Dolmar 5105 starting issues

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BushWackin

ArboristSite Lurker
Joined
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Location
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Hi guys,

I am having an issue with a dolmar 5105 that I purchased from a gentleman on this site a couple years ago.

Easy start, fully adjustable carb, 5100s muffler to keep heat down, a tach to check rpms. About 25 hours on it since I got it. Not much use in it before I got it.

I have run the saw regularly including yesterday for two hours or so.

Fueled it up, put on a fresh chain, lube, all good this morning and cut up some brush for 30 or so minutes and it stopped running on its own. No hard use, 4 inch or smaller brush.

I was concerned I may have burnt up the saw, but I have a tachometer on it so I know I have been keeping it in the slightly rich side.

I pulled the plug and muffler to make sure the Piston, ring, and cylinder looked good. The Piston still has about 50 percent of it's original machine marks, no visible scoring that I could tell. Some carbon buildup in the very bottom of the skirt and on the top of the Piston and in the exhaust Port. Nothing crazy best I can tell.

The spark plugs was wet and a darker brown. Definitely not a lean gray or black so I cleaned it up just in case.

There was quite a bit of gas in the exhaust so I dried it out, let the cylinder dry out, cleaned the plug, and put it back together. I pulled the air filter, which is clean, put in a little seafoam and let it sit.

Tried getting it to start, but nothing on choke or idle. Won't even kick once.

I thought maybe my carb settings were bad after tweaking them a couple times so I screwed all three carb settings in till lightly snug and backed them out 1.5 turns each . Still nothing, tried 1 turn high and low, still nothing.

Tried a different plug, still nothing.

Waiting a while to see if I flooded it, and nothing.

This saw had up until today started after 2-3 easy start pulls on choke, and 1 or 2 pulls after the pop.

The gas is ethanol free, 89 octane at 42:1 with amsoil saber. Mixed a few months ago, but stored well and have bad no issues with it until today.

Any ideas? No spark? Do I have the wrong carb settings for dolmar? Including the idle screw?
 
Take out the the plug and insert a teaspoon of fuel in the cylinder. Replace the plug and see if she pops and tries to run after a pull or two. If not, then you likely have an electrical problem and no spark is firing. Ignition module may be gone. If it starts to run and then stops, you might have a fuel flow or carb problem. However, if the plug is getting wet with fuel as you say above, then that's not likely.

You can also check for a spark by removing the plug, fasten it to its connector, connect a jumper between the plug's threads and the cylinder. Pull with ignition on and see if she sparks. The more I read your post, the more I think the trouble is electrical. You may even have a bad switch or a ground out somewhere.
 
I just checked for spark, and I don't get anything.

I didn't use a jumper, but I grounded the plug on the cylinder, and I also help the plug in my hand and grounded my hand to the cylinder and didn't get shocked.

The saw was in the on position, and it is getting fuel, my wife confirmed this as it if stinking up the living room. .

This is all new territory to me, I will have to look up how to diagnose further.

Thanks for the input .
 
Wi
BushWackin said:
I just checked for spark, and I don't get anything.

I didn't use a jumper, but I grounded the plug on the cylinder, and I also help the plug in my hand and grounded my hand to the cylinder and didn't get shocked. The saw was in the on position, and it is getting fuel, my wife confirmed this as it if stinking up the living room. This is all new territory to me, I will have to look up how to diagnose further.

Thanks for the input .
Click to expand...
I figured as much. With no spark, the saw will not run under any circumstances. What you must do next is determine why there is no spark. It could be a wire grounded out, bad connection, a bad switch, or the ignition module stopped working. Electrical engineering is now involved.

I have run into modules that were shorted out or developed a bad gap, so perhaps you should start by removing the crank housing, clean it all around, and check the IM. The gap should be about 0.01" at the time it sends juice to the spark. Check all the wires and connections first. Look for anything that could cause problems with the circuit.

Horror story: A Stihl mechanic last year disconnected a wire to the IM on an MS362 and said to the owner that he would fix the saw for $450. The owner gave the saw to me to examine for a second opinion. I reconnected the wire. The saw started and ran immediately.
 
cuinrearview said:
I haven't read of a coil failure on these, but this sounds pretty textbook.
Click to expand...
It may not be a coil failure. It could be just junk shorting it out. I ran into this a few years ago on a Stihl 046 Mag. It had so much damp junk packed across the terminals that it produced a short circuit. The pull cord housing can pick up crap like a vacuum cleaner and that includes insect nests. About anything can get in there. One time I even found mud dobbers and lots of eggs.
 
cuinrearview said:
I haven't read of a coil failure on these, but this sounds pretty textbook.
Click to expand...

I found a couple posts on here about them failing, but not many. When I get some time next weekend I will do my best to check all the connections and the switch before buying a new coil.

$70 or so isn't to bad, but on a $250-300 saw it sure seems like a lot.

Hopefully I find a bad switch or connection.

Thanks for the replies, both of you.
 
If you get to the point that you've ruled everything else out and are suspecting the coil i could pull the coil and flywheel off of mine depending on where you're at in IN. I'm down near the border quite often.
 
Thanks for the offer! That's very kind of you.

I am down in the southern part of the state, Bloomington, so it would probably be cheaper to just buy the part than to drive up.

Though, I very much appreciate the offer.

I hope the Doc is onto something, and that I just need to give her a cleaning and maybe some tightening.

I will let you guys know what I find.
 
Well, I finally got back to diagnose.

I cleaned both my spark plugs. I then disconnected the starter switch, slid the connector off and made sure it wasn't touching, and nothing when I pulled the cord.

I pulled the clutch cover and blew everything out, and wiped it down. Not all that dirty. I checked all the bolts on the ground and the coil. None were loose. Checked for spark again, and I do not see anything.

Pulled the coil and cleaned it up, and lightly sanded all contacts and cleaned them. Made sure the ground connection was good and tight. Reinstalled the parts and tried spark again, and nothing. I also moved around the wires inside the outer covering on the coil a little bit just in case they were shorting out under the cover. Nothing.

I feel like I am down to a bad coil.

I tried taking some photos but not my phone won't take any.
 
disconnect the wire from the spade terminal on the coil, pull over and check for spark. no spark=bad coil.

what color coil and sleeve on the coil wire?
 
I just checked that too.

I get no spark with either spark plugs.

It is a black coil with a black sleeve on most of the wire, and a sliding green sleeve up near the plug boot.

Unless my lack of chainsaw knowledge is getting in the way, it looks like a coil.

It seems this is very unusual, especially with a low hour saw like this .
 
F150, is 181143211 the right part number?

It looks like 2010 214495 may be my serial number.

It is an easy start 5105.
 
fordf150 said:
disconnect the wire from the spade terminal on the coil, pull over and check for spark. no spark=bad coil.

what color coil and sleeve on the coil wire?
Click to expand...

Agreed. You have to isolate the kill switch. If you remove the wire to the kill switch and still don't have spark, then it has to be the coil. If you have spark after disconnecting the kill switch wire, then wiring is the issue.
 
AlfA01, thanks for the input.

I tried to get some spark by isolating the kill switch. I tried three different ways, and I couldn't see any space with either of them.

1) Disconnected the wire at the coil like ford f150 mentioned.
2) Disconnected the wire at the ground screw.
3) disconnected the connector on the switch.

None of these showed any visible spark that I could tell. Nor did it shock me when I held the cylinder and plug in my hand while pulling the cord.

I hope my diagnosis methods were accurate, and that the coil fixes it.... If not, back to the beginning.

I a sure @fordf150 will be able to provide the parts.
 

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