For most gas-powered jobs, the GMAX II 5900 (200cc Honda, up to 2.35 GPM at 3300 PSI) covers single-gun work with long hose runs. Step up to the GMAX II 7900 (35% more output) for multi-gun setups or heavier coatings. For the thickest materials — block-fillers, fireproofing, roof mastics — the DutyMax GH300 (up to 3.0 GPM, electric-hydraulic) outperforms both. The DutyMax GH230 sits between the GMAX line and the GH300 for heavy-duty hydraulic applications on a Honda GX270 platform.
Gas-powered Graco sprayers exist to solve one specific problem: electric rigs losing pressure over long hose runs, struggling with multi-gun setups, or simply not having the flow rate for thick coatings. But "gas-powered" covers a wide spread of machines, from the 200cc GMAX II 5900 to the 3.0 GPM DutyMax GH300. Picking the wrong one means either overpaying for capacity you don't need, or running a machine that can't keep up with the coating in front of it.
1. Why Go Gas-Powered at All
Contractors tackling block-fill, intumescent fireproofing, or stadium-wide striping can't risk voltage drops or limited flow. A gas-powered sprayer couples a fuel-driven engine to a heavy-duty piston or hydraulic pump, delivering consistent pressure regardless of hose length or the number of guns running off the same machine — something electric rigs start to struggle with past a certain distance.
2. GMAX II 5900 vs. 7900
GMAX II 5900
200cc Honda-powered engine, up to 2.35 GPM at 3300 PSI. A single 5900 can feed two 0.027-in tips up to 200 ft from the machine — Graco's benchmark for portable productivity.
GMAX II 7900
Roughly 35% more performance than the 5900. Handles the widest range of tip sizes, multiple guns, longer hose lengths, and heavier coatings — Graco's largest gas mechanical sprayer.
The 7900 pushes larger 0.041-in orifices without starving the fan pattern, which is the practical difference that matters on site: the 5900 covers most single-gun, long-run jobs comfortably, while the 7900 is built for when a crew needs multiple guns working simultaneously.
3. DutyMax GH230 vs. GH300
DutyMax GH230
Honda GX270 9HP engine driving a hydraulic pump into an Endurance MAXLIFE fluid section. A long-stroke, direct-immersion pump built for plasters, elastomerics, fire retardants, and liquid roofing.
DutyMax GH300
Graco's electric-hydraulic powerhouse: up to 3.0 GPM at 3300 PSI. Pumps block-fillers, intumescent fireproofing, and fibered roof mastics all day, powered by a closed-loop hydraulic circuit with a 25-micron spin-on filter.
The GH300's output depends entirely on a closed-loop hydraulic circuit. A cracked reservoir cap or a clogged filter can seize the entire system within minutes — keeping the hydraulic seal set (248977) and filter (246173) on hand as spares is genuinely cheap insurance against a job-site shutdown.
4. Full Spec Comparison
| Model | Flow Rate | Max Pressure | Power Source |
|---|---|---|---|
| GMAX II 5900 | Up to 2.35 GPM | 3300 PSI | 200cc Honda engine (mechanical) |
| GMAX II 7900 | ~35% more than 5900 | 3300 PSI | Honda engine (mechanical) |
| DutyMax GH230 | Model-dependent, heavy-duty hydraulic | 3300 PSI | Honda GX270 9HP (hydraulic) |
| DutyMax GH300 | Up to 3.0 GPM | 3300 PSI | Electric-hydraulic (Honda GX390 variant available) |
5. Shared Parts Across the Line
- GH230 and GH300 share an identical GX270 governor and recoil assembly — a real opportunity to consolidate spares across a mixed fleet.
- GH230 and GMAX 7900 share the same coupling and air filter element, despite being different pump architectures (hydraulic vs. mechanical).
- DutyMax GH300 and Ultra Max II 695 ProContractor use the same RAC X guard and 60-mesh filter — handy for shops running both a gas rig and an electric contractor machine.
- Displacement pump wear parts — wiper rod (117739), bearing and rod (112342), packing O-ring (117283) — apply across the GH130/200/230/300 pump family.
6. Matching the Machine to the Job
- Single gun, long hose run, standard coatings — GMAX II 5900 covers this comfortably.
- Multiple guns or heavier coatings — step up to the GMAX II 7900 for the added flow and wider tip range.
- Plasters, elastomerics, fire retardants, liquid roofing — DutyMax GH230's hydraulic pump is built specifically for this material class.
- Block-fillers, intumescent fireproofing, fibered roof mastics at the highest volume — DutyMax GH300 is the top of the line for these applications.
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Frequently Asked Questions
What's the flow rate difference between the GMAX II 5900 and 7900?
The 7900 delivers roughly 35% more performance than the 5900, handling up to 2.35 GPM at 3300 PSI. The 5900 covers most single-gun, long-hose-run jobs; the 7900 fits multi-gun setups and heavier coatings.
How does the DutyMax GH300 compare to the GMAX II line?
The GH300 is Graco's electric-hydraulic powerhouse, delivering up to 3.0 GPM at 3300 PSI — higher flow than either GMAX II model, built specifically for block-fillers, intumescent fireproofing, and fibered roof mastics.
Do the DutyMax GH230 and GH300 share engine parts?
Yes — both use a Honda GX270 governor and recoil assembly, and several engine components interchange across the DutyMax line and even with certain GMAX 7900 and LineLazer components.
When does a gas-powered sprayer make more sense than electric?
When the job involves long hose runs, multi-gun setups, or thick materials like elastomeric coatings, fireproofing, or roof mastics — situations where electric rigs are prone to voltage-related pressure drop.