If your UTV is sputtering or refusing to start, you might be dealing with a bad 2007 yamaha rhino 660 fuel pump. It's one of those parts that you don't think about until it stops working right in the middle of a trail ride, leaving you stranded and wondering why your reliable machine suddenly decided to quit. The Rhino 660 is a legendary workhorse, but like any machine that's been around for over fifteen years, the fuel system is bound to need some love eventually.
The fuel system on the 2007 Rhino 660 is a bit different from what you might find on a modern car or even a newer EFI (Electronic Fuel Injection) side-by-side. Instead of an electric pump that kicks on the second you turn the key, the stock setup uses a vacuum-operated pulse pump. It's a simple design, but it's also prone to a few specific headaches that can make your life difficult if you don't know what to look for.
How the vacuum pump actually works
The 2007 yamaha rhino 660 fuel pump relies on the pulses created by the engine's crankcase. As the pistons move, they create changes in air pressure. This pressure "pulses" through a vacuum line connected to the pump, which moves a little diaphragm inside. That diaphragm acts like a heartbeat, sucking fuel from the tank and pushing it into the carburetor.
When everything is working perfectly, it's a great system because it doesn't require any electrical wiring. However, because it relies on physics and air pressure, it's very sensitive to leaks. If your vacuum line has a tiny crack or if the rubber diaphragm inside the pump gets stiff or torn, the whole thing just stops working. This is usually why these machines are so hard to start after they've been sitting for a few weeks—the fuel in the carb evaporates, and the pump doesn't have enough "oomph" to pull fresh gas from the tank while you're just cranking the starter.
Signs your fuel pump is giving up
You'll usually get a few warning signs before the pump dies completely. One of the most common symptoms is surging or bogging when you're pinned at wide-open throttle. If you're flying down a flat stretch and the engine feels like it's hitting a wall or gasping for air, it's likely because the fuel pump can't keep up with the demand. The carburetor is running out of gas faster than the pump can replenish it.
Another big red flag is backfiring. If the engine is leaning out because it's not getting enough fuel, it'll run hot and pop when you let off the gas. And, of course, there's the classic "hard start" issue. If you find yourself cranking the engine for thirty seconds and smelling no gas at all, that 2007 yamaha rhino 660 fuel pump probably isn't doing its job.
The debate: OEM vacuum vs. electric conversion
When it comes time to replace the pump, you've got a choice to make. Do you stick with the original vacuum style, or do you upgrade to an electric setup? A lot of guys in the Rhino community swear by the electric conversion. An electric pump provides a consistent flow of fuel as soon as the ignition is on, which pretty much eliminates the hard-starting issues these 660s are famous for.
That said, an electric pump isn't a "plug and play" fix for everyone. You have to be careful about the pressure. The Rhino's carburetor is designed for a very low-pressure feed. If you throw a high-pressure automotive fuel pump on there, you'll blow right past the needle and seat in the carb and flood the engine. If you go electric, you need a pump that puts out about 1.5 to 3 PSI max, or you'll need to install a pressure regulator.
On the other hand, sticking with a high-quality vacuum-style 2007 yamaha rhino 660 fuel pump is much simpler. You don't have to mess with wiring or find a keyed power source. If you go this route, I'd suggest avoiding the dirt-cheap "no-name" pumps you see online for ten bucks. They often have thin diaphragms that won't last a season. Spending a little more on a Mikuni or a reputable aftermarket brand will save you a lot of frustration down the road.
Troubleshooting before you buy parts
Before you go out and buy a new pump, do yourself a favor and check the lines. The fuel lines on a 2007 model are old. They get brittle, they crack, and they can even collapse internally. Check the vacuum line that runs from the engine to the pump specifically. If that line has a crack, the pump won't get the signal it needs to move fuel.
Also, take a look at your fuel filter. A clogged filter will mimic the symptoms of a bad 2007 yamaha rhino 660 fuel pump perfectly. If the filter is full of silt from the bottom of your gas tank, no pump in the world is going to get enough gas through to keep the engine running smoothly. It's a five-dollar part and worth changing every year anyway.
Tips for a smooth installation
Swapping out the pump is actually pretty easy. It's located under the hood/cowl area, and you don't need any specialized tools. Just a set of pliers for the hose clamps and a screwdriver or socket for the mounting bolts.
One pro tip: mark your hoses. There are usually three lines going to the pump: the "in" from the tank, the "out" to the carb, and the "pulse" line from the engine. If you swap the "in" and "out" lines, the Rhino won't start, and you'll be scratching your head for an hour. Use a piece of masking tape or a Sharpie to label them before you pull the old pump off.
Once you have the new 2007 yamaha rhino 660 fuel pump installed, you might need to prime the system. Since the pump only works when the engine is turning over, it can take a bit of cranking to get the gas from the tank all the way up to the carb. Some people like to use a little shot of starting fluid to get the engine to fire, which then pulses the pump faster and gets the fuel moving. Just don't overdo it with the spray.
Keeping the system healthy
The best way to keep your fuel pump happy is to use good gas and a stabilizer if the Rhino sits for a while. Ethanol is the enemy of these old fuel systems. It eats away at the rubber diaphragms and fuel lines over time. If you can find non-ethanol (recreational) fuel, your Rhino will thank you for it.
In the end, maintaining or replacing your 2007 yamaha rhino 660 fuel pump is just part of the UTV ownership experience. These machines are tough as nails, and once you get the fuel delivery sorted out, they'll keep pulling through the mud and over the rocks for years to come. Whether you stick with the stock vacuum setup or decide to go electric, getting that steady flow of gas back to the engine will make your rides a lot more enjoyable and way less stressful. There's nothing quite like the peace of mind that comes with knowing your machine is going to start right up every time you hit the key.