Help diagnosing MS500I

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Go to a properly trained STIHL technician and let him do it. Without the proper knowledge things can be messed up fast and easy.
With today's society, properly trained people have already moved on, and are already working in another field.
People don't stay at one job long enough to get good at anything.

Dang... I must be getting old......
 
Sorry to sound like a broken record but basics first. Test spark with an ignition tester with a large gap, not just a sparkplug. Make sure fuel is flowing freely and keeps flowing. Compression via handle. Pop the muffler and look. Go to have air also. OMG it's got fuel injection!!!!!.
Don't bypass the normal stuff. It will get you every time.
I would suggest a visual inline spark tester when runni ng to see if it shuts down before it quits.
 
I swear by Fuel Fit. I put the dose in the fuel can when I fill up. I've never had a fuel problem since I started using it. Mowers, saws and strimmers start easy every time, even after sitting over winter.

https://www.briggsandstratton.com/eu/en_gb/products/care-products/fuel-fit.html

View attachment 1005972
I'm not talking fuel longevity, I'm talking about fuel that won't even light when you pour some out on the concrete. Lol
 
The reason I don't think it is a filter is because it will rev up just fine if you are quick enough to get your finger on the throttle. It's too big a saw for me to drop start it with my finger on the throttle, and I don't even know if they will start that way.
I will take that filter out and clean or replace just the same.
I'll have to find out about the special cable as well.

I'll reply if or when I get it going and let everybody know.
If a reset doesn't clear up the issue, and it smokes a bit more than it should, it's probably the injector "dribbling" fuel into the crankcase after shut off, or even while running.
That would mean the injector needs replaced.
I know my encounters are with the TS500i; but it is the same technology.
When a customer replaces a really clogged air filter, or uses a different type of fuel, a reset may be necessary.
It's been really hot here recently, and most saws will develop enough pressure to ooze fuel out of the tank vent, which can wet the air filter with fuel, causing an imbalance in the fuel to air mixture that the computer just can't "tune it out".
 
The saw will start and idle for a couple of seconds and cut off. If you are quick getting to the throttle it will rev up and sounds normal, like you could cut with it normal, but if you drop back to idle it will run maybe 5 seconds and cut off. I thought it might be the fuel pump, so I replaced that as well as the hoses. Same thing.
I have not run a diagnostic on it, have the software, but I know on the other models they don't tell you much if they aren't running.
Compression is good.
Any ideas ?
My 500i tends to stall after 2-3 seconds when cold, but not when it is warmed up. The dealer could not find anything wrong.
 
I think were going to see many instances of wood pulp from ingress into the fuel tank clogging filters and the injector proper too.

Injectors have some pretty fine tolerances, I do see the need for the 3 filters, and yet I think over time were going to see more injector issues as wood pulp is different to the dust from the concrete saws that have run this system for much longer.
Only the finest filter matters. It will remove anything that passes the coarser filters. If they are all the same pore size, it is a waste of space.
 
If a reset doesn't clear up the issue, and it smokes a bit more than it should, it's probably the injector "dribbling" fuel into the crankcase after shut off, or even while running.
That would mean the injector needs replaced.
I know my encounters are with the TS500i; but it is the same technology.
When a customer replaces a really clogged air filter, or uses a different type of fuel, a reset may be necessary.
It's been really hot here recently, and most saws will develop enough pressure to ooze fuel out of the tank vent, which can wet the air filter with fuel, causing an imbalance in the fuel to air mixture that the computer just can't "tune it out".

I ordered the cable today. As luck would have it the item is not in stock, not in Hillsborough anyway. I'm sure it will show up from somewhere eventually.

In the meantime we got another MS500I in that had a tree dropped on it. One bar stud is bent , the other is broken off even with the crankcase. The chain brake is broken. Who knows what else. May be one of those gifts that keeps on giving. Not many Stihl dealers that would deal with that. But, we will. Or, I will I should say.

Anyhow, I'll let everybody know what the diagnostic says when the cable comes in. Be interesting to see.
 
Did they do a reset on the MDG-1 ?
There is a tiny screen under where the supply fuel barb goes into the injector. They can get plugged up, but rare.
It can be pulled with pliers easily by wiggling back and forth. Getting the screen out is a job for a paperclip.
I personally don't see the need for three screens. (Fuel pickup, screen in the fuel pump, and one screen in the injector.
Hey Alexcagle, wondering where I find the screen. I bought used TS500i. Seller was able to start it normally. I couldn't, nor could my mechanic buddy. Took apart and flywheel and stator were worn so we replaced. Mechanic says this has a lot of use and abuse on it. The throttle trigger won't lock for cold start it is so worn. Replaced kill switch and got spark but still tough to start. Replaced plug and fuel filter. Pretty sure it is a fuel delivery issue as plug seems dry after lots of priming and many pulls. Not sure what the spring loaded primer is supposed to feel like but it doesn't have the feel of a normal primer bulb. Once it starts it screams and sounds perfect. Try to re-start after making a couple cuts and same problem. So if it runs good once started, can this be an injector issue causing the near impossible start? trying to start this is tougher than a gym workout. :rolleyes:
 
Hey Alexcagle, wondering where I find the screen. I bought used TS500i. Seller was able to start it normally. I couldn't, nor could my mechanic buddy. Took apart and flywheel and stator were worn so we replaced. Mechanic says this has a lot of use and abuse on it. The throttle trigger won't lock for cold start it is so worn. Replaced kill switch and got spark but still tough to start. Replaced plug and fuel filter. Pretty sure it is a fuel delivery issue as plug seems dry after lots of priming and many pulls. Not sure what the spring loaded primer is supposed to feel like but it doesn't have the feel of a normal primer bulb. Once it starts it screams and sounds perfect. Try to re-start after making a couple cuts and same problem. So if it runs good once started, can this be an injector issue causing the near impossible start? trying to start this is tougher than a gym workout. :rolleyes:
Are you holding the throttle open when starting cold?
 
yes, holding wide open, as if the throttle lock mechanism worked. In this case, it's my toe arched up. :D
 
yes, holding wide open, as if the throttle lock mechanism worked. In this case, it's my toe arched up. :D
Well my brand new one wouldn't start either tll I didnt touch the throttle,leave that alone, I think thats the proper way! Try it and get back to me. Just prime it , no decompression, no throttle and pull.
 
Sorry for not adding any resolution to this thread.
I got the 500I with the broken and bent studs back in good shape.
As far as the one with the running issue, the diagnostic program did not identify any problem.
I brought the saw home hoping to put it in some wood, but I never could get it running long enough. The saw has seen a lot of use, clutch sounds like a rattle trap.
Anyhow, I have pulled on it all I am going to.
 
Sorry for not adding any resolution to this thread.
I got the 500I with the broken and bent studs back in good shape.
As far as the one with the running issue, the diagnostic program did not identify any problem.
I brought the saw home hoping to put it in some wood, but I never could get it running long enough. The saw has seen a lot of use, clutch sounds like a rattle trap.
Anyhow, I have pulled on it all I am going to.
That's a shame your not pulling it anymore.
Tools can be a pita.
I digress :)

Change the spark plug
GL
 
That's a shame your not pulling it anymore.
Tools can be a pita.
I digress :)

Change the spark plug
GL


It's not unusual for me to go through 20 pieces of equipment a day working two days a week at the Stihl dealer. Sometimes more. It's also not unusual to pull on a piece of equipment that you know is flooded 20 or 30 times holding it wide open. Luckily they are usually two cycle weed eaters and blowers and not MS880's.

In the meantime, you can pull to your heart's content.
 
It's not unusual for me to go through 20 pieces of equipment a day working two days a week at the Stihl dealer. Sometimes more. It's also not unusual to pull on a piece of equipment that you know is flooded 20 or 30 times holding it wide open. Luckily they are usually two cycle weed eaters and blowers and not MS880's.

In the meantime, you can pull to your heart's content.
Do you remove the air filter when doing that?
 

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