My Dolmar 5100 won't run????

[astrodon]

About 10 tanks through her, just used her 3 weeks ago and she ran fine then. I switched from 87 to 89 octane and made up some fresh mix which my other saws run fine on with very minor adjustments. Today, she starts and idles fine but when I hit the throttle she screams for 5 or 10 seconds then dies. WTF??? I put her away dry 3 weeks ago, and she sat for 2 months with half a tank in her before that, so I think the carb must have gotten plugged or something, but why does she run fine for 5 or 10 seconds (sometimes longer) if the jets are plugged?

My local dealer said if I brought it in, it would take until the end of the week, and I'd really like to get her fired up before then. Any ideas on how to clean a hopefully not too gunked up carb?

Thanks

 

[nate cutter]

pull the air filter off and see if the is any dust past the filter but it could be a air leak or a gas tank vent plugged up

 

[blsnelling]

Neither a tank vent or an small air leak is likely to prevent a saw from firing up. I'd guess that you have the saw flooded. It's VERY common on that model from what I hear.

 

[Justsaws]

About 10 tanks through her, just used her 3 weeks ago and she ran fine then. I switched from 87 to 89 octane and made up some fresh mix which my other saws run fine on with very minor adjustments. Today, she starts and idles fine but when I hit the throttle she screams for 5 or 10 seconds then dies. WTF??? I put her away dry 3 weeks ago, and she sat for 2 months with half a tank in her before that, so I think the carb must have gotten plugged or something, but why does she run fine for 5 or 10 seconds (sometimes longer) if the jets are plugged?

My local dealer said if I brought it in, it would take until the end of the week, and I'd really like to get her fired up before then. Any ideas on how to clean a hopefully not too gunked up carb?

Thanks

If all you did was switch octane and try and start a saw that has been sitting then you should start where the fuel goes. If the saw you have can be started like normal, repeatable but is not able to be rev-ed up with out dying here is where I would start.

Gas tank
Fuel Filter
Fuel line
Carb
Tank vent

Did you re-tune it? If so take it back where it was.

Is the plug dry?

When you say "scream", do you mean runs like normal or faster than you remember.

Two months with crappy mix, the right weather and certain storage conditions can gum up a filter, carb and vent.

If it is screaming and falling off until it dies while you are holding the throttle open you should repair it before trying to use it as that can damage the engine.

 

[astrodon]

pull the air filter off and see if the is any dust past the filter but it could be a air leak or a gas tank vent plugged up

There is a little bit of dust past the air filter, not much and I wiped it out and sprayed the whole thing with carb cleaner. Would dust in the carb do this?

Neither a tank vent or an small air leak is likely to prevent a saw from firing up. I'd guess that you have the saw flooded. It's VERY common on that model from what I hear.

She fires just fine, but doesn't like to be throttled up..... just dies.

 

[THALL10326]

About 10 tanks through her, just used her 3 weeks ago and she ran fine then. I switched from 87 to 89 octane and made up some fresh mix which my other saws run fine on with very minor adjustments. Today, she starts and idles fine but when I hit the throttle she screams for 5 or 10 seconds then dies. WTF??? I put her away dry 3 weeks ago, and she sat for 2 months with half a tank in her before that, so I think the carb must have gotten plugged or something, but why does she run fine for 5 or 10 seconds (sometimes longer) if the jets are plugged?

My local dealer said if I brought it in, it would take until the end of the week, and I'd really like to get her fired up before then. Any ideas on how to clean a hopefully not too gunked up carb?

Thanks

A 5 second scream is usually a saw that starts on choke, being forced fed fuel by way of the choke itself. Take the choke off she screams and dies. That's a saw getting no fuel..

 

[astrodon]

If all you did was switch octane and try and start a saw that has been sitting then you should start where the fuel goes. If the saw you have can be started like normal, repeatable but is not able to be rev-ed up with out dying here is where I would start.

Gas tank
Fuel Filter
Fuel line
Carb
Tank vent

Did you re-tune it? If so take it back where it was.

Is the plug dry?

When you say "scream", do you mean runs like normal or faster than you remember.

Two months with crappy mix, the right weather and certain storage conditions can gum up a filter, carb and vent.

If it is screaming and falling off until it dies while you are holding the throttle open you should repair it before trying to use it as that can damage the engine.

Screaming as in running normal. In the few seconds I have, i can get get it revved up with a slight 4 stroke. Sounds normal to me, until it just bogs down and dies. One pull and she fires right back up and idles. I tried adjusting the H side but to no avail and put it back to where it was. Is the tank vent in the cap? If so I will try running it on its side with the the cap cracked open slightly to test it. A fuel filter would need to replaced I would think. What about a fuel line? Can that be cleaned?

Thanks for all the help and suggestions I usually take good care of my equipment and have never had a problem with bad fuel screwing things up, so I kind of a newb to troubleshooting this.

 

[TDunk]

Correct me if i'm wrong, but think those carbs. have something in them that gets plugged up and causes them to run funny. You need to disassemble the and blow shop air through all the holes. Do a search for "Dolmar carb probs." or something similar and put on your reading glasses, it's on this site somewhere.

 

[theoctagon]

i had roughly this same problem on a little stihl i worked on. The exhaust screen was plugged. I took it out burned it off with a bottle torch and installed it. Ran great after that.

 

[BarkBuster20]

Correct me if i'm wrong, but think those carbs. have something in them that gets plugged up and causes them to run funny. You need to disassemble the and blow shop air through all the holes. Do a search for "Dolmar carb probs." or something similar and put on your reading glasses, it's on this site somewhere.

not nit picking but i figured this would be a good oppurtunity to bring this up. It seems like here on AS it is often said "go look through old threads or such" well sometimes its to time consuming and turns into a "nvm" type of deal. im sure just about everything has been talked about on here, but sometimes its just easier to ask again about certain stuff, instead of sifting through a 100 threads. not to mention it gives us something to talk about.

 

[TDunk]

not nit picking but i figured this would be a good oppurtunity to bring this up. It seems like here on AS it is often said "go look through old threads or such" well sometimes its to time consuming and turns into a "nvm" type of deal. im sure just about everything has been talked about on here, but sometimes its just easier to ask again about certain stuff, instead of sifting through a 100 threads. not to mention it gives us something to talk about.

I understand, but i wasn't 100% sure on the cause/cure and that's why i had mentioned looking it up. (didn't want to steer him in the wrong direction) Plus i knew the thread couldn't be more than a month or two old.

 

[BarkBuster20]

I understand, but i wasn't 100% sure on the cause/cure and that's why i had mentioned looking it up. (didn't want to steer him in the wrong direction) Plus i knew the thread couldn't be more than a month or two old.

yeah, i wasnt even directing it towards you or this thread, kinda just saw it as a good oppurtunity to bring it up.

 

[Scooterbum]

About 10 tanks through her, just used her 3 weeks ago and she ran fine then. I switched from 87 to 89 octane and made up some fresh mix which my other saws run fine on with very minor adjustments. Today, she starts and idles fine but when I hit the throttle she screams for 5 or 10 seconds then dies. WTF??? I put her away dry 3 weeks ago, and she sat for 2 months with half a tank in her before that, so I think the carb must have gotten plugged or something, but why does she run fine for 5 or 10 seconds (sometimes longer) if the jets are plugged?

My local dealer said if I brought it in, it would take until the end of the week, and I'd really like to get her fired up before then. Any ideas on how to clean a hopefully not too gunked up carb?

Thanks

You have other saws? If it's under warranty take it to the dealer and be patient.If not pull the carb and give it a thorough cleaning.

How old is this saw?

 

[motoroilmccall]

Sounds like a busted fuel line. Its cheap, just replace it. I've had more headaches over fuel lines than I care to admit. You look at it with a flashlight and everything and it looks fine, but until you stretch it a little you can't tell if its good or bad. I had a line that split right down the mold line (obviously a manufacturing defect, but whatever), me and 2 saw mechanics tore the thing apart and finally found the crack... Just goes to show even guys who've been doing it for 20 years let one slip by now and then.

 

[BarkBuster20]

a friend of mine came by and said local stihl dealer, is now carrying dolmar

 

[Justsaws]

Screaming as in running normal. In the few seconds I have, i can get get it revved up with a slight 4 stroke. Sounds normal to me, until it just bogs down and dies. One pull and she fires right back up and idles. I tried adjusting the H side but to no avail and put it back to where it was. Is the tank vent in the cap? If so I will try running it on its side with the the cap cracked open slightly to test it. A fuel filter would need to replaced I would think. What about a fuel line? Can that be cleaned?

Thanks for all the help and suggestions I usually take good care of my equipment and have never had a problem with bad fuel screwing things up, so I kind of a newb to troubleshooting this.

If it is a tank vent issue usually the symptoms will get worse each time you start the saw repeatably. The saw will not run as long and get harder to start.

Usually letting it sit or cracking open the gas cap will alleviate the symptom until a vacuum is pulled again, the saw is started. Dolmar updated the foam filter for those saws tank vents according to the search I just did.

If the saw symptoms do not get worse each time the saw was started then it is probably the fuel filter and carb screen. Replace the filter and clean out the carb screen and the carb body.

 

[SawTroll]

Start with the simplest - changing the fuel filter just solved a similar problem on my 353.

 

[huskystihl]

Start with the simplest - changing the fuel filter just solved a similar problem on my 353.

I agree! Sonds like fuel filter but none the less a saw that new is a dealer issue and should be handled as such. I found that with my stihls if theres gonna be a problem that they pop up right away. I had a 192 and 270 that had some goofy carb issues that were noticed the first hour they were in use, luckily I have a good dealer and he just simply switched out the carbs knowing these are production saws. Problem fixed.

 

[grandpatractor]

A 5 second scream is usually a saw that starts on choke, being forced fed fuel by way of the choke itself. Take the choke off she screams and dies. That's a saw getting no fuel..

:agree2:
Either a cracked fuel line or junk in the carb. More likely some waxy buildup from sitting.

 

[astrodon]

Thanks for all of the tips! I forget who asked, but the saw was purchased new in May 2008. I pulled the fuel filter and sprayed some carb/choke cleaner through it backwards and lots of it came easily right out of the filter. I also crimped my fingers around the fuel line with the red nozzle inside of it (where the filter came off) and sprayed there. I could see some of it coming out of the carb and none of it coming out of the fuel line between the carb and tank. That probably doesn't really prove anything about the fuel line.

I sprayed cleaner in the carb and I put some sea foam in the gas in the full tank and fired her up. It took 10 or 15 pulls to get enough of the cleaner out of the carb and it sputtered/smoked/died a few times while the pure gas made its way in. This makes me think that the fuel supply to the carb is not the problem, as the tank was drained and dry and the whole carb full of cleaner before I filled it up and started pulling the rope. I did get it to idle and revved it slightly, not even half throttle. Lots of smoke from the cleaner/sea foam and I could feel the exhaust easily on my hand a foot or two from the muffler. I don't think the muffler is plugged.

I drained the tank again and put fresh mix with no cleaner in it and it runs worse. This was all last nigh before I went to bed. I eventually flooded it, so I let it sit all night and will be trying again this afternoon. If it doesn't fire up and run normally, I'm pulling the carb and taking it apart. I'll test the fuel line by pressurizing it slightly and I'll clean whatever I find inside the carb. I've never done this before, but I can't stand not knowing how to fix my own stuff. A new carb is only $60. If I have to ruin a carb to figure it out, oh well

Wish me luck!