Anybody know anything about the fuel filter?

steinwayb

Member
When my Mazda5 hit the 30k mile mark, the dealer tried to sell me their 30k mile service. I had read the manual prior to this and realized that a lot of the stuff he was planning on doing wasn't listed in the manual. One of the things he wanted to do was replace the fuel filter. When I told him the manual does not mention this, he sheepishly said that I was right. Then he said something strange, something like the Mazda5 does not have a fuel filter, or, to replace it, you have to remove the gas tank. Does anyone have any idea if the Mazda5 has a replaceable fuel filter, and if so, where it is located? I have never heard of a car that did not have a replaceable fuel filter, but I've looked under the hood and under the car and cannot locate anything that looks like a fuel filter. The dealer's comment about removing the gas tank sounded like maybe it has some type of non-replaceable filter designed to last the life of the car, but I really have no idea. Any help would be appreciated.
 
Huh...guess it could be inside the tank with the pump but most modern cars have the fuel filter under the chassis back near the fuel tank. Let us know what you find.
 
The dealer is correct. There are actually 2 inside the tank.
 

Attachments

  • Fuel Filter.jpg
    Fuel Filter.jpg
    56.4 KB · Views: 10,208
Wow...that is super lame of Mazda to not make the one easy to change. Thanks for the info.

They're all starting to do that crap now. My Focus is the same way. Ford calls it a "lifetime fuel filter" like it's a good thing. What a load of crap. Basically, what this tells you is that the fuel pump is crap and they know you'll need to get into the gas tank before the filter is bad anyway. So they market building cheaper, crappier parts as a benefit to you. Shameless.
 
unless you guys are dumping a load of top soil down your fuel cap, chances are you will never need to change out your fuel filter. have you even opened up your tank to see what it looks like in there? i have. and after 165,000 miles, the inside of my fuel tank still looked new.
 
I agree Nik.

If you've ever replaced a fuel pump, you'll know that they have fine sediment screens on them already. This is probably what the manual refers to as the low pressure filter. On a 16 yo pickup, the tank had virtually no sediment. I'm pretty confident that the fuel filters will be fine.

Still, I always bypass the gas station that has a tanker truck refilling it as I was taught the sediment is sturred up as they dump new fuel in. Why chance it?
 
I agree Nik.

If you've ever replaced a fuel pump, you'll know that they have fine sediment screens on them already. This is probably what the manual refers to as the low pressure filter. On a 16 yo pickup, the tank had virtually no sediment. I'm pretty confident that the fuel filters will be fine.

Still, I always bypass the gas station that has a tanker truck refilling it as I was taught the sediment is sturred up as they dump new fuel in. Why chance it?

i would even question this as fact or myth. with the strict fedral regulations on fuel emmissions, i would think that those tanks are tightly sealed to prevent sediment.
 
Sure, they are sealed, but that doesn't mean when the covers are removed that dirt doesn't drop right in.
 
Here is the text from a couple of pages after flcruising's attachment. In a nutshell there is a fuel pump unit which includes the fuel pump, both the low and high pressure filters, and the pressure regulator. The reason why the filters were included with the fuel pump was to “simplify the fuel line”, and the reason why the pressure regulator is included is because of the “returnless fuel system”.

The "good" news is that while the unit is in the gas tank, there are quick connectors to easily get to the pump. The days of having gasoline dumped on your arm as you take off the fuel filter are over, as are the days of cheap fuel filters.

To give you an idea of the price, MSRP of this fuel pump unit is US$241.85 though you can buy it for US$188.60 at Montogomery Mazda, probably a similar price at Med Center Mazda.

RETURNLESS FUEL SYSTEM OUTLINE
Features
• The returnless fuel system reduces fuel evaporation in the fuel tank.
• The pressure regulator located in the fuel tank prevents fuel return from the engine compartment side, thereby maintaining a low fuel temperature in the fuel tank. Due to this, formation of evaporative gas produced by a rise in fuel temperature is suppressed.
• The pressure regulator is built into the fuel pump unit in the fuel tank.

RETURNLESS FUEL SYSTEM OPERATION
• Fuel in the fuel tank is pumped out through the fuel filter (low-pressure) by the fuel pump, filtered by the fuel filter (high-pressure), and then regulated to a specified pressure by the pressure regulator.
• The pressure regulated fuel is sent to the fuel injectors.
• After pressure regulation, unnecessary fuel is returned from the pressure regulator to inside the fuel pump unit.

and a couple pages later:

Fuel Pump Unit
• Mainly consists of a fuel filter (high-pressure), pressure regulator, fuel pump, fuel reserve cup, and fuel filter (low-pressure).
• A pressure regulator is built-in due to the adoption of a returnless fuel system.
A hard-plastic fuel pump unit, with an integrated fuel filter (high-pressure) and fuel pump, has been adopted to simplify the fuel line.
• Fuel in the fuel reserve cup is suctioned out through the fuel filter (low-pressure) by the fuel pump, and pumped to the fuel filter (high-pressure). Return fuel is sent back to the fuel reserve cup or the fuel tank through the jet pump.
• If return fuel pressure exceeds the specified value, the relief valve discharges return fuel into the fuel pump unit without passing it through the venturi. Due to this, return fuel pressure is maintained below the specified value.

Pressure Regulator
Built into the fuel pump unit due to adoption of a returnless fuel system.
• Mainly consists of a spring, release valve and diaphragm.
• Pressurizes fuel discharged by the fuel pump to approx. 390 kPa {3.98 kgf/cm2, 56.6 psi} using the spring, diaphragm and release valve, and then pumps it to the fuel distributor.
• If fuel pressure exceeds approx. 390 kPa {3.98 kgf/cm2, 56.6 psi}, the release valve opens to discharge unnecessary fuel pressure.
 
Last edited:
unless you guys are dumping a load of top soil down your fuel cap, chances are you will never need to change out your fuel filter. have you even opened up your tank to see what it looks like in there? i have. and after 165,000 miles, the inside of my fuel tank still looked new.

Have you ever changed a fuel filter on a car? I've changed filters on fuel injected and carburated cars (where you actually see the filter element instead of it being sealed in a canister like a FI car). There is a disgusting amount of crap that gets into these things.
 
^ I've changed enough to know it was my least favorite 'maintenance' item. Since they aren't like oil filters catching lots of particles, they don't really have to be changed unless they are seriously restricting the flow. Have you ever waited that long before changing your fuel filter? I haven't, but apparently it's not a regular maintenance item in Mazda's eyes, so unless my experience is otherwise, I won't lose any sleep about it.

My daily driver has an internal 'lifetime' transmission filter that would require pulling the transmission just to change it. I've had no problems with it in over 200k miles, so I'm not too worried about the lack of servicability.
 
Thanks for all the info

Just checking back in and see that there has been a lot of activity on my post. Thanks to everyone for providing this info and clearing this up for me. I fall into the camp that this is "hopefully" an improvement and one less thing to worry about. Only time will tell....but it still burns me that the Mazda dealer handed me a pre-printed glossy page showing all the things that they do at 30k service, and included the fuel filter change on it. I think his original price was somewhere near $350, but I ended up paying about $100 for whatever it was I agreed to (can't recall right now what exactly that was). Thanks again to everyone!
 
so im guessing, just get to the pump take it out and replace it with the attached filter/mesh and thats it? what about fuel pressure? (not a mechanic btw, just DIY wanna be lol)
 
i was just wondering in case fuel would spray when disconnecting the fuel lines which i seen now n dont seem so simple to disconnect, for pressurized fuel you can just open the gas tank or take your fuel pump fuse out n try to start the car 3 times which it will not since is not getting any fuel without the fuse
 
If your car sits overnight, there rarely is any residual fuel pressure as it depressurizes naturally. Opening the gas tank does nothing for the lines themselves. Most vehicles have a service port on/around the fuel rail that you can open to let off the pressure into a cup. Fuel lines don't flex, so you won't get much more than a quick burst when you disconnect them. Don't be too concerned about this, as it's not like a waterhose that can hold a good quantity of pressure behind a nozzle after you've shut off the water. I'm just saying that it's not as big a deal as some make it seem.
 
Please clarify what you mean by plugs...

Are you asking how to disconnect the fuel pump assembly from the hard lines? If so, those lines have disconnects that may require a special too to seperate. I've not done this on the Mazda before, just 3 Chevys. Those could be disconnected by simply squeezing a couple of tabs with either the fingers or some needlenose. Might have taken a small flathead to get one of them off. Either way, I'm not positive about the Mazda, but I'd imagine it couldn't be too different. Autozone may have a loaner tool for it.
 
yeah i meant the hard lines on the outside, n yeah you r right, ill check for the loaner tool, thanks man, great help
 
Back