I changed my fuel filter for the first time.

I have a 2004 Toyota Tazz 1300. I have installed my new fuel filter. Here it is:

Engine compartment showing fuel filter on firewall

And this is my fuel filter zoomed in:

Detail of fuel filter

I have assumed that the tube on the left going down comes from the fuel tank, and the right hand tube over the top goes to the engine. Is this correct?

I ask, and am second guessing myself, because the previous fuel filter was installed opposite to this (the in arrow connected to the top tube, and the out arrow connected to the one going down). Is it safe to assume that the one on top is the engine one, or is there something here I am missing and it should be the other way around?

  • 1
    Not a "noob" question at all. It's smart to be making sure that you understand what you're doing and how the pieces fit together.
    – dlu
    Commented Oct 1, 2016 at 16:53

2 Answers 2


Follow the fuel lines carefully. It appears that the route of the fuel lines and fuel flow goes:

  1. From the tank to the fuel pump on the engine in the upper hose to the pump that appears to come from under the firewall, then
  2. To the fuel filter in the lower hose from the pump to the right hand side of the fuel filter, then
  3. Thru the filter and out on the left hand side to the short black hose that heads down.

The big question is "where does the short black hose go?" If it leads to the engine, then I'm right and the fuel inlet of the filter should be connected to the long black hose and the outlet should go to the short hose, but if that short hose leads under the vehicle and back to the fuel tank then it is more of a mystery and you'd want to track the upper hose on the fuel pump that appears to also head towards the back of the car. One of those two should lead to the fuel distribution system on the engine. The one that does should be attached to the outlet side of the filter.

  • Thanks for your answer. I'm not 100% clear where the fuel pump is, could you point it out? I'll take a look again tomorrow when I get the chance and see if I can follow the short black hose goes.
    – user17336
    Commented Oct 1, 2016 at 18:21
  • Sorry about that, in your photo, the fuel pump is the gray/silver device on the engine that is connected to the hose that comes from the right side of the fuel filter. The other hose on the pump appears to go towards the firewall and the down towards the back of the car (where it might connect to the fuel tank).
    – dlu
    Commented Oct 1, 2016 at 18:40
  • I should add, that I'm assuming that that is the (or a) fuel pump. I'm not that familiar with Toyotas of that vintage, but it sure looks like one. If it is the pump it will either be connected to the engine (so that the engine can drive it) or there will be an electrical connection to power it. Otherwise it's something else (maybe a fuel pressure regulator?).
    – dlu
    Commented Oct 1, 2016 at 18:42

From the first picture it appears you have it attached correctly. The one coming up from the side and below would be from the tank. The other one is headed to the engine. Looks like you're golden.

  • Thanks! I feel quite silly asking because it seems pretty obvious which one goes to the engine - the old filter being backwards really threw me off. Now I'm concerned that I've been driving around with a backwards filter for the last few months!
    – user17336
    Commented Oct 1, 2016 at 13:12
  • @stanri - Can I please have you trace the lines ... I was looking at the image on my phone and now I'm looking at it on my computer and I may have given you bad advice. I cannot tell which way anything is going as there are a lot of connections and directions there. If you follow the right hand hose (from the fuel filter), back to the metal fixture on the engine, then back down to the side, then around to the orange "thing" ... where does it go from there? It could have been right in the first place. Commented Oct 1, 2016 at 14:53
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    You could always "test" how it flows. Take both connections off at the fuel filter. Place both into a catch container, then have someone turn the ignition on for a short moment. Which ever the fuel comes out of is definitely the one coming from the fuel pump. Commented Oct 1, 2016 at 14:54
  • Are you talking about the line that goes through the orange cylinder on the right? I traced it to that but haven't looked beyond it yet. I'll take a look again tomorrow. What is the metal fixture on the engine for? It also has a line off to the left, which leads to below (what I think is) the air filter.
    – user17336
    Commented Oct 1, 2016 at 18:24
  • I think the metal part is a fuel pressure regulator, but not sure. Commented Oct 1, 2016 at 19:00

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