If you've been running your V-twin hard lately, you've probably realized a predator 670 fuel pump upgrade is one of the first things you actually need to do to keep that engine happy. These 22HP engines are absolute workhorses for the price, but the stock fuel delivery system is—to put it politely—a bit of a weak link. Whether you've swapped this engine into a golf cart, a mud motor, or a garden tractor, the factory pulse pump often struggles to keep up when you're pushing the throttle.
It's frustrating when you're out there working or playing and the engine starts to cough or lose power just as things are getting good. Usually, that's not a carb issue or a spark issue; it's just the engine starving for gas. Let's get into why the stock setup fails and how you can fix it without spending a fortune.
The Problem with the Stock Pulse Pump
The Predator 670 comes from the factory with a standard vacuum-operated pulse pump. Now, in a perfect world, these are great because they're simple. They use the pulsing pressure from the crankcase to move a little rubber diaphragm back and forth, which pulls fuel from your tank and pushes it into the carburetor.
But here's the reality: those stock pumps are made of thin plastic and use pretty cheap internals. Over time, the heat from the engine bay makes that plastic brittle. Even worse, the diaphragm inside can stretch or pinhole. If you're running fuel with ethanol in it—which most of us are unless we're lucky enough to live near a marina—that ethanol eats away at the rubber. Before you know it, the pump is barely moving any fuel at all.
Another huge issue is mounting location. If your fuel tank is sitting lower than the engine, that little pulse pump has to work twice as hard to "lift" the fuel up. On a lot of custom builds, the tank is a foot or two away, and the stock pump just doesn't have the vacuum strength to pull fuel consistently, especially at high RPMs. That's when you get that annoying surging feeling.
Choosing the Right Upgrade
When you decide to go through with a predator 670 fuel pump upgrade, you basically have two paths you can take. You can either go with a high-quality name-brand pulse pump or make the jump to an electric setup.
High-Flow Pulse Pumps
If you want to keep things simple and avoid messing with your electrical system, a Mikuni high-flow pulse pump is the way to go. These are legendary in the small engine world. They're built with much better materials and can move significantly more CCs of fuel per hour than the generic one that comes on the Predator.
The beauty of a Mikuni is that it's a direct "bolt-on" in terms of how it functions. You still use your existing vacuum line from the crankcase. It's a "set it and forget it" kind of deal. For most people doing light off-roading or yard work, this is more than enough to solve the starvation issues.
The Electric Route
Now, if you really want to do it right—especially for racing or heavy-duty use—going electric is a total game-changer. A small 12V low-pressure electric fuel pump ensures that the carburetor always has a steady supply of fuel, regardless of what the engine's vacuum is doing.
When you turn the key, the pump primes the carb instantly. You won't have to crank the engine over for ten seconds just to get gas into the bowl after the tool has been sitting for a week. However, you have to be careful here. The Predator 670 carb doesn't like a lot of pressure. You want a pump that puts out about 1 to 3 PSI max. If you throw a 5 or 7 PSI pump on there, you're going to blow right past the needle and seat in the carb and flood the engine.
Step-by-Step Installation Tips
Actually doing the predator 670 fuel pump upgrade isn't rocket science, but there are a few "gotchas" that can trip you up if you aren't looking for them.
First, if you're switching to electric, you'll need to block off the pulse port on the engine. This is the little nipple where the vacuum hose used to go. You can't just leave it open, or you'll have a massive vacuum leak and the engine will run like garbage. Most guys just use a short piece of vacuum line with a bolt clamped into the end of it, or a dedicated rubber vacuum cap.
Second, think about where you're mounting the new pump. If you're using a pulse pump, keep it as close to the engine as possible to keep those vacuum pulses strong. If you're going electric, try to mount the pump lower than the fuel tank if you can. Electric pumps are much better at "pushing" fuel than "pulling" it.
Don't forget the wiring if you go the electric route. You should tap into a keyed power source. You definitely don't want the pump running 24/7 when the engine is off, or you'll end up with a dead battery and potentially a crankcase full of gasoline if the needle valve leaks. Using a simple 4-pin relay is the professional way to do it, but at the very least, make sure it's on a fused circuit.
Don't Forget the Lines and Filters
While you're messing with the predator 670 fuel pump upgrade, do yourself a favor and toss those cheap, stiff factory fuel lines. They tend to crack and leak air, which creates bubbles in the system.
Pick up some high-quality 1/4-inch automotive-grade fuel line. It stays flexible and seals much better around the barbs. Also, grab a clear, decent-sized fuel filter. Being able to see the fuel flowing is a lifesaver when you're trying to troubleshoot why the engine won't start six months from now. If the filter is empty, you know exactly where to look.
I also highly recommend using actual hose clamps. Those little spring clips that come from the factory are okay, but they lose their tension over time. A small worm-gear clamp or a fuel injection style clamp ensures you won't have any "surprise" fires while you're out in the woods.
What to Expect After the Upgrade
Once you get everything hooked up and leak-tested, you're going to notice a difference almost immediately. The most obvious change is the starting. With a consistent fuel supply, the Predator 670 usually fires right up on the first or second rotation.
But the real magic happens under load. When you're climbing a hill or pulling a heavy load, and that governor opens up the throttle, the engine won't stumble anymore. It stays crisp. You'll find that the "top end" feels a lot more solid because the fuel bowls stay full even when the engine is screaming.
Honestly, for the thirty or forty bucks it costs to do this right, it's arguably the best bang-for-your-buck mod you can do. It takes the engine from being a "cheap clone" that's a bit finicky to a reliable power plant that you can actually trust.
Final Thoughts on Fuel Delivery
Building a custom rig is all about reliability. There's nothing worse than having a 670cc V-twin that sounds like a beast but runs like a lawnmower because it can't get enough juice. Whether you choose a beefier pulse pump or a dedicated electric setup, the predator 670 fuel pump upgrade is one of those tasks you'll be glad you checked off the list.
It's one of those "garage weekend" projects that pays off every single time you turn the key. Just take your time with the routing, make sure your connections are tight, and keep that fuel pressure low. Your Predator will thank you for it by running smoother than it ever has. Happy wrenching!