My Dolmar 5100 won't run????

[sugarbush]

if you think the problem is in the carb take it back to the dealer , its still under warranty.

 

[astrodon]

if you think the problem is in the carb take it back to the dealer , its still under warranty.

I'm considering that. But if the problem is its gunked up somewhere due to sitting for a couple of mohths with half a tank in it, I don't know that the warranty will cover it. I'll bet it will cost close to the cost of a new carb to pay to have it fixed/cleaned. Does anybody know if cleaning a carb voids the warranty?

Thanks

 

[Justsaws]

Removing screws can void your warranty.

So can Sea Foam.

How friendly is your dealer? Do you think he should warranty a saw that has been messed with by someone who openly admits they do not know what they are doing? I do not think he should.

Stop now if you care about your warranty.

 

[sugarbush]

I'm considering that. But if the problem is its gunked up somewhere due to sitting for a couple of mohths with half a tank in it, I don't know that the warranty will cover it. I'll bet it will cost close to the cost of a new carb to pay to have it fixed/cleaned. Does anybody know if cleaning a carb voids the warranty?

Thanks

sitting for a couple of months with fuel in it isn't your problem.

 

[angelo c]

Just thinking out loud...

lots of us have vacuum/pressure testers. Is there a base line for acceptable Vac for testing a fuel filter/line ? Just thinking if there is a way to isolate the lines/filter so as to test.

Also would it be advisable to just remove the filter for a few runs (after a good tank cleanout) just to isolate the filter from the equation.

PSS whoever suggested blowing "shop air" through the carb might want to add that the air ad better be stepped down considerably as 30 psi is way too high to blast out carbs...IMO

 

[Justsaws]

sitting for a couple of months with fuel in it isn't your problem.

Depends on how old, clean and how it was stored before it got put in the saw that then sat on the shelf for a few months.

Could be nasty stuff stored under the front porch in plastic bottle with no cap.

 

[CHEVYTOWN13]

I better throw in a big stick into the fire...

I recently had a problem with the Zama carb also.

The little bull was on a long cut in some canyon oak when all of a sudden it dropped major rpm's. I pulled off the cut and when I gave it throttle it ran erratically, as if it dropped the H jetting. Other than that, it idled fine and fired on the first pull every time (as I was checking it, thinking I scored a piston)

My guess is that the diaphragm inlet hole was affected somehow and the diaphragm was damaged. I say this because I switched carbs with the 510 and all has been fine since.

The 5100 diaphragm inlet hole is part of the "jet stream" that is going into the carb's throat. It is protected by the black round sponge. If the inlet hole is not affected by the baro pressure (that it needs to function), the diaphragm in the carb will fail and the saw will run rich as the carb is dumping fuel now and not being metered.

On the 6401, the diaphragm inlet hole is not encased. It is out in the open. And I believe there are two and not just one?? I've never had a problem with the 6401 and that has been cutting in dusty conditions(seasoned eucalyptus/oak).

When I get the chance, I'm going to switch the diaphragm (with no cleaning of the carb) to double check my suspicions.

Just my dos pesos...

 

[Woodplayer]

Could be a pinched fuel line. Mine had a similar lean running problem.
http://www.arboristsite.com/showthread.php?t=56856

 

[astrodon]

Well, I pulled the diaphragm off of the carb and everything looks clean and air blows through all of the jets. I'll go and talk to my dealer tomorrow and see what he has to say. I don't expect anyone to fix or pay for my mistakes, but the only thing I did wrong that I can tell is let it sit for 2 months with a half a tank of good fresh mix. After which it ran fine BTW, it was 2 weeks after I ran out the half tank and let it sit dry that I am having problems. I don't think 2 capfuls of sea foam in a full tank or me removing the diaphragm should make Dolmar not responsible for something wrong other than a dirty carb. The only other thing worth noting was that there was a little bit of dust inside the air filter and also in the choke area of the carb. I do keep my filters clean though, and I'm on my second filter after only 10 or so tanks of gas. Once I get this figured out, I'll post back in case the info helps anyone else in the future.

Thanks

 

[mowoodchopper]

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.

Brad Dont know if thats his prob ,but you are correct .
My 5100 can sit for a couple weeks and If I flip it to choke itll flood!
Anymore I just give her a few pulls if it does not hit then I choke it, other wise youll be pulling the plug and clearing it out and start over!

 

[astrodon]

Hey, I just looked up my serial number and my 5100 looks like it is one of the first ones made. The serial number starts with 0512, so I think it was made in December of 2005. I bought it new in May of 2008, and it does not have a prefilter for the top cover or the metal insert for the carb/manifold. Could this be the reason that I am having problems? If I recall correctly, someone said that without the insert the thing sucks air. I would think that sucking air would cause the problem that I am having. Anyone have experience with this particular problem on the older 5100's?

 

[grandpatractor]

Hey, I just looked up my serial number and my 5100 looks like it is one of the first ones made. The serial number starts with 0512, so I think it was made in December of 2005. I bought it new in May of 2008, and it does not have a prefilter for the top cover or the metal insert for the carb/manifold. Could this be the reason that I am having problems? If I recall correctly, someone said that without the insert the thing sucks air. I would think that sucking air would cause the problem that I am having. Anyone have experience with this particular problem on the older 5100's?

That would be an early one alright. I would definitely check to see if it has a ring installed.
It should be the 12th week of 05 when it was made.
Usually they won't idle down when they have problems with the ring not being in there.

 

[Andyshine77]

:agree2:They also tend to rev up or slowdown when you change the saws orientation.

 

[CHEVYTOWN13]

Looks like you found your problem.

I'm going to post this problem nonetheless for future reference in case someone goes thru this problem. The photo's aren't the best. It has a worse kink than it looks. How it got like this, I have no idea.

Here are a couple of photos of the diaphragm assembly.

The diaphragm is kinked. It resembles a cone from a speaker. It should be acting like a speaker cone bouncing up and down with the lever. Because it is kinked, the lever was not making contact with the steel disk (with holes) because the kink caused the steel disk to lift on one side. The lever should be making contact with the steel disk.

<a href="http://s701.photobucket.com/albums/ww11/CHEVYTOWN/?action=view&current=DSCF0687.jpg" target="_blank"><img src="http://i701.photobucket.com/albums/ww11/CHEVYTOWN/DSCF0687.jpg" border="0" alt="Photobucket"></a>

<a href="http://s701.photobucket.com/albums/ww11/CHEVYTOWN/?action=view&current=DSCF0690.jpg" target="_blank"><img src="http://i701.photobucket.com/albums/ww11/CHEVYTOWN/DSCF0690.jpg" border="0" alt="Photobucket"></a>

 

[blsnelling]

The diaphragm is kinked. It resembles a cone from a speaker. It should be acting like a speaker cone bouncing up and down with the lever. Because it is kinked, the lever was not making contact with the steel disk (with holes) because the kink caused the steel disk to lift on one side. The lever should be making contact with the steel disk.

???

 

[Justsaws]

???

:agree2:

 

[Justsaws]

Your symptoms do not sound like an air leak caused by a lack of the metal insert.

The metering diaphragm could be plugged with fine dust between the diaphragm and metal cover. That would be a fairly rare occurrence for most saws.

 

[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

These symptoms are a fairly typical description of a restriction in the fuel systems. You cannot clean the carb without removing it from the saw.

When you sprayed carb cleaner through the carb it worked because of the pressure in the can of cleaner. The saw uses suction/vacuum to pull the fuel through the carb and does not create much suction.

The screen that gets plugged will pass fluid under pressure but not under vacuum. The gaskets that get gummed or stiff are bypassed more or less when you sprayed the fluid from the can.

If on the slim chance you try to use the saw tomorrow and it works you should defiantly get the carb cleaned and new gaskets. If you do not the gaskets could fail at full throttle and you could end up with a lean seized saw. The saw might function because of the effect of the cleaner/Sea Foam on the gaskets. It is not wise to count on that result being long lasting on a 2 cycle engine.

 

[astrodon]

Justsaws, thanks for the insight. I came to the conclusion that the fuel supply is the problem, and that it was probably a gummed up carb. I took it in to the dealer and explained everything I did. I'll wait and see what he says. Just so I know, are you saying the pressure of spraying carb cleaner in the carb could damage it? Or the chemicals in the cleaner do some damage? Also, sea foam in the gas can weaken gaskets? Or pouring pure sea foam in the carb?

Thanks

 

[CHEVYTOWN13]

The metering diaphragm could be plugged with fine dust between the diaphragm and metal cover. That would be a fairly rare occurrence for most saws.

Yes, some fine dust is going to get in for sure, but probably not enough like you said to cause problems. However, in the 5100's case, the inlet hole for the diaphragm metering is encased in a tube that is part of the air filter. I'm assuming, that if the air filter gets clogged, less air is going to impact the diaphragm. I try and clean the air filter after every use. It could be I did not clean the air filter well when this happened, thus leading to the kinked diaphragm.

Astro, it's too bad you didn't try fixing this yourself. It sounds like you are mechanically inclined. But I do understand dealer support, especially if it's free.