Problems with 20kw gen-set

[Toyboy]

I have a 2 year old Generac 20kw installed and running on NG that has not started for scheduled weekly exercise 2 out of the last 4 weeks. It cranks over but will not fire up. It turns, just won't catch. Try's for 5 times before it cancels out the exercise. Now before you start running Generac down let me fill in the blanks.

For the last two years it has faithfully run it's scheduled 15 min exercise without a hitch. Now I live in Northern WI, and ever since before Thanksgiving it's been colder then a well diggers arse, with temps running between +15 to -30. Most days it never gets above -6. Nasty cold spell which you already know about.

Now when it was installed, the gas company replaced the meter on the house with a larger one to accommodate the increased demand. The unit has a regulator that was originally set at 7" of water. Generac calls for 5 to 7" of water column (0.18 to 0.25 psi). Apparently the unit has a auto shut down if gas pressure gets too high. Gas people came out today and checked for pressure and volume and all is within spec. They did back down the pressure to the gen-set to 6" to see if that would make a difference. They thought it may be too close to the high side. I won't know for sure unless I go fire it up at -25 tomorrow or till next Sunday if it did.

Do any of you gen-set gurus have any ideas on what may be the issue, or do you think by lowering the NG pressure may do the trick?

Ideas?? Thoughts?

 

[zzvyb6]

Valve closed, no ignition, air in line, cosmic rays, global warming, Affordable Generator Act.

 

[RJFEJF]

Load test your batt, and check your trickle charger.

 

[Toyboy]

Battery is good and so is trickle charger. It cranks over ok, it just acted like it's being starved for fuel. The first time this happened ( 2 wk ago) it would rev up & die. Done that a couple times before it caught and stayed running.

This time it popped a couple times and backfired through muffler. Went outside and hit manual start and I'll bet it didn't turn two revolutions and away it went. Perplexing!

 

[RJFEJF]

Did you try changing the spark plugs? I had one bad spark plug out of the 2 plugs and it acted the same.

 

[Toyboy]

No I didn't. The unit only has around 30 run hr on it (12 hr yr). It's only run the exercise cycle because we've not had an outage since it's been installed. I did service oil & filter this fall (Mobil1 5w30), but the air filter looked new so I left that alone.

 

[Industrial Toys]

A friend of mine in the commercial generator business would say, the problem is that it is a Generac!
Has nothing good to say about them.

How many RPM does the unit run at, just out of curiosity?

I actually installed one (on Propane) at the request of a customer. My feeling, and hearing the thing run at 3600rpm is that it won't last long! Maybe the regular excercise has already worn it out.

 

[RJFEJF]

I would put in new plugs every year. I had skipped 1yr and wouldn't ya know it was 1 bad plug and both plugs did look good before the change out. You need fuel, air and spark, this is usually were problems occur, barring any mechanical break down.

 

[tcartwri]

Nat gas and propane motors hate the cold. end of story.

 

[Toyboy]

A friend of mine in the commercial generator business would say, the problem is that it is a Generac!
Has nothing good to say about them.

How many RPM does the unit run at, just out of curiosity?

It's a V Twin rated 36hp at 3600 rpm.

I'm not into bashing any brand, I just want to sort out what the problem is with mine.

If I needed a commercial gen-set it would be a Cat.

 

[Toyboy]

I would put in new plugs every year. I had skipped 1yr and wouldn't ya know it was 1 bad plug and both plugs did look good before the change out. You need fuel, air and spark, this is usually were problems occur, barring any mechanical break down.

You got me thinking on that one. I just figured with less than 30 hr on this one, that plugs would be considered brand new yet.

At our former home, I had an 8kw (propane) Generac installed in 1994 before I retired, and all that ever needed was oil/filter changes. Never missed a beat in 10 yr before we sold, and we did have outages there.

 

[PapaPerk]

It's a V Twin rated 36hp at 3600 rpm.

I'm not into bashing any brand, I just want to sort out what the problem is with mine.

probably made by Briggs.

 

[buickanddeere]

Prime it with a snort of gasoline and see what happens.

 

[Toyboy]

probably made by Briggs.

Generac manufactures this one and several others they use, don't know about all of them. They have a plant in So. Wisconsin.
My 8kw did have a Briggs Vanguard for power.

 

[Toyboy]

Prime it with a snort of gasoline and see what happens.

Ahhhhh NO

 

[kenmac]

Have you Checked to see if you are even getting fire at the plugs

 

[Toyboy]

Have you Checked to see if you are even getting fire at the plugs

Well it did run finally, and I shut it down and re-started it several times. So I would have to say yes there is fire at the plugs.

 

[Ken]

Well it did run finally, and I shut it down and re-started it several times. So I would have to say yes there is fire at the plugs.

Do you have a elec. gas valve that turns on to allow NG into the carb. or use the vacuum so the engine turning over opens the gas valve? the line pressure seems reasonable so next time recheck the method feeding the fuel to engine.
I have worked with Onan Kohler and these were seldom unreliable in starting when power failed. and they sat outside in temperature colder than what you have stated.
Worn has been mentioned I would doubt this NG fuel causes very little wear in cylinder. maybe recheck the type of oil used . new plugs help when there is problems .
My only experience with your brand of generator was caused by lightening that was a relay in starting circuit. that held the fuel valve closed.
Use a set method to check the engine fix any problem found then keep a record of repairs for next time in need .
ken

 

[zzvyb6]

So, with manual start, its 'OK'. That means fuel and ignition are good if manual controls are engaged. What parts of the remote/schedule start system are shared and what parts are separate from the manual start system. Could it be just a poor solenoid secondary?

 

[grsthegreat]

A friend of mine in the commercial generator business would say, the problem is that it is a Generac!
Has nothing good to say about them.

How many RPM does the unit run at, just out of curiosity?

I actually installed one (on Propane) at the request of a customer. My feeling, and hearing the thing run at 3600rpm is that it won't last long! Maybe the regular excercise has already worn it out.

you generac naysayers drive me nuts. Ive been installing generators for nearly 30 years. Big commercial units and smaller residental units. Ive installed Honeywell, Generac, Siemens, you name it.

Funny thing is, alot of other manufacturers use Generac manufactured engines and parts. Generac is the WORLDS largest generator manufacturer.

Ive never ,... never... have had a call that a unit failed due to generator manufactured issues. they have always been from misuse or neglect. I just fix two units that wornt working after a power failure. The owner NEVER changed oil or checked batteries since they were installed. They were installed 7 years ago. After servicing them, they both fired right up.

Nothing will last if its not maintained, and most people forget their generators.

Now for the OP's issues. I have run into similar issues in the past. I assume that this is an air cooled unit, so ill not worry about heaters (extreme cold kits). Things to check

1. check that gas/fuel solenoid is opening.
2. Spark plug foul and check gap
3. Fuel pressure set wrong
4. The manual talks about checking #14 wire on the control harness to make sure its connected, but this is quite a chore to do.
5. A week battery will cause a weak spark on the sparkplug. You can do a spark plug test like you do with a car to check spark.

just for your info, ive also fixed a unit where the installer used pipe dope not rated for NG on his generator install, and a large clump of it broke free and obscured gas flow. Found that after unhooking the fuel lines. This made the generator act erratic....rev and stall, hard starts.