# Yamaha ef1000is Generator Help



## Homer6679 (Oct 29, 2022)

Picked it up of marketplace, the guy said there was something wrong with the recoil starter. Well the recoil works fine but I can get this thing to even pop. Here is what I’ve checked/confirmed is good so far:

Kill switch
Magneto
Spark plug
Tank vent 
Fuel pump
Carb
Fresh Fuel
Exhaust arrestor
Compression (135psi with a drill)
Valves are not stuck
Timing is correct (both camshaft and flywheel pin)
Low oil switch

What am I missing?

Also if this thread needs to be moved please let me know.


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## Lionsfan (Oct 29, 2022)

Will it fire if you give it a little puff of ether?


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## Homer6679 (Oct 29, 2022)

Nope, spark plug is wet after trying to start it with a drill on the flywheel


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## nedsim (Oct 29, 2022)

I just uploaded the service manuals for the generator to your inbox. Let me know if I didn't do it right and you don't get them.

I owned one of these for a while. The carburetor was very fussy. Tiny jet and very prone to gelling ethanol gas -- much worse than anything else I've run across.


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## davidprivett (Oct 30, 2022)

yes these carbs are fussy but are you sure you are getting a good spark? I had a chonda (Predator) engine and it had the low oil switch and the module that goes between the mag. and the oil switch to ground went bad, killed spark , so I would suggest disconnecting that circuit form mag. to test ing. system. and while you are at it I have seen dirt dobbers build nests on magnet on flywheel when you turn over flywheel scrapes off mud but leaves film the prevents good action between mag. and magnets so weak spark. good luck but should be kinda easy to figure out.


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## Homer6679 (Oct 30, 2022)

I grounded the plug to the crankcase and saw a bright white spark. I assumed it was good, pulled the coil and primary resistance was way out of spec. My question now is, why did I see spark but the resistance was out of spec?


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## davidprivett (Oct 30, 2022)

as far as I know they say the spark should be blue , i have seen spark the was not good be kinda yellow , i know this you have to be quick to see it anyway expecially when you are trying to rope start it any hold the plug and look at it at the same time, lets face it we were born with to few hands.


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## thenne1713 (Dec 8, 2022)

Homer6679 said:


> Picked it up of marketplace, the guy said there was something wrong with the recoil starter. Well the recoil works fine but I can get this thing to even pop. Here is what I’ve checked/confirmed is good so far:
> 
> Kill switch
> Magneto
> ...


SPARK?? Can just be a bad Magneto? Or if flywheel has been removed by previous owner/tech, Key maybe Off/ out of time? Is it magneto, or does it have Points/ Condenser?


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## Homer6679 (Dec 8, 2022)

thenne1713 said:


> SPARK??


Did you read the entire thread?


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## thenne1713 (Dec 10, 2022)

Homer6679 said:


> Did you read the entire thread?


I did read the full thread, but a wet plug says NO SPARK, or BAD FUEL. (I CAN TELL 3-4 FUEL TALES OF Fresh Fuel mistakes by family/ neighbors, and fuel damage in just 3-4-months). Spark can b Magneto, plug, kill switch. Had a PW that vibration/ sheetmetal edge had rubbed thru kill switch insulation causing Intermittent. Go back thru the basics, drain and try diff fuel source? Opposite side of coin is FLOODING? Good Luck


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## Homer6679 (Dec 10, 2022)

If you read the thread then you would know that I checked all the basics and eventually found that the coil’s primary resistance was out of spec. My question is why did I see spark but the coil’s resistance is way off?


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## Smitty Smithsonite (Dec 11, 2022)

Resistance is a terrible troubleshooting measurement. Reason being, is it's static. You want dynamic tests. Sure, if it's open, then a resistance check will tell you that, but 99% of the time, it's somewhere in between. 

You would want known good current specs and compare them to what you had. You probably had spark in atmospheric pressure, but add 135 PSI to atmospheric, and now you need another 10kV (a guess) to jump the gap ... which the coil couldn't produce. In other words, spark outside, but no spark in the combustion chamber where you can't see.


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## Homer6679 (Dec 12, 2022)

I compared to it to the service manual spec and it was super high. Thanks for your input, how do you test coils then if resistance is a bad test?


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## Smitty Smithsonite (Dec 12, 2022)

Current draw through the coil in Amps. That's not a spec you'd find anywhere, so you'd have to test a known good, or find someone who has to get that information. If that's not possible it becomes just process of elimination. Otherwise known as firing the parts cannon and hoping for the best. Spray and pray!


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## mbrick (Dec 12, 2022)

If the plug is wet and the spark is white and the resistance is out of spec, it seems like you are on the path to a new coil.


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## thenne1713 (Dec 13, 2022)

Homer6679 said:


> I compared to it to the service manual spec and it was super high. Thanks for your input, how do you test coils then if resistance is a bad test?


NOW YOU VERBALIZED THE QUALIFIER, "compared to service manual spec" is grounds enough to replace coil/ magneto, if confident that meter/ meter leads are accurate enough. If it was the cause, it will also resolve the problem.


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