressure ( like1.4 Psi) Not so much a “ primer”.
Once the engine starts, crankcase pluse takes over, so……
it sounds like the system is bleeding down. You would think the opposite would happen in the heat.
Some 500i’s start without pumping. Some don’t. Cold.
Never heard of a problem with the TS 500i.
Guess whatever works.
Thanks for the info.
As for vapor lock, Guess its possible. But with 90 + octane?
There is a test for the pump and injector to check bleed-down.
So, it must be important.
Again thanks for info.

 

[mountainlake]

Another thing that would cause a lot of heat is lugging the saw down too far, try and keep them somewhere around 9000 to 9500 rpm. Steve

 

[501Maico]

It's good your primer still works. I have been running my Makita recently at 90F and the primer bulb also stops working.

 

[Long Bar 60]

So I have heard that there is some sort of sensor built into the "off" button that causes the hard starting. Just put a new button on yesterday and will be cutting timber in semi cold weather tomorrow, 10" of snow but above freezing from about 10:00 AM until quitting time. I've been running a non Mtronic 661 that runs and starts perfectly but I'm going with the lighter 500 as my knees and back are killing me. I'll see if there's any starting problems tomorrow and post when I get a chance.

 

[Long Bar 60]

Well, for what it's worth the 500 ran perfectly yesterday. Max flow, bark box and new button. Shut it off immediately after the back cut on a 4+' doug fir. Gassed up and started first pull.

Trouble is that I had hard starting problems when the saw was brand new. You know what? This saw reminds me of my wife. LOL

 

[Long Bar 60]

Another day of flawless performance. Maybe there's something to the "off" button thing. Won't be cutting again until after Christmas. Poor me. I'll be skiing for the next 4 days.
I think I prefer the 500 over the 661 for typical cutting conditions around here. Lighter, almost as powerful and quicker off idle when limbing. Plenty of limbing too as the primary processor is down and we're using a smaller Tigercat with a Waratah head that can only handle a 22" butt diameter. My back feels it too.
Oh, the switch was $24 plus tax.

 

[woodfarmer]

Speaking of backs, threw mine a month ago. Was ok last weekend so run the splitter for a while. Could hardly move Tuesday and I just picked up my 3rd 500i on monday I sold the 066, 046 and 460 last winter as they were getting a little too heavy.

 

[user 122190]

Speaking of backs, threw mine a month ago. Was ok last weekend so run the splitter for a while. Could hardly move Tuesday and I just picked up my 3rd 500i on monday I sold the 066, 046 and 460 last winter as they were getting a little too heavy.View attachment 1043551View attachment 1043552

I miss my 500i being new and shiny. FWIW them Magnum stickers kick the saw to a whole new level.

https://www.arboristsite.com/threads/first-mod-to-the-500i.357880/#post-7672763

 

[Husky77]

Does anyone bother to read the manual, I cant speak for Stihl but presume their coverage would be similar to Hisqvarna. I seen in many forums people having trouble starting 550xp, especially when warm/hot. The instructions are very clear and if followed to the letter the saw starts no problem.

 

[lone wolf]

I've been cutting deadfalls on jeep/motorcycle/snowmobile trails on sunny days where the temperature in the shade is 75 degrees F. In the sun, it is much hotter, but I don't know what temperature. I had my MS201T and my 500i both get hot enought to boil the fuel in their tanks and refuse to start. My ancient McCulloch mini-mac does the same thing in the summertime as well. It gets so hot that it will boil fuel in the tank and refuse to start. Sometimes, when it has begun to get too hot, I am able to start it by adjusting the choke to be about 3/4 on and pulling the starter cord repeatedly until it fires. Then by simultaneously manipulating the choke and the throttle, I can get the RPM's up in the high range, where the fan seems to pull enough air to cool the engine enough to run properly for a few more cuts. Eventually, the saw will refuse to start and I have to let it cool down for quite a while.

Yesterday, for the second day in a row, the 500i became balky and would not start because it became too hot. With no choke to set on the saw, I thought about how the fuel primer bulb works to pump fuel through the fueling system and I thought maybe if I repeated pressed the primer bulb, it would flush cooler fuel through the fuel system and enable starting.

This turned out to be the solution to my hot start problems in the 500i. I thought I might be flooding it, but that was not the case. I would press the bulb 3 or more times, sometime 6 times, and then I could start the 500i and use it.

The MS201T does not have a choke to adjust either, just the small lever on the control handle, which one rotates back, locks in the "start" position and then pull the cord to start. I suspect it is actually moving a choke plate in the carburetor, but I've never had the saw a part to verify that. I attempted to manipulate the small lever as if it were a choke, but was unable to get the 201T to fire, gave up, and put it aside. When I got home later in the day, both saws started fine once they were cool.

Just wondering what other 500i and MS201T users have experienced with hot start situations and is there a way to get the MS201T to start when it is hot?

Are you using crappy pump gas? If so try some VP 94.

 

[juanroberts]

As a dirtbiker, I can say that I had a boiling over problem and have come to a couple of conclusions. One is to not store Winter gas by using it all up before Spring is over. Winter gas is more volatile so that cars can start easier in the cold. I can also just run fresh gas in my saw in the summer. The other is that in the summer I’m really hot in my moto riding gear and I’m less likely to sharpen the chain. However, a sharp chain results in higher RPMs, less heat on the motor, and the kerf is less likely to smoke or risk creating a fire.