Birken Vogt
We have a 22 (24?) kw Evolution liquid cooled unit in the field that is having a hard time opening into the pressure of a regulator that likes to creep up a little.

We already replaced the regulator once but it still does not get along with the new regulator.  So I was wondering if you guys know the part number or whatever for the taller, presumably stronger solenoid coil.
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murphy
The coil just enables the regulator to open, it does not open it.  It is called a demand regulator and only opens when it receives sufficient vacuum from the engine.  When were the engine valves last adjusted?  An incorrect adjustment can reduce the vacuum making it difficult or impossible for the regulator to flow gas.  An air leak in the path from the regulator to the engine can also cause the same problem.
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Birken Vogt
The electric coil I am talking about lifts the solenoid valve on the 3/4" gas inlet.  There is a taller one than the usual 3/4-1" tall one, I have seen it somewhere.  I understand it was created just to deal with this problem.  This unit is brand new and not anywhere near valve time and the 2.4 Mitsubishi is hydraulic anyway IIRC.  It also has the electric primer but if the main valve can't open the primer does no good.  The other test of course is if we bleed off a little pressure on the fuel inlet hose then it starts right up.
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Peddler
I don't know the number for the stronger solenoid off hand but can look in my parts bins in the morning and give it to you as well as the plunger that must also change.  What pressure does it creep up to?  I have had many liquid cooled units where the wires in the secondary gas primer valve are not making good contact which will cause starting problems.  But to your situation you can test the creeping gas pressure issue by switching the source for the gas priming (enriching) valve from below the primary solenoid to above.  This will auto vent any high pressure into the intake manifold while cranking and allow the primary solenoid to open just to prove your theory. 
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78buckshot
I have also found a number of the cold start solenoid wires loose, the creeping gas pressure is a red flag, is it Natural high pressure (2 psi) stepped down or LP?
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Peddler
The heavy  duty solenoid part number is 0J7137 and the plunger is 0J8315A.
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Brian Baughman
Birken Vogt wrote:
We have a 22 (24?) kw Evolution liquid cooled unit in the field that is having a hard time opening into the pressure of a regulator that likes to creep up a little.

We already replaced the regulator once but it still does not get along with the new regulator.  So I was wondering if you guys know the part number or whatever for the taller, presumably stronger solenoid coil.


Did the new regulator have an internal relief valve?
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Birken Vogt
It is LP gas, new regulator, all LPG regulators have internal relief by code these days. 

I did not switch the prime to before the electric solenoid because IIRC the prime travels a distance in a rubber hose before hitting the electric solenoid valve with cheesy little spring clips and I did not want that kind of thing without any auto shutoff valve.  We did prove it is pressure related by briefly loosening the gas line at the inlet which does the same thing anyway.

All wires were checked in excruciating detail to be sure it was not a loose connection.  The enrichment valve was also changed out in the initial testing process long ago because it was the most obvious thing.

We even set a tiny 1/8" ball valve with a plug on the regulator test port so we could check for long term creep without losing our measurement in the process of making the connection but have not had the opportunity to do that yet.
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78buckshot
So at this point you don't have a pressure figure? what is the primary regulator set at? You can set the primary down a little as long as it can keep up with the highest anticipated demand - 10psi is normal but I have some down to 8psi, I shoot for 13 - 13 1/2 in. static on the secondary. If it's creeping it's a bad regulator.
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Birken Vogt
Primary is 10 psi and I put a permanent gauge on that too just to see if it was not the cause of the creep.  The secondary has been replaced once already due to creep and the line blown out at that time.  The thing does sit on the south side of a shed in a very hot place so idle speculation is that the hot sun might creep up the secondary pressure after a long time shut down but I kind of wonder if that is enough to cause this problem.  This place is so far out there we don't want to take any unnecessary trips.  This is the electrician telling me the facts, I trust him to troubleshoot what I tell him correctly but he does not have the experience and I do not have another reason to drive out there so we wait.
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78buckshot
You might be on to something with the heat related pressure rise. I assume the primary line is underground but once it's above grade then it could in theory increase the pressure between the secondary reg and the generator due to sunlight /ambient. Cooler weather might give you more info and you could experiment with shading the LP lines and regulator.
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Peddler
I often find "Maxtrol" regulators on LP systems which come from the factory with a leak preventing vent.  This often fails with that vent clogged by mud daubers but it will also prevent the diaphragm from moving fast enough to keep the downstream pressure from spiking.  They should all have a screened vent outdoors and be several feet from the generator to allow for some cushion on the solenoid valve closing.  IF the pressure is creeping up then it is a bad regulator.  We always use a Fisher second stage regulator on the LP systems and have very little trouble unless they pipe the vent of under ground and it fills with water which will make the generator surge.  I do not believe the gas would gain enough pressure from thermal heating to cause a problem. 
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Birken Vogt
Peddler wrote:
The heavy  duty solenoid part number is 0J7137 and the plunger is 0J8315A.


Thanks for that, what is the part number for the gasket?  And is there a separate tube part number that the plunger rides up and down inside the solenoid coil or is it all part of the coil assy?
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Peddler
The gasket is the same as the original solenoid and I almost never have to replace them.  The plunger is the only other part you need.








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MacL
Be sure you have a good battery with clean connections.  This too can cause not enough juice to get to the solenoid.  At best, it gets about 10 volts.  So any battery or battery connection problems can cause the solenoid not to pull the plunger in, especially when coupled with that it has to work against gas pressure.  If this is the case you may also notice slower than normal cranking.
State your problem, not your diagnosis.
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