What is a fuel filter? How do fuel filters work? Fuel filters protect your vehicle’s fuel system by removing contaminants such as rust, dirt and other foreign matter from the fuel. Stricter emissions legislation, higher injection pressures and ultra-low sulfur and biodiesel fuels have all contributed to the evolution of fuel system technology. However, the fuel filter is often overlooked in terms of regular maintenance.
Video transcript: How to Change a Fuel Filter
Featuring John Gardner, ASE Master Certified technician, automotive technology instructor and host of Motorhead Garage, with AMSOIL Director of Product Marketing Len Groom (author profile).
John Gardner: Maybe your car is a little sluggish. Maybe it’s hesitating, or you’ve just got bad performance. Perhaps, bang, you’ve got the check engine light on. Well, welcome to this AMSOIL Tech Tip. It might just be as simple as a fuel filter.
What are we talking about when we’re talking about a fuel filter? A filter that filters the fuel. Pretty obvious. But if you look right there at the fuel tank, fuel comes up, goes through the fuel filter and the injectors, and on a lot of systems it returns back to the tank.
How do you change a fuel filter? Great question. A lot of them are in the tank, which may be difficult, but you could also have one right on the frame rail like this. The first step is to disconnect the fuse or the power to the fuel pump and turn the engine over. Why? We’re going to depressurize the system. We don’t want fuel flying. Then get a line wrench and disconnect the fuel filter. Once you’ve got the fuel filter off, make sure your O-rings and everything are in place. When you put the new one on, just reverse the procedure, but make sure you follow the arrow for flow direction. Once you’ve got it on, snug it up, and you’ll be good to go. Some manufacturers recommend about 24,000 miles; look at your manufacturer’s service manual to find out when. Fuel filters can be in the tank, too.
Len, I’ve got a pretty cool demo set up here, if you give me a hand. We’ve got a fuel pump right here, a filter, and then a return. I’ve got a battery down here, so I’m going to reach down and plug it in. And there we go; we’re actually running it. Now I’m measuring the amps, because as the mechanical load goes up, the amp draw is going to go up. What do we have?
Len Groom: 3.7.
John Gardner: 3.7. So what I’ll do is simulate a restriction here. Just like that. Is it going up?
Len Groom: And we are up to 3.9.
John Gardner: 3.9. Yeah. So just think about that for a minute. We’re putting that restriction on that fuel pump, and we’re causing a problem. Now, this came out of a parts washer. This is pretty nasty. But fuel filters have a big job to do.
Len Groom: They do. The fuel filter can get clogged, right? That’s its job: to pick up anything. And this is obviously very dirty fuel, but the fuel filter can get clogged, and if it does, it creates that restriction.
John Gardner: Yeah. And I’ve got a perfect demo for that one. Look at this one right here, and then look at this one. I’ll put them side by side for you guys. What do you think of that one?
Len Groom: Right. A clogged filter generally will collapse, and that’s what you’re seeing. That filter was clogged. It twisted and collapsed. It’s not moving any fuel.
John Gardner: That’s not going to do it. That’s number one. Number two, Len, if you go around the country, there are different fuel blends depending on the climate and the time of year. You may even get some fuel that’s really not up to par. You guys have products that can help with that as well.
Len Groom: We’ve got fuel additives whether you’re dealing with a gasoline vehicle or a diesel vehicle: a full line of fuel additives for all the conditions you described, to cover the seasonality. If you’re operating a diesel in cold temperatures, we’ve got Cold Flow Improver. We’ve got Cetane Boost. We’ve got Octane Boost. Basically, we’ve got additives that can cover all your needs.
John Gardner: Len, here at Motorhead Garage, the crew and I are always preaching maintenance, maintenance, maintenance. Now, I know you believe in that.
Len Groom: Absolutely. And that’s why at AMSOIL we’ve got a full line of maintenance products for your fuel system. So check it out at amsoil.com.
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Joel Youngman is Lead Technical Writer at AMSOIL and associate editor of AMSOIL Magazine. He develops and edits content covering lubricant technology, product testing, vehicle systems, maintenance practices and equipment applications. Youngman also coordinates magazine articles and Tech Talk columns, working with engineers, product specialists and Communications personnel to maintain technical accuracy, editorial consistency and clear customer communication.
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