Skipper Show full post »
ohmslaw
Peddler wrote:
Gap is .010, I use a post card to set the coil over the magnet.


I started using the lid from  box it came in.
Tim
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Crow
single cylinder engine does not get gapped
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Cobranut
Crow wrote:
single cylinder engine does not get gapped


There has to be some gap.  You don't want the magneto rubbing on the flywheel magnets.
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Crow
cobranut i sent you a message explaining
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Peddler
The mag on a single cylinder engine needs to be gaped for certain as the gap effects the timing on breakerless systems.

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Skipper
Sorry this took so long but just received the new coil. Local tech came and we checked fuel while running and cranking. Main line is about 8 and flow at gen regulator to carb is is 7.2. Seems fuel is not a problem. We installed new coil at .010 gap and it would start but barely run rough at very low rpm. Tried different gaps and did not make a difference. Put back old coil it started and ran fine. Checked ohm readings on coils. Original coil was 16400 ohms, new was 10000 ohms. Left old coil in place. Tech is going to see what coils they have in stock and what ohm readings are. This was brand new coil ordered in. We suspect either bad coil or it was packaged in wrong box. I have seen this with auto parts a few times. He will talk to his parts supplier see what can be worked out. Maybe have them ohm a coil before shipping out. 
Thats where we sit so wait and see.
The coil has two mounting bolts that have holes slotted for adjustment but gap does not seem to affect timing. Engine ran the same at 10 - 7 - 14 thousand gap.
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78buckshot
Well that's some bad luck, I haven't had that happen but sure is possible with the low quality parts nowadays. So, fuel sounds good, how about every fitting and hose connection in the fuel system. I had one last week that would start and run as long as the choke was closed, found the rubber manifold was just resting on the throttle body and was sucking enough air that it wouldn't run without the choke.
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Peddler
What is the compression on this unit when cold?
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Peddler
Have you had the demand regulator apart to make sure the treadle valve is in place and working correctly?  It sound like it is flooding with fuel to me.
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Skipper
Right now I have exactly the same setup with old coil. It will start and run fine anytime I want as long as it is no colder than about -10 C. Colder and it will not start just keep cranking. So fuel and connections should be good and are as far as we could check. Oil is checked once every couple weeks and changes regularly. It only has about 60 hrs run time. I doubt there is a problem with compression. I doubt it is flooded cause when below -10 when it does not want to start if I open breather element door and cover opening with my hand I can get it to start. Even then it will run fine. That to me is actually choking system to run rich. I have already checked and the choke plate is working right.
I really believe this is an inherent design fault of these early generac 8kw air cooled units. They start and run and work fine. They just won't start automatically below -10 or - 15 C. They will run fine then if you can get it to start using some tricks.
This unit has done this from the day it was bought and I have had no resolution from original installer.
The issue for me is I bought this to cover a sump pump and we get cold weather often. I can only go away when I know the weather is going to be reasonable.
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Peddler
I will agree that the 8KW units are more problematic than the V twin units and we have always stayed away from them.  Have you taken the air box out and removed the fuel hose and examined the fuel intake area?  I had one that wouldn't start that had a stink bug in that area and was blocking the orifice.  Also maybe try switching the control valve to natural gas to see if this changes the cold starting characteristics. 
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Skipper
Just talked to gen tech they are trying to find right coil for this unit, with the same ohm reading. Both he and I are away till March 5. Will continue then. Thanks will check air box and fuel hose. We have tried switching NG to LP and back made no difference.
Originally it would not start below -10 I added a light bulb as found on your site and now does not start below -15. Is there a problem if I remove the heat shield that is around back side of spark plug and Back over engine head. This would let bulb warm the head intake area better. My concern does the shield direct air flow over head for cooling?
Thanks guys have learned lots from this site.
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Peddler
I'm not following you on the coil issue as far as the ohms.  The correct coil for this unit is an 0G9241T and regardless of the ohms that coil should work.  If the dealer had an older variation of that coil on his shelf then I can see it possible not working as well.  It is very hard to get a good ohm measurement when they are that high temperature alone can have a big impact.  I didn't see where you stated what the compression was on this engine.
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78buckshot
Skipper, do not remove any shroud, the engine needs the correct air flow especially around the head and cylinder. When you get back we can pick it up from where you left off.
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exrace
Peddler wrote:
...I had one that wouldn't start that had a stink bug in that area and was blocking the orifice.

Man...those stink bugs can get into anything!
Nice troubleshooting 🙂 
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Skipper
Sorry have been busy and waiting for right parts. Installed a new coil and engine runs fine. Measured spark on a gap tester and new coil is way better than old one. The new coil is physically much larger than old coil. Maybe they redesigned  coil. Now I have to wait till next winter and cold weather to see of it helps cold starting. This unit only has 138 hrs on it so should last for a while yet. Thanks for all the help I know way more about how these units function because of your assistance. 
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