Duromax XP12000EH Troubleshooting: A Complete Guide!
Updated: February 11, 2026
The DuroMax XP12000EH is a powerful dual fuel generator that can run on both gasoline and propane. Like all generators, it can develop issues over time. This guide covers the most common problems and how to fix them yourself.
Contents
- 1 DuroMax XP12000EH Quick Reference Table
- 2 DuroMax XP12000EH Engine Will Not Start
- 3 DuroMax XP12000EH No Electrical Output
- 4 DuroMax XP12000EH Does Not Support Connected Devices
- 5 DuroMax XP12000EH Dual Fuel Troubleshooting
- 6 Conclusion
- 7 Frequently Asked Questions (FAQs)
- 7.1 What type of oil should I use in my DuroMax XP12000EH?
- 7.2 How often should I change the oil in my DuroMax generator?
- 7.3 Can I run my DuroMax XP12000EH on propane only?
- 7.4 Why does my DuroMax generator surge or hunt?
- 7.5 How long will a 20lb propane tank run my DuroMax XP12000EH?
- 7.6 Where is the best place to store my DuroMax generator?
- 7.7 What spark plug does the DuroMax XP12000EH use?
DuroMax XP12000EH Quick Reference Table
| Symptom | Most Likely Cause | Quick Fix |
|---|---|---|
| Won’t start at all | Fuel valve closed / Choke wrong | Open fuel valve, close choke for cold start |
| Cranks but won’t fire | Bad spark plug / Old fuel | Clean or replace spark plug, drain old fuel |
| Starts then dies | Low oil / Clogged carburetor | Check oil level, clean carb |
| Runs but no power | Circuit breaker tripped | Reset breakers on control panel |
| Surging/hunting | Dirty air filter / Bad fuel | Clean air filter, use fresh fuel |
| Won’t run on propane | Fuel selector position | Switch selector to propane, check tank valve |
DuroMax XP12000EH Engine Will Not Start
The engine of the DuroMax XP12000EH generator will not start due to the reasons below.
| Reason | Solution |
|---|---|
| Generator is not level | Place on a leveled surface |
| Engine switch is “Off” | Turn switch to “Run” position |
| Fuel valve is closed | Open the fuel valve |
| Choke is open (cold start) | Close the choke |
| Out of fuel | Refill the fuel tank |
| Low, old, or contaminated oil | Replace and refill engine oil |
| Spark plug dirty or broken | Clean or replace the spark plug |
If you’ve checked all of the possible causes and still having trouble, you need to take it to a qualified mechanic.
Reason 1: The Generator Is Not Level
When you run the generator on an uneven surface, the oil level sensor can misread the oil level as low. The low oil shutoff will then prevent the engine from starting even when there’s plenty of oil.
Solution:
Make sure you are running the generator on a leveled surface. If you must keep the generator on a sloped surface, insert some cardboard or wood piece under the lower leg of the generator to level it out.
Reason 2: The Engine Switch Is “Off”
It sounds obvious, but it’s easy to overlook. The engine switch needs to be in the “Run” position for the generator to start.
Solution:
Make sure the DuroMax XP12000EH generator engine switch is turned to the “Run” position before attempting to start.
Reason 3: The Fuel Valve Is Closed
If the fuel valve is closed, fuel can’t reach the carburetor and the engine won’t start.
Solution:
Turn on the fuel valve of your DuroMax XP12000EH. The valve is located above the recoil start, under the fuel tank. Turn the valve counterclockwise to open it.
Reason 4: Choke Is In Wrong Position
For a cold start, the choke needs to be closed. For a warm restart, it should be open.
Solution:
For cold starts, close the choke by sliding the lever to the left (you’ll find it on the left side of the recoil start). Once the engine warms up after about 30 seconds, gradually open the choke.
Reason 5: The Engine Is Out Of Fuel
Check the fuel level on your generator. If the fuel level is low or empty, the DuroMax XP12000EH won’t start.
Solution:
On the fuel tank, there are marks indicating upper and lower levels. If the fuel is below the lower mark, refill with fresh gasoline up to the upper mark. For best results, use fuel with no more than 10% ethanol.
Reason 6: Low, Old, Or Contaminated Oil
The XP12000EH has a low oil shutoff that prevents engine damage. If oil is low, old, or contaminated, the generator won’t start.
Solution:
Check the oil level using the dipstick:
- Unscrew the dipstick cap
- Wipe the dipstick clean
- Reinsert fully, then pull out to check the level
- If low, add SAE 10W-30 oil until it reaches the full mark
DuroMax recommends changing the oil every 20 hours of use or monthly. Here’s a helpful video showing the oil change process:
Reason 7: Spark Plug Is Dirty Or Broken
A dirty or damaged spark plug can’t create the spark needed for ignition.
Solution:
- Pull the spark plug cap to remove it
- Use the spark plug wrench (included with your generator) to unscrew the plug
- Inspect the plug – if cracked, chipped, or heavily worn, replace it with a compatible spark plug
- If just dirty, clean it with a wire brush
Not sure which spark plug to use? Check out our guide on RC12YC, RC14YC, and XC12YC spark plugs to find the right one.
DuroMax XP12000EH No Electrical Output
If your generator runs but produces no electrical output, here are the most common causes:
| Reason | Solution |
|---|---|
| Circuit breaker is off | Turn on the circuit breaker |
| Bad extension cord | Try a different cord |
| Malfunctioning device | Test devices individually |
Reason 1: Circuit Breaker Is Off
The most common cause of no output is a tripped circuit breaker.
Solution:
The circuit breakers on the DuroMax XP12000EH are located on the front power panel’s right side. Flip the levers up to turn them on. If they keep tripping, you’re likely overloading the generator.
Reason 2: Bad Extension Cord
A faulty extension cord can prevent power from reaching your devices.
Solution:
Try a different extension cord. If everything works with the new cord, the original was faulty. For generators this size, use a heavy-duty 10-gauge cord for runs over 50 feet.
Reason 3: Malfunctioning Connected Device
Sometimes the issue is the device you’re trying to power, not the generator.
Solution:
Disconnect all devices and test them one at a time. If a specific device doesn’t work, the problem is with that device, not your generator.
DuroMax XP12000EH Does Not Support Connected Devices
If the generator runs but can’t power your devices properly, check these causes:
| Reason | Solution |
|---|---|
| Generator is overloaded | Reduce the load |
| Air filter is dirty | Clean or replace the filter |
| Voltage fluctuation | Check for surging issues |
Reason 1: Generator Is Overloaded
The XP12000EH has 12,000 starting watts and 9,500 running watts. If you exceed this, the generator will struggle or shut down.
Solution:
Remove some devices. Check out what a 12,000 watt generator can run to plan your load properly. Remember that starting watts for motors are 2-3x higher than running watts.
Reason 2: Air Filter Is Dirty
A clogged air filter restricts airflow and reduces engine performance.
Solution:
Remove and inspect the air filter. If it’s dirty, wash the foam element with soapy water and let it dry completely. For a paper filter, tap it gently to remove dust or replace it with a new air filter.
DuroMax XP12000EH Dual Fuel Troubleshooting
The XP12000EH is a dual fuel generator that runs on both gasoline and propane. Here are common issues specific to dual fuel operation:
| Problem | Cause | Solution |
|---|---|---|
| Won’t start on propane | Fuel selector in wrong position | Turn selector to propane position |
| Propane tank connected but no fuel | Tank valve closed | Open the propane tank valve fully |
| Runs rough on propane | Low propane pressure | Check regulator, ensure tank is >20% full |
| Less power on propane | Normal – propane has less BTU | Expect 10-15% less power on propane |
| Won’t switch fuels while running | Normal safety feature | Stop engine, switch fuel, restart |
Starting on Propane
- Connect the propane tank using the included hose
- Open the propane tank valve fully
- Turn the fuel selector switch to “Propane/LPG”
- Set the choke to closed (for cold start)
- Turn engine switch to “Run”
- Pull the recoil starter or use electric start
Switching Between Fuels
Never switch the fuel selector while the engine is running. Always:
- Turn off the generator
- Wait for the engine to stop completely
- Switch the fuel selector to your desired fuel
- Restart the generator
Propane vs Gasoline: What to Know
- Power: Propane produces about 10-15% less power than gasoline
- Runtime: A 20lb propane tank gives roughly 8-10 hours at 50% load
- Storage: Propane stores indefinitely, gasoline degrades after 30 days
- Maintenance: Propane burns cleaner, leading to less carbon buildup
If your generator starts then dies, the issue is often fuel-related. Check out our dedicated troubleshooting guide for that specific problem.
Conclusion
The DuroMax XP12000EH is a reliable dual fuel generator, but like any machine, it needs regular maintenance and occasional troubleshooting. Most problems come down to the basics: fuel, oil, spark, and air.
If you’ve tried these troubleshooting steps and your generator still isn’t working properly, it may be time to consult a professional or contact DuroMax customer support.
For more generator troubleshooting guides, check out our articles on generator surging, overloaded generators, and Westinghouse troubleshooting.
Frequently Asked Questions (FAQs)
What type of oil should I use in my DuroMax XP12000EH?
DuroMax recommends SAE 10W-30 oil for most conditions. In temperatures consistently below 32°F (0°C), you can use 5W-30. Always use oil rated for 4-stroke engines. The XP12000EH holds approximately 1.16 quarts (1.1 liters) of oil.
How often should I change the oil in my DuroMax generator?
Change the oil after the first 20 hours of use on a new generator, then every 50 hours or at least once per season. If you use the generator frequently during emergencies, check the oil before each use and change it if it appears dark or contaminated.
Can I run my DuroMax XP12000EH on propane only?
Yes, the XP12000EH can run exclusively on propane. However, note that propane produces about 10-15% less power than gasoline. On propane, expect around 10,800 starting watts and 8,550 running watts instead of the full 12,000/9,500 on gasoline.
Why does my DuroMax generator surge or hunt?
Surging is usually caused by a dirty air filter, old fuel, or a clogged carburetor. Clean or replace the air filter, drain old fuel and add fresh gasoline with fuel stabilizer, and clean the carburetor if needed. If surging persists, the carburetor may need professional cleaning or adjustment.
How long will a 20lb propane tank run my DuroMax XP12000EH?
A standard 20lb propane tank will run the XP12000EH for approximately 8-10 hours at 50% load. At full load, expect around 4-5 hours. Runtime varies based on load and ambient temperature. Keep a spare tank on hand during extended outages.
Where is the best place to store my DuroMax generator?
Store your generator in a dry, covered area like a garage or shed. Keep it away from excessive dust and moisture. If storing outdoors, use a quality generator cover. Before long-term storage, run the carburetor dry or add fuel stabilizer to prevent fuel system problems.
What spark plug does the DuroMax XP12000EH use?
The DuroMax XP12000EH uses an F7RTC or equivalent spark plug. The gap should be set to 0.028-0.031 inches (0.7-0.8mm). Check and clean the spark plug every 50 hours of use, and replace it annually or if you notice starting problems.
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duromax 12000 hx just bought last month nov 2023 using propane only finally cranked once after backfire several times will not crank now . Engine turns over fine but only backfires Never put in gasoline only propane 0 hours chris lea 662 230 0299
I’m sorry to hear that your new Duromax 12000 HX is giving you trouble, especially so soon after purchasing it. Since the engine is turning over but only backfiring and not starting, it might be an issue with the fuel mix or ignition.
Here’s what you can try:
1. Check the Propane Supply: Make sure your propane tank is full and the connections are secure. Sometimes a low propane level or loose connection can cause issues.
2. Inspect the Spark Plug: A faulty or dirty spark plug can cause backfiring. It might be worth checking or replacing the spark plug to see if that helps.
3. Consult the Manual: Double-check the user manual for any troubleshooting tips specific to your model.
4. Contact Support: Since it’s a new unit, I’d recommend reaching out to Duromax customer support. They should be able to guide you through a solution or arrange for a technician to take a look.
If none of this works, it’s best to get professional help to avoid damaging the generator. I hope you get it up and running soon!