Stihl 500i Hard Start Cold

[StihlsawuserMS361]

I have a new 500i. Dealer filled fuel, pumped 4 times, started, stalled. Pulled again and continued to run, he checked oiling etc, less than WOT. Brought it home, the same. So far so good.
I've been using the saw, but relatively easy for the first 4 tanks. Did cutting, at less than full throttle, then let saw cool completely etc. Lately, it's been starting hard cold, many pulls, then starts, stalls, repeats about 6 times before it will actually run and take fuel. (Book I believe says "press the manual pump bulb at least eight times"). Today ran saw, got pinched in a medium log and shut off. Freed, re-started and continued cutting a few more pieces, then @ idle, chain continued to move, but it didn't seem like the motor was racing or really above idle. Continued to use saw, chain still moving @idle for about 5 minutes between cuts, then it straightened out for about a full tank.
I've read threads here, but nothing really pertains to this.
So my question...how many times should I be pumping the primer for the first cold start of the day? (Ambient temp has been 70's or so) I've tried 4, 6, 8, and 10..
Thanks to all!

 

[huskihl]

The primer is only there to pressurize the fuel system before you pull the cord. If it takes six pumps to pump up the fuel system, anything less than that won’t be enough and anything more than that won’t make a difference. I’ve heard of guys pumping it 8-10 times every time they started it and I’ve also heard of guys not pumping it at all and it will still start but it takes more pulls.

I wouldn’t run it any longer at half throttle. The more you do that with electronic controlled carburation the worse they run. And yes I know it is injected and not an electronic carburetor, but it doesn’t have oxygen or other sensors that injected cars have

 

[singinwoodwackr]

Yea, WOT or none, imo, once warmed up.
what size bar?

 

[StihlsawuserMS361]

I do know that about the primer....Should the primer bubble become hard like most anything with similar set up, as the more pumps the stiffer it becomes? (Stihl ultra oil, ethanol free fresh gas)

Dealer told me WOT is ok, which I haven't except briefly when in a log, and then maybe not even full. I don't quite understand your second paragraph?

After the chain started to behave, the saw ran perfect. I always let it idle for a minute or two before shut down. On a restart one or two pulls.

Maybe the runaway chain was caused by an immediate shut down due to being pinched? I'll try 6 pumps tomorrow

Thanks

 

[StihlsawuserMS361]

Yea, WOT or none, imo, once warmed up.
what size bar?

26"

 

[rwoods]

Make sure your decomp is not sticking open when cold. I and at least one other have had that problem.

Ron

 

[huskihl]

I don't quite understand your second paragraph?

Typo on my part. I fixed it.

Don’t run them at half throttle other than for quick limbing jobs. If you’re bucking a log, run it full throttle

 

[PV Hiker]

Typo on my part. I fixed it.

Don’t run them at half throttle other than for quick limbing jobs. If you’re bucking a log, run it full throttle

To add to this... You have a really nice chainsaw one of the top new technologies to be in a chainsaw. You have a different way of breaking in a saw than the norm. I believe you are not doing it any favors by barely using it.

Yes no wide open throttle when there is no load.

Yes partial throttle and blipping when limbing as small limbs don't require load resistance on the motor. But you don't want to do that for very long - some Stihls computers will see that and make it richer then shut down the motor.

My suggestion for you is to warm up the chainsaw to operating temperature for the cylinder, put the bar into some wood and at FULL throttle put some load on it. Work it hard for many cuts. Then let it idle for 20 to 45 seconds and shut it off when you're done.

You are babying the saw and never working it to get the rings seated and heat soaking. You are going to like the chainsaw very much after you break it in, but to get there you are going to have to work it as it is intended.

The bulb just pressurizes the fuel system and returns the waste back to the tank, the bulb will not get hard.

 

[StihlsawuserMS361]

PV and others;
Thanks for your replies and help. Let me clarify a few things.
25" lite bar / chain, not 26".
I've cut several large ash trees, 20" plus in diameter, definitely getting the rpm's up into the power band , not lugging the saw down is my definition of "easy cutting". Probably almost WOT and not realizing. Then I'd idle saw for a few minutes to cool down, then shut off and let cool to ambient and restart next day.
I did try a cold start last night , then this morning, pumping the primer 4x's. Started, stalled,, 1 more pump and ran. Maybe as huskihl mentioned some prime a lot, some not at all. Maybe 8+ is too many for this saw, even though it doesn't actually "prime"?
I do like the extra bar length as compared to my 361 with an 18". Easier on my back. When into a large log, it really runs and throws the chips.
As far as the chain still turning @ idle, hope it's a fluke or hiccup .

 

[Old2stroke]

Still confusion about the function of the "primer". It should be called a purge bulb because that's all it does. It just sucks fuel up the fuel line and into the carb to fill the fuel chamber, removing any air in the fuel supply. Once the carb is filled, the excess fuel is dumped back into the tank. You can pump it as many times as you want but once you can feel fuel being squished through the bulb, more pumping does nothing. The bulb is not meant to pressurize the tank, the amount of fuel sucked out of the tank is the same as the amount of fuel being dumped back into the tank. No pressure difference. The fuel delivery system does not require a pressurized tank and in fact, the pressure that builds up in the tank should never exceed the pop-off pressure of the inlet valve in the carb.

 

[rogue60]

Breaking in a new saw seating rings half throttle = fail

4 tanks without hitting WOT under a good load?

 

[user 122190]

PV and others;
Thanks for your replies and help. Let me clarify a few things.
25" lite bar / chain, not 26".
I've cut several large ash trees, 20" plus in diameter, definitely getting the rpm's up into the power band , not lugging the saw down is my definition of "easy cutting". Probably almost WOT and not realizing. Then I'd idle saw for a few minutes to cool down, then shut off and let cool to ambient and restart next day.
I did try a cold start last night , then this morning, pumping the primer 4x's. Started, stalled,, 1 more pump and ran. Maybe as huskihl mentioned some prime a lot, some not at all. Maybe 8+ is too many for this saw, even though it doesn't actually "prime"?
I do like the extra bar length as compared to my 361 with an 18". Easier on my back. When into a large log, it really runs and throws the chips.
As far as the chain still turning @ idle, hope it's a fluke or hiccup .

When mine was brand new it required some failed attempts to start before finally running. It got better fast. I wouldn't worry about it. Just keep at it. Nothing is wrong. It's just new and needs some time.

 

[user 122190]

BTW, read this. I went thru a few fits with the 500i. All is good now.

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

 

[rwoods]

Still confusion about the function of the "primer". It should be called a purge bulb because that's all it does. It just sucks fuel up the fuel line and into the carb to fill the fuel chamber, removing any air in the fuel supply. Once the carb is filled, the excess fuel is dumped back into the tank. You can pump it as many times as you want but once you can feel fuel being squished through the bulb, more pumping does nothing. The bulb is not meant to pressurize the tank, the amount of fuel sucked out of the tank is the same as the amount of fuel being dumped back into the tank. No pressure difference. The fuel delivery system does not require a pressurized tank and in fact, the pressure that builds up in the tank should never exceed the pop-off pressure of the inlet valve in the carb.

The 500i is fuel injected. On cold starts the bulb must be pushed many times - if I recall the manual correctly - push it 11 times. The warmer the saw the fewer pumps needed. Quite often no pumps on a hot restart.

Ron

 

[PV Hiker]

Since the MS500i is fuel injected and there is no carb bowl to fill, the bulb primes fuel to the injector and adds pressure. How many pushes does it take depends on each saw and temperature,, altitude and when it was last pressurized. Start with 8 pushes and then get to know your saw as to what is best for it and when.

From the Stihl page:
Discover how injection technology works! From preparation for starting, to optimum control of the injected quantity of fuel and timing for ignition by the control unit.

https://e.video-cdn.net/video?video...i&player-id=A66oBW5L1GXFJV5-Tqxofq&width=1280

 

[huskihl]

Still confusion about the function of the "primer". It should be called a purge bulb because that's all it does. It just sucks fuel up the fuel line and into the carb to fill the fuel chamber, removing any air in the fuel supply. Once the carb is filled, the excess fuel is dumped back into the tank. You can pump it as many times as you want but once you can feel fuel being squished through the bulb, more pumping does nothing. The bulb is not meant to pressurize the tank, the amount of fuel sucked out of the tank is the same as the amount of fuel being dumped back into the tank. No pressure difference. The fuel delivery system does not require a pressurized tank and in fact, the pressure that builds up in the tank should never exceed the pop-off pressure of the inlet valve in the carb.

It’s not a purge system on a 500i, as it is on nearly every other piece of o p e. There’s a line from the tank to the bubble and a line from the bubble to the injector. It pressurizes the fuel line to the injector since there is no battery

 

[rwoods]

Manual calls for at least 8 times when cold. Not sure how I got 11 times in my head, mine doesn't seem to care. Though fuel injected, you can flood the saw.

Ron

 

[StihlsawuserMS361]

Montana and others, thanks for the input.
Maybe I'm old fashioned, but when I lay out some considerable dollars for a product, I expect the performance to equal the investment. I justified the saw cost comparing to having it done by a "pro", so that's where I'm at.
I'm familiar with battery -less EFI's in snowmobiles. I may just try to start it tomorrow without pumping. Maybe a couple slow pulls first to charge the fuel pump, then a normal one.Who knows?
I did read into your links and problems early on Montana, thanks. Yesterday, if it had a carburetor, I would have backed off the idle screw. I am liking the 24-25" whatever it's called bar length. For what I'm doing, I don't think I'll ever need longer. I adjusted the oil flow to the factory pin, and it probably uses about 3/4 tank of oil to fuel. I believe Stihl is trying to be EPA friendly, although a DEC agent told me one time (at a car dealership where I worked) oil really isn't a problem, more so antifreeze with the ground water.

 

[Wood Doctor]

Manual calls for at least 8 times when cold. Not sure how I got 11 times in my head, mine doesn't seem to care. Though fuel injected, you can flood the saw.

Ron

That's the same as my MS 441c M-tronic -- pull about 8 times when cold. Eventually it starts but it never lets you know if it's getting close. Its technology is six years older then the 500i, but nowadays we have to realize that "it is what it is".

 

[261cm]

Your 441 sounds like my 261cm. Usually about 7-8 pulls and it starts. It surprised me the other day and fired on 3 or 4 pulls.

That's the same as my MS 441c M-tronic -- pull about 8 times when cold. Eventually it starts but it never lets you know if it's getting close. Its technology is six years older then the 500i, but nowadays we have to realize that "it is what it is".