Stihl ms500i flooding issue

[CRudy]

I got a 500i I run primarily at work. Lately, half of the time I grab the saw out of the truck after sitting all night or all weekend, the pull cord is locked up and I cant turn the saw over at all. Pull the spark plug out,fuel doesnt drip out of the cylinder, it pours out of the cylinder. Muffler and air filter also almost filled with fuel? I cant pull the starter rope because the cylinder and crankcase are full of fuel... Any idea why the saw would do this? Is it leaking in the cylinder somehow from hitting bumps going down the road? Never had a problem like this for 3 years of owning the saw until now. Let me know your thoughts. Thanks

 

[ballisticdoughnut]

I would suspect a leaking fuel injector. I’ll look at the service manual tomorrow at work for the proper test procedure.

 

[CRudy]

Ok cool thanks

 

[alexcagle]

Yes, +1 here on the injector.
They do wear over time.
Just like throttle shafts on a carburetor do.

 

[ballisticdoughnut]

Yes, +1 here on the injector.
They do wear over time.
Just like throttle shafts on a carburetor do.

Replaced an injector on a TS500i not long ago. Was a not start condition.

 

[buzz sawyer]

Does the saw still depend on an impulse to pressurize the fuel? Maybe the tank vent is plugged?

 

[Twinfield]

When replacing the injector, make sure to remove the small cone shaped plastic piece inside the hole where it goes into. You should see one on the new injector.

 

[ballisticdoughnut]

Ok cool thanks

Of course I get to work this morning and our internet is down. I’ll keep checking. I have a 500i here for a new top end (snagged a ring) so I can post some pictures of the injector. Testing it is pretty simple, getting to it not so much.

 

[ballisticdoughnut]

On the 500i you’ll wanna pressure test the injector on the fuel in side, block off the return which is to the lower left of the inlet. Since it sounds like your flooding issue is intermittent you may not detect a problem first time around. I would say seven to ten PSI is a reasonable test pressure considering running pressure is likely less than that. I still haven’t been able to access the service manual due to our internet being down at work. I’ll update if I discover any new information.

 

[CRudy]

Hey everyone thanks for the information, and thanks for the pics ballisticdoughnut! I'll have to wait for a rainy day in order to tear the saw apart and check the injector I reckon. in the meantime ill get an injector priced out and get a buyer lined up for the kidney Ill have to sell to afford it lol. I'll let yall know what happens. thanks again

 

[DND 9000]

Go to your dealer. A properly trained and equipped repair shop has to do it. You can`t do it by yourself.

 

[CRudy]

Still haven’t gotten a rainy day to tear the saw apart yet. Replacing the injector wouldn’t be just unbolting it and sticking a new one on, sort of like replacing a carburetor? I’ve never messed with injectors before so I’m just curious what the repair shop has to do that requires certain tools or training

 

[ballisticdoughnut]

The injector is kind of a pain to replace. Tank needs to be removed, few hoses and wiring harnesses need be disconnected. Once your there actually removing the injector is kind of a delicate process, if you ham fist it things will break.

 

[CRudy]

Hey sorry its been a while, just too busy to make it a priority to tear down lol. So I got it all taken apart and took the injetor out and it was leaking down on the pressure test fairly quickly. Granted I was doing the pressure test with the injector in the "injector module" but the whole thing wasnt attached to the cylinder but it still should work I would think.

Now with that being said, I have a new injector being ordered(Just the injector and O rings and stuff, Not the whole injector module that it mounts into). Sucker is about 300 bucks... but anyways is there anything in particular i need to do when putting this thing back in? Grease the o-rings? Do some sort of recalibration if-and-after i get it back together alright? That thing is pretty deep in the weeds on that saw so i dont wanna have to tear it apart again or mess up and expensive part lol. Thanks a lot

 

[CRudy]

Oh also any idea what the circular vent looking thing is just behind and to the left of the fuel intake barb is on the fuel module? it almost looks like you can twist and remove it but idk.