How to get propane electric generator started.

I have bought a house that has an electric generator. There was no info passed on to me by the previous owner. It is a whole house generator with manual transfer switch and a Briggs and Stratton propane engine. The generator has worked 2 or 3 times when we have lost power. Now I haven't started it in while and it wouldn't turn over. I put a new battery in it and now it turns over and it tried to start, but now it just turns over. Could it be flooded? Could there some sort of reset that kicked in when it wouldn't start? Thanks

Since its propane it shouldn't flood like a gasoline engine can. There should be a solenoid on the gas line that opens during start/ run cycles. Other than that, check for the 3 things you normally would(fuel/air/spark).

You should get the manual for it, So you know how the safety system works.

Make sure the kill switch is Off.


Good Luck.

Check your propane tank and follow the line from the generator back to the tank if you can. Does it have a manual shutoff valve anywere along the line that may have been shut off.
If I were there trying to start it......I would check for spark at the plug wires as it cranks. If it has spark it would lean you to assume it is not getting fuel. Carb cleaner in a spray can can be used and it is safer than either.......spray the carb cleaner into the air cleaner or directly in the carb and see if it fires off or starts for a few seconds. If it does you definitely have no fuel flow. They do have a solenoid that opens to allow propane to flow. They also often have a demand regulator. Looks like a pancake shaped item. It has a vent to the atmosphere that must be open and not plugged. It is a safety item.....propane will not flow if it does not operate properly and a plugged vent will cause it to not open. Bugs can plug up a vent tube.....and they often do on RV's that have propane powered generators......if it is very cold......nat gas and propane generators often are difficult to start.....low gas pressure and no cold weather enrichment cause issues sometimes........Have fun...be safe...propane is dangerous and if you smell gas you will know it...so be carefull....

That was nice Rich. Good advice.

Another thing that can shut them down is being Low on motor oil.

If you try to start it and do not smell propane, then it is most likely a No fuel problem.

Spark is easy to check, but should be checked with the Gas OFF, just for safety.


Have Fun.

Thanks Don...I work on generators everyday......21 years in the business...

Low oil will cause them to shut down but they will start first and shut down in a low oil shutdown. Almost all small engines override the low oil shutdown during startup.....

I have also repaired engine driven welders for all of those 21 years...and they do the same thing.......

We sell Briggs homeowner units......12-20KW and all air cooled engines. I completed an engine replacement today on one.....20KW.....engine broke both rods and the cam....nat gas powered....

Rich B said:

Thanks Don...I work on generators everyday......21 years in the business...

Low oil will cause them to shut down but they will start first and shut down in a low oil shutdown. Almost all small engines override the low oil shutdown during startup.....

I have also repaired engine driven welders for all of those 21 years...and they do the same thing.......

We sell Briggs homeowner units......12-20KW and all air cooled engines. I completed an engine replacement today on one.....20KW.....engine broke both rods and the cam....nat gas powered....

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Sounds like fun.

Will you take the motor apart to see what happened to make it fail ?

Not much lube in the upper part of a motor that runs on Real "Gas".

I think that good Synthetic oil should be used in generators and small engines applications.


Lead did that job , in the day.

Don, I did take the engine apart. Briggs is paying for the repair. We were asked to take it apart to confirm the damage. I spent many years as a mechanic and engine builder. I race cars and have for 40+ years and have built my own engines all those years. So engines are right in my wheelhouse.....

Small engines like this routinely use aluminum rods with no bearing inserts. On this engine as I have seen many times......the rod to crank pin area went bad first but we don't know why.....It was low on oil as they do use oil if run under load for an extended time. In theory....the low oil pressure shutdown should stop damage like this......We know from experience it may not. The rods started to seize on the crank and one came apart and broke the other as well as the cam and also damaged the block.........

I built race engines and did machine work for a living for a good part of my working life......Doing a post mortem on an engine that fails is educated guesswork.....This one is pretty typical.......

Air cooled small engines use oil when worked hard.......and forget the snake oil or special oils......if it runs low it will blow.....LOL

Well, thank you for the very helpful advise. The inline gas valve is open. When I was turning it over I could smell propane. I did pull the plug and it was all wet with fuel. I dried it off but I did not check for spark, so that will be my next move. My next step is to take the plug out and put a new plug in there. The oil level is fine because I just changed the oil. It was very cold when I was trying to start it, so hearing your words of advise, that might have something to do with it. I have been trying to find an online manual, but have no engine or generator manufacture info to go on because all of the tags have faded. I am assuming it is old, so maybe it is time to upgrade and get a new generator and a new automatic transfer switch. The manual transfer switch is such a bad idea. It really defeats the purpose of having a back up generator because you have to be home to throw the switch. Thanks for you help.......Karl

Propane powered engines hate the cold. I have 2 propane powered forklifts in my shop. If I let the one I use most sit outside in the winter it is very hard to start and usually will need some help to get started.
You should not see anything wet on the sparkplug but it may be condensation. We do have issues with small engines needing spark plugs much more than what you would consider normal. My co-workers change them a lot on homeowner type generators.
A manual transfer switch was common in the past but with modern electronics automatic switches are now the norm. Old switches had relays and timers and lots of components to fail. We service many buildings with big generators and big switch gear. I have been in buildings with all the old stuff for elevators and phones. Banks of relays all open to the air and endless wire and terminals. Solid state is good.....Board fails replace it....

We sell Briggs home generators and switches. They are totally automatic.....but do need to be serviced and maintained if you expect it to work in a power failure.

khandy said:

Well, thank you for the very helpful advise. The inline gas valve is open. When I was turning it over I could smell propane. I did pull the plug and it was all wet with fuel. I dried it off but I did not check for spark, so that will be my next move. My next step is to take the plug out and put a new plug in there. The oil level is fine because I just changed the oil. It was very cold when I was trying to start it, so hearing your words of advise, that might have something to do with it. I have been trying to find an online manual, but have no engine or generator manufacture info to go on because all of the tags have faded. I am assuming it is old, so maybe it is time to upgrade and get a new generator and a new automatic transfer switch. The manual transfer switch is such a bad idea. It really defeats the purpose of having a back up generator because you have to be home to throw the switch. Thanks for you help.......Karl

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Are there two plugs? Most of the smaller 8 to 20kw gensets have a vanguard that I have seen and have 2 spark plugs. Just a reminder so you don't overlook that possibility.

khandy said:

Well, thank you for the very helpful advise. The inline gas valve is open. When I was turning it over I could smell propane. I did pull the plug and it was all wet with fuel. I dried it off but I did not check for spark, so that will be my next move. My next step is to take the plug out and put a new plug in there. The oil level is fine because I just changed the oil. It was very cold when I was trying to start it, so hearing your words of advise, that might have something to do with it. I have been trying to find an online manual, but have no engine or generator manufacture info to go on because all of the tags have faded. I am assuming it is old, so maybe it is time to upgrade and get a new generator and a new automatic transfer switch. The manual transfer switch is such a bad idea. It really defeats the purpose of having a back up generator because you have to be home to throw the switch. Thanks for you help.......Karl

Click to expand...

The Briggs engines have the Model number Stamped into the Flywheel cover/housing/shroud. Unless it is rusted out, you can read it.

If it is a older model that uses points, then the Points Plunger may need replaced. The plunger swells up and sticks, then the points will not close, so no spark.

You can get a kit that includes the Plunger and points.

Most of the newer engines have electronic spark modules. They do go bad, but replacement is cheaper than a new motor.

Like Rich was saying, It sounds like you have water in the cylinder, and on the plug.

You can remove the spark plug, then turn the engine over, that will blow out any moisture in the cylinder.

You should make sure that you do not kill the battery by cranking it to long. If the battery voltage gets Lower than 12.0 Volts, then you should recharge it, or it can freeze up and bust.


Good Luck.