Dolmar 5100 Problems

[1legwoodchopper]

Let me start by saying thanks in advance. My Dolmar 5100 quit and I am struggling to diagnose. I have been told a tank vent issue and am going to take it to the dealer but they are not close and lack what I would call quality service. So, I thought I would start here.

I pulled it out Friday to do some limbing and small bucking. It started 4th pull after 3 month lay off. Cut for about 20 minutes. Turned it off to clear up the brush pile I had created. About 30 minutes later went to start it and it would not run. Seemed to flood out after just a couple of pulls. Fuel out of the muffler real quick. I pulled the plug to let it evaporate. Put a new plug in just in case. Let is rest 2 hours. Got out the other saw. Tried again and the same thing happened.

I have never touched the carb adjustments since i got it from the dealer. They were on the stops when I looked. Little plastic pieces. One red and one white where turned to where they hit the other adjust ment screw. White over and red under I believe.

Run Stihl oil. 93 octane gas that I bet will have ethanol in it. Can't get much else around here. Could the ethanol eat the seals in the carb, especailly the diaphragm? It's a lot of gas quick but none leaks around at the carb.

I bought the saw new 18 months ago or so. No telling how long they had it. Not a high traffic saw. Dealer support for anything other than Stihl lacks around here.

Any help would be appreciated! Thanks.

 

[MCW]

Not sure if this is the problem or even any help but if I flood my 5100-S it's a real pig. My brother has a habit of squeezing the throttle a heap of times before ever starting a 2 stroke. This always causes problems with my 5100-S. Maybe you have a stuck throttle but I know when or if you have tank vent problems they cause all sorts of problems. My Dolmar 7900 had one with the older style breather and split the tank from pressure build up.

 

[SawTroll]

Flooding doesn't add up with a tank vent issue to me, but I may be missing something?

Did you choke it before attempting to restart it?

 

[blsnelling]

A bad tank vent can cause the saw to starve for fuel, not flood.

 

[huskystihl]

Try setting it to just the run position and set the chain break after you've removed the plug and pulled the rope over about 20 times. Heat the plug up real good and reinstall it and squeeze the throttle wide open and pull it like a madman, if it doesn't eventually fire the carb is gonna need rebuilt. I could be wrong but I don't think 93 octane from shell has ethonal but I could be wrong and probably am.

 

[MCW]

A bad tank vent can cause the saw to starve for fuel, not flood.

Is it a possibility Brad that extra fuel can be forced through the carb if tank pressure goes up while the saw is stopped? I'm not familiar with the inner workings of a chainsaw carby so not even sure if this is possible.

 

[SawTroll]

A bad tank vent can cause the saw to starve for fuel, not flood.

Yes, as it is creating a vacuum, not pressure, in the tank.

 

[blsnelling]

Is it a possibility Brad that extra fuel can be forced through the carb if tank pressure goes up while the saw is stopped? I'm not familiar with the inner workings of a chainsaw carby so not even sure if this is possible.

Yes, and that would be a function of the needle and seat in the carb. It is their function to stop the fuel.

 

[Termite]

huskystihl, here in Indiana Shell 93 octane was 10% ethanol as was Sunoco.

 

[1legwoodchopper]

I got the idea of the clogged vent from another person on here that I PM'd.

I did not re-choke it since it was 90 degrees here.

I did not hit the trigger as it is not necessary with this saw usually.

I was amazed how much fuel and how quickly it came out the muffler.

I will try to start it today when I get home from work. I should be all dried out by now. I will report back.

Thanks,
Jason

 

[blsnelling]

It definately has nothing to do with a bad tank vent. Try this. Drain the fuel from the tank. Pull the spark plug, turn the saw upside down, and somehow pull the engine over until no more fuel comes out. Leave the plug out overnight. Put enough fuel in the saw to run, but not so much that you can't leave the fuel cap slightly cracked. Replace the spark plug, put the saw on fast idle, and see if it'll start. If not, pull the plug to see if it's wet again. If not, put on choke, pull three times, and then move to fast idle. See if that works.

 

[Andyshine77]

My brother has a 510 and he's flooded it just like this a bunch of times, and it was operator error each time. he was getting the orientation of the switch backwards. All the way up is full choke, the center position is run/fast idle, and down is off. Brad explained what to do when you flood a saw to a T. Sorry but I must call operator here.

 

[SawTroll]

My brother has a 510 and he's flooded it just like this a bunch of times, and it was operator error each time. he was getting the orientation of the switch backwards. All the way up is full choke, the center position is run/fast idle, and down is off. Brad explained what to do when you flood a saw to a T. Sorry but a must call operator here.

That may very well be it - I once did the same thing on the 5100S.....

 

[MCW]

My brother has a 510 and he's flooded it just like this a bunch of times, and it was operator error each time. he was getting the orientation of the switch backwards. All the way up is full choke, the center position is run/fast idle, and down is off. Brad explained what to do when you flood a saw to a T. Sorry but a must call operator here.

That may very well be it - I once did the same thing on the 5100S.....

Each time I've had the 5100-S flooded it has been a pig and impossible to restart in the short term, unlike my other saws which seem to be easier to restart after flooding.

 

[indiansprings]

I had one of our wood cutters flood a 361 stihl so dang bad last year it puked fuel. I hadn't ever expierenced a saw flooded so badly, sounds like your 5100.
I didn't think of Brad's method of turning the saw upside down and cranking.
I took an air compressor and blew the cylinder/case out using low pressure so I wouldn't damage any seals. It took four or five attemps to get it dry enough to fire up. Haven't had an issue with it since.

 

[huskystihl]

I had one of our wood cutters flood a 361 stihl so dang bad last year it puked fuel. I hadn't ever expierenced a saw flooded so badly, sounds like your 5100.
I didn't think of Brad's method of turning the saw upside down and cranking.
I took an air compressor and blew the cylinder/case out using low pressure so I wouldn't damage any seals. It took four or five attemps to get it dry enough to fire up. Haven't had an issue with it since.

My 361 did that till it broke in to. We're all guilty of flooding saws from time to time but I wanted to chuck that thing under the bobcat the first month I had it. That was the only saw that, run position, wot wouldn't cure. Once it seated in it never did it again.

 

[J.W Younger]

The first few weeks I had mine I must have fooded it a dozen times. Part of the problem besides me having my head up my ass is the fast idle position barely cracks the throttle.Being use too stihl I would flip the lever up too shut it off and then sometimes down too start, definitly operator error.The quickest way too clear a flood condition if its still minor is pull the air filter and prop the throttle blade open with a pocket screwdriver(dont cut your leg off). If fuels dripping out the muffler more drastic measures are called for.

 

[1legwoodchopper]

Well I tried Brad's way and after 3 pulls I had it flooded again. I am amazed how fast this happens.

It is not operator error as some have suggested. The switch has been in the right spot each time I have tried. I know it is possible to make mistakes but I did not in this case.

I pulled the plug to let it air out and will try again. I am also going to try to clean out the vent that was suggested in the PM. At this point it is worth a shot before I try the dealer.

Thanks again for the help. This is bizzare. I will keep you all informed.

 

[J.W Younger]

Well I tried Brad's way and after 3 pulls I had it flooded again. I am amazed how fast this happens.

It is not operator error as some have suggested. The switch has been in the right spot each time I have tried. I know it is possible to make mistakes but I did not in this case.

I pulled the plug to let it air out and will try again. I am also going to try to clean out the vent that was suggested in the PM. At this point it is worth a shot before I try the dealer.

Thanks again for the help. This is bizzare. I will keep you all informed.

Maybe its trash under your needle valve.If thats what it is then you need too look real close at your fuel line and filter.I had that happen a couple of times with my 460 and it was a soft line swelled to the point the filter was about too fall off.Ethanol no doubt.