Propane generator regulator questions

[Code54]

I have a 8 year old 20 KW Briggs whole home generator with a Vanguard 993 motor, and we have been having some issues with it starting. It will start, but it either takes a rather long crank or 2 tries. You can also get a whiff of propane while it tries to start. We narrowed it down to needing a new regulator on the generator. This started with it throwing a low voltage code, and it appears it was having some trouble at full power keeping the RPMs up. A generator tech from the local company came out and looked at it and said he thought we had a bad motor and it needed to be replaced (5k for new motor or 9k for a new unit). The generator has 440 hrs on it, so I decided I needed to look into this more. Got a 2nd opinion from another company and their tech felt it was the electronic throttle control and that the motor was fine. I changed out the throttle control but no luck. I ran a compression test, one cylinder was 148, and the other was 150 psi. Oil pressure after start up at 3600 is 32 psi. Once fully running it is smooth and sounds good. I also checked and lashed the valves to make sure they were in spec. At this point, my understanding (from a fellow who fixed propane forklifts) is that when you have a regulator issue, it can cause hard starting because the diaphragm is not metering the propane correctly and can basically flood the engine on start-up. So we are now planning on changing it out.

I found the factory part BUT it is crazy expensive ($300), and even places that show it "in Stock" don't seem to have it and say it won't be available until late December. Here is the factory one (it is sort of down in a hole so not a great picture)

I found this one on Amazon

I noticed it is the same model (KN) but it appears to have a 7/16 orfice, whereas the Briggs one is 9.95mm. Does anyone know if I can just remove the original orfice and put it in this one? I am GUESSING it goes in the bottom side where that treaded plug is at, correct?

I don't care if I need to buy a gauge set to get the pressure adjusted but is there anything else I may need? I am familiar with gas motors and comfortable with piping gas lines, but I have never messed with regulators or taken one apart. Can't say I know much about propane either, but it looks like it is time to figure it out.

Thanks in advance for any help you can offer!

 

[LittleBill21]

i'd buy a drill bit and drill it if you can't get it to remove.

 

[ponytug]

I have a 8 year old 20 KW Briggs whole home generator with a Vanguard 993 motor, and we have been having some issues with it starting. It will start, but it either takes a rather long crank or 2 tries. You can also get a whiff of propane while it tries to start. We narrowed it down to needing a new regulator on the generator. This started with it throwing a low voltage code, and it appears it was having some trouble at full power keeping the RPMs up. A generator tech from the local company came out and looked at it and said he thought we had a bad motor and it needed to be replaced (5k for new motor or 9k for a new unit). The generator has 440 hrs on it, so I decided I needed to look into this more. Got a 2nd opinion from another company and their tech felt it was the electronic throttle control and that the motor was fine. I changed out the throttle control but no luck. I ran a compression test, one cylinder was 148, and the other was 150 psi. Oil pressure after start up at 3600 is 32 psi. Once fully running it is smooth and sounds good. I also checked and lashed the valves to make sure they were in spec. At this point, my understanding (from a fellow who fixed propane forklifts) is that when you have a regulator issue, it can cause hard starting because the diaphragm is not metering the propane correctly and can basically flood the engine on start-up. So we are now planning on changing it out.

I found the factory part BUT it is crazy expensive ($300), and even places that show it "in Stock" don't seem to have it and say it won't be available until late December. Here is the factory one (it is sort of down in a hole so not a great picture)

View attachment 1403882

I found this one on Amazon

View attachment 1403883

I noticed it is the same model (KN) but it appears to have a 7/16 orfice, whereas the Briggs one is 9.95mm. Does anyone know if I can just remove the original orfice and put it in this one? I am GUESSING it goes in the bottom side where that treaded plug is at, correct?

I don't care if I need to buy a gauge set to get the pressure adjusted but is there anything else I may need? I am familiar with gas motors and comfortable with piping gas lines, but I have never messed with regulators or taken one apart. Can't say I know much about propane either, but it looks like it is time to figure it out.

Thanks in advance for any help you can offer!

First, I think that you are probably right about the regulator being the issue, but I would check an few other things first.
First, I would check that your propane tank is not low. Second, I would double check that the pressure out of the main liquid LPG to gas regulator on the tank to make sure that it is at the right pressure. (Most propane companies will do this free, but check.) Third, have you checked the wiring connections on the solenoid and watched it move when the engine starts?

I do have one question: is the main propane pipe from the tank to your generator the correct size specified by the generator manufacturer? (I've seen installations where the pipe wasn't large enough, and / or the pipe had elbows too close to the generator. The symptoms were similar to what you are experiencing.)

All of these point to not enough propane getting to the engine, either due to low pressure, a clogged orifice, or plumbing that has restrictions in it, or possibly a bad solenoid / controller.

Natural gas and propane regulators have different sized orifices, and are normally an easy swap. I would double check with Briggs/Vanguard that the 9.95mm (0.391") is correct.

Good luck!

All the best,

Peter

 

[Code54]

Thank you. The tank is a 500 gallon and is sitting at 60% currently. The 2nd company that stopped said the piping is sized correctly and it did seem to work fine for about 8 years. I will call the propane supplier and see if I can get them to check the pressure, that is a great idea.

I checked the solenoid, and it seems to click over so I believe it is working correctly.

I can check on the size, that is just what the sticker said, so I was going with that, but would be good to check. Since both regulators are model KN do you think I cna just use the Amazon one? We really want to get this generator up and running due to the storms that have been pushing through recently, so I was looking for a quick solution rather than waiting until December when Briggs will have a factory part.

Thank you again for the info.

 

[kenmac]

Thank you. The tank is a 500 gallon and is sitting at 60% currently. The 2nd company that stopped said the piping is sized correctly and it did seem to work fine for about 8 years. I will call the propane supplier and see if I can get them to check the pressure, that is a great idea.

I checked the solenoid, and it seems to click over so I believe it is working correctly.

I can check on the size, that is just what the sticker said, so I was going with that, but would be good to check. Since both regulators are model KN do you think I cna just use the Amazon one? We really want to get this generator up and running due to the storms that have been pushing through recently, so I was looking for a quick solution rather than waiting until December when Briggs will have a factory part.

Thank you again for the info.

you can use an inches of water column gauge and check the supplied gas pressure from your tank regulator to this regulator while the generator is running. There should be a test port to allow you to check incoming gas pressure. That would let you know if the tank regulator is keeping the correct supply to this regulator.

Do you know how much gas pressure your tank regulator should be supplying this regulator ? (I see it states 8 oz which is around 13.8 inches wc)

Do you know how much gas pressure this regulator should be supplying to the engine during operation ?

 

[Code54]

I do have the install manual and believe it gives the specs for pressure so I certainly can find out. It has always been a little slow to start so maybe there is a pressure issue, so checking everything from the tank to the generator is a good idea and something we will do. I just ordered a gauge and it should be here Sunday.
Thanks

 

[Chilliwack Murray]

The orifice in the new regulator is larger so it won't be an issue, smaller would mean it couldn't deliver the required volume of gas. You should be able to swap it if you want anyway.

The most common reason regulators fail is oil contamination. The usual symptoms are hard starting due to the reg sticking but sometimes a gen will run good for 10 minutes or more then die or nearly die and pick up again, repeating over an over as oil in the line blocks the flow of gas until there is enough pressure difference for a bubble of gas to push through then the cycle repeats.

Check the line to the regulator and the regulator itself for oil, if there is oil in your tanks the new reg will fail as well. LP should not have oil but being a closed system, it's nearly impossible to tell if a pump on a truck or a filling station is leaking oil into the gas. I've seen dozens of tanks and regulators contaminated by a single truck that supplied all the customers in one area.

 

[1Mech]

Years ago I worked on propane forklifts, often the problems we found was mainly contamination as mentioned previously. As I recalled, we would clean them and maybe install a new diaphragm rather than replace them. Of course most shops these days opt for replacement rather than repair.
Can you buy a rebuild kit for it?

 

[Code54]

Thanks, everyone - I will check for oil when I get the new parts and go to install them.

They do offer a replacement diaphragm, but it was north of $300, which seems insanely expensive for what it is.

It sounds like the Amazon one should work since it is the same company and model. That is good because it saves me waiting for months. Any tips or tricks on setting the pressure?

Again, I appreciate all the help and information, finding much on "Briggs 20kw propane generator repairs" is a bit lacking on the web.....

 

[kenmac]

The orifice in the new regulator is larger so it won't be an issue, smaller would mean it couldn't deliver the required volume of gas. You should be able to swap it if you want anyway.

The most common reason regulators fail is oil contamination. The usual symptoms are hard starting due to the reg sticking but sometimes a gen will run good for 10 minutes or more then die or nearly die and pick up again, repeating over an over as oil in the line blocks the flow of gas until there is enough pressure difference for a bubble of gas to push through then the cycle repeats.

Check the line to the regulator and the regulator itself for oil, if there is oil in your tanks the new reg will fail as well. LP should not have oil but being a closed system, it's nearly impossible to tell if a pump on a truck or a filling station is leaking oil into the gas. I've seen dozens of tanks and regulators contaminated by a single truck that supplied all the customers in one area.

If the orifice is larger, It could supply too much gas and cause the motor to flood . Personally, I would stay with the factory recommended orifice