78buckshot
Do any of you techs have the part number for the so-called "heavy duty" or stronger fuel solenoid coil for the air cooled models? Is it obsolete, still available? The only one I come up with is the current 0f5022. 
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Peddler
The coil is 0J7137 and the plunger and spring are 0J8315A.
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78buckshot
Thanks peddler.
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Birken Vogt
What is the story behind this? Never heard of it before.
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nrp3
Is this the taller one that comes on the newer generators?
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Peddler
This solenoid will open against higher gas pressure.  If you have a generator on a 2 PSI gas system and HP gas is getting by the regulator for what ever reason these will some times open when the originals will not.  I'm not saying they would open against a full 2 psi but I have tested them to open against 20" wc. 
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78buckshot
 NRP3, I have used one in the past for a 4390 - maybe 6 - 7 years ago. I was looking for the info to assist another site member.
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Birken Vogt
Peddler wrote:
This solenoid will open against higher gas pressure.  If you have a generator on a 2 PSI gas system and HP gas is getting by the regulator for what ever reason these will some times open when the originals will not.  I'm not saying they would open against a full 2 psi but I have tested them to open against 20" wc. 


Any idea which models came with it already and which could be upgraded?  I had this issue recently on a 22 kw liquid cooled Evolution but it was basically brand new so probably already had it I suppose.
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Peddler
Not all the new units are using the stronger solenoid or at least they weren't.  It is about twice as tall as the old style.
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Wireform
This stronger coil/longer plunger got my attention as to possibly my issue:
My generator is pre stepper motor design. The linkage is all free and have eliminated that area. When it starts it has a relatively short crank but the rpm starts up at around 3000 and the gets to the 3600 or just about. I was wondering if the solenoid is weak and or the plunger isn't smooth anymore so possibly not getting enough gas initially. How can I test that. I have a digital manometer and I'm more than capable. Where do i start ? Is this called hijacking the thread ??
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78buckshot
It will be next to impossible to detect a solenoid issue with a manometer unless it's not opening at all. The engine pulses cause wild readings as it's cranking and during initial rev-up. Once the unit is running steady state the manometer settles down to readable levels. I would say that with your description of relatively quick starting that the solenoid is probably OK. Has your unit faulted on "overcrank" or "overspeed" at any time? How long does it take to reach correct speed?
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Wireform
Thanks 78buckshot
Overcrank never and overspeed happened back in  middle of hurricane Sandy when the linkage cracked off by the governor side where it goes through the the hole. Had at one time slightly longer cranks and rectified that with a valve adjustment and ever since it has been short even in cold temps. Will have to time the rpms on the weekend and get report back. But please clarify what you mean by pulsing and wild readings as it cranks as I'll observe that as well. Thanks in advance, Allan. 
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78buckshot
We need a little more info, model#, serial#, type of fuel. Some of the older units needed 11.5 - 12.5 in. w.c. with all fuels, depending on age it could be spec'd at 7.5 in. w.c. for natural gas and 12.5 in. w.c. for propane. I don't want to mislead you with incorrect spec's. The static fuel pressure will drop sharply and bounce with the intake pulse from each cylinder as the engine is cranking, as the engine begins to speed up the pressure will drop and recover within a second or so, it's difficult to diagnose anything from those readings. What we look for and what Generac spells out is a difference between static pressure and steady state running pressure, no more than 1 in. w.c. pressure drop. That will normally confirm that the fuel supply volume, pressure, regulators, and piping are correct.
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Wireform
78buckshot wrote:
We need a little more info, model#, serial#, type of fuel. Some of the older units needed 11.5 - 12.5 in. w.c. with all fuels, depending on age it could be spec'd at 7.5 in. w.c. for natural gas and 12.5 in. w.c. for propane. I don't want to mislead you with incorrect spec's. The static fuel pressure will drop sharply and bounce with the intake pulse from each cylinder as the engine is cranking, as the engine begins to speed up the pressure will drop and recover within a second or so, it's difficult to diagnose anything from those readings. What we look for and what Generac spells out is a difference between static pressure and steady state running pressure, no more than 1 in. w.c. pressure drop. That will normally confirm that the fuel supply volume, pressure, regulators, and piping are correct.

Generac model# 044563, Serial#4308603 NG, 425 cfh gas meter, with 10 feet of 1" black pipe .
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Peddler
I don't think you have a fuel solenoid problem, if you did it wouldn't start at all.  Your governor should be set for about 64-65 Hz with no load and the butterflies should basically stay wide open to it gets very close to hat RPM.  If I were to guess I would say the coils are failing and it is starting on one cylinder and then the other cylinder comes in after a few seconds or it is simply running on one cylinder period.  You should check exhaust temps and both sides should be equal roughly and at no load be around 700 degrees.  On those older units you can adjust the gas at the demand regulator and perhaps one of those is open too far and flooding the engine until some heat builds.
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78buckshot
Thanks Peddler, that's where I was heading next.
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Wireform
Thanks peddler and 78buckshot. 
So I see where this is going. Can u give me a pecking order of this recent discussion where to begin. If it's the coils, I guess changing them both would be good thinking. If I do the coils it will be done in the winter thaw or just wait for the spring. 
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Peddler
Always change both coils because it is a miserable job.  An infrared heat gun on the exhaust tubes is the best place to start.
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