Your Generator Didn't Fail. The Install Did.

You've Probably Already Replaced the Spark Plug

If you're searching "generac portable generator won't start," there's a decent chance you've already swapped the plug. That's the instinct—when a scooter won't fire, it's the plug, isn't it?

But after four years reviewing generator install packages as a quality lead for a facilities management company, I keep seeing the same pattern: the units that quit during an outage almost never had a bad engine. They had an install that was treated as a formality.

About 200 packages cross my desk a year before contractors get final payment. Last year, nearly a third came back for rework. And the reasons almost never pointed to the machine.

That's a hard pill to swallow when you've already spent $4,000 to $18,000 on the unit alone—cost for a Generac generator varies by size and configuration (prices as of early 2025; verify locally). You expect it to work. But the failure usually started long before the generator was ever on the slab.

Where the Real Failures Live

I'm not saying engines never fail. Control boards fail, voltage regulators fail. But those are the exceptions in my stack. The bigger pattern lives in the layer around the machine—the stuff you can't see on a spec sheet.

Grounding That Was Never Verified

Grounding is the one everyone skips. It's invisible when it's right and invisible when it's wrong—until a surge hits and your control board fries.

When I ask for ground test data, I get a blank look more often than not. The wire was connected, the box was checked, done. If you want to know how to check ground with a multimeter, the basic test is simple: kill the main feed, set the meter to resistance, touch one lead to the ground terminal and the other to bare metal on the frame. It should read near zero. If it's tens of ohms or more, the grounding path is suspect.

That's a first check, not a substitute for a proper ground resistance test—I'm not an electrician, and that test requires a dedicated instrument. But it tells you whether someone, at any point, actually verified anything.

Ventilation That Was Eyeballed Instead of Measured

Every standby unit has clearance requirements for intake and exhaust air. I've seen units installed six inches from a wall because the installer eyeballed it. The unit runs hot, the winding fails, and someone blames the generator. A tape measure would've caught it in three seconds.

The Power Strip Problem

This one's small but telling. A few months back, a maintenance tech flagged a portable generator setup where someone had plugged in a power strip without surge protection. It worked fine—until a voltage spike took out the downstream equipment. The strip cost $20. The repair cost $600.

It's the same logic as the grounding issue: the thing that was skipped was invisible right up until it wasn't.

The Paperwork Gap

Here's one that surprises people. I've seen installs where the test data existed but was never filed. The contractor did the ground test, got the numbers, and then the paperwork vanished. From a quality standpoint, that's almost as bad as not doing it—because when something goes wrong, the data is your only proof that the system was set up correctly.

One commercial site had a generator failure and went back to the contractor for warranty support. The contractor claimed the install was done right. But when we asked for the commissioning report, there wasn't one. Their response: "We did the tests—we just didn't write them down." That's not a warranty position. That's a liability.

I assumed for years that "installed" meant "verified." It took a failed audit to show me those are different things. Installing something means it's physically there. Verifying it means someone proved it works to spec.

What It Actually Costs You

Here's the part the invoice never shows.

When you look at generator pricing, you anchor on the unit number. But the install is often 30–50% of the total, and cheap bids cut exactly where you can't see.

I've watched a residential rework bill hit $2,200 because the ground rod was driven in the wrong spot and had to be relocated. I've seen a commercial site lose three days of operation when the transfer switch wiring wasn't properly isolated and the utility refused to energize it.

Then there are the soft costs. If your generator fails during an outage, you're not just out the cost of the machine—you're out the power reliability you actually paid for. For a commercial site, that could mean frozen inventory, missed shipment deadlines, or a hotel full of guests wondering why the lights are out.

And the warranty question is the one that stings. If the failure traces back to the install—bad grounding, poor ventilation, incorrect transfer switch wiring—you may discover the manufacturer's warranty doesn't cover the damage. It's not the machine's fault. So why would it be?

One more: the cost of waiting. The longer a bad install goes unchecked, the more the damage compounds. A grounding issue catches a surge, and now you're replacing a control board and a grounding system. A ventilation issue runs hot for six months, and now the alternator is on its way out. The small skip becomes a major repair.

I keep coming back to the same conclusion: the cheapest install is usually the most expensive one. Not always—but often enough that I've stopped being surprised.

What to Actually Ask For

This doesn't have to be complicated. The basics haven't changed, even as the equipment has gotten smarter.

If you're buying an install, ask for the commissioning report. Not the invoice. Not the "system is operational" letter. The actual test data:

• Ground resistance readings at the rod and at the equipment
• Voltage drop at full load
• Ventilation clearance measurements
• Transfer switch isolation test results

Get the numbers—the actual readings, not a box checked "verified." If a contractor can't produce them, they either skipped the tests or never recorded them. Neither one is a good sign.

The good news is the industry has moved in the right direction. Ten years ago, commissioning meant turning the unit on and watching it run for five minutes. Today, the better installers do load testing, thermal imaging, ground verification, and formal documentation. The gap is between the ones who do it and the ones who don't. Your job as a buyer is to tell the difference before you sign.

If you already own the system, you can do a few checks yourself. A multimeter will tell you if the grounding path is intact—the test I described earlier. A visual inspection of the ventilation clearance takes five minutes. And if you're using a portable unit for backup, plugging sensitive electronics into a power strip without surge protection is a bet you don't want to take.

This approach worked for us because we manage multiple sites and can push back on contractors. If you're a one-off buyer, you may get more resistance. But asking costs nothing, and the response tells you a lot about who you're dealing with.

What was best practice in 2020 doesn't apply the same way now—the equipment has changed, the codes have updated, the install standards have tightened. But the fundamentals haven't: verify what you paid for. Get the numbers. And don't assume the spark plug is the problem just because it's the easiest thing to check.