My milage has been dropping and is now down to around 16 mpg mixed city / highway. I am due a fuel filter change and plan to do that this coming weekend. I have seen several post saying that will help so I am going to do it as I have 25k miles (or more) on the current filter.

My question is, can someone explain how a clean fuel filter improves milage?

Thanks.

 

a clean fuel filter has less drag/friction the a dirty one. based on this principle when ur dirty the engine has to work harder and u lose MPGs

 

You also lose fuel pressure which causes a poor spray pattern from the injectors. The fuel doesn't burn as efficiently.

 

Got it. Thanks for the replys.

 

I try to go about half that interval... the thing is cheap, and once you learn the tricks, it can be changed painlessly.

 

I've heard a few guys say they adamantly chage it every season-4x a yr.

 

Can you elaborate on the tricks please?? I can hardly even see my fuel filter on my 97.. Thanks

 

You have an auto, so it will likely be bulkier, and you may not be able to snake the filter down beside the transmission like I do, but...

First off, wear disposable gloves - if diesel gets on them, change them not long after, it will destroy the material. It is worth using the gloves. Very much so.

-> Get a 750 mL (~16 oz) yoghurt container, put the filter drain tube into it /so the fuel drains into it, and squeeze it up in/on the front axle diff. If that doesn't work, well, it does on my truck.

-> Open the water drain valve and let it run until it stops running, the yoghurt container should be almost full, but you'd be well advised to keep an eye on it. There is about 700 mL I'd guess in the fuel filter canister, so you'll get most of it.

-> Close the valve, pull the yoghurt container out, dispose of the fuel safely.

-> Unclip WIF sensor, loosen the filtre canister, remove, rotate, and place on the frame rail.

-> Go below the truck, remove it by gently guiding it along beside the engine/transmission and frame

-> pull out the old filtre and seals, clean well

-> fill it 85% full with fuel ideally sparkling clean, but if you do it this way, it should go in the dirty side of the filtre, so it won't be a big concern if the fuel is ordinary grade. It will be about 90% full now.

-> (NEED GLOVES FOR THIS) Lube rubber seals/o-rings with diesel fuel. Now put the new filtre in - slowly, let the fuel go through the filtre material so it doesn't spill.

-> Put a small bag that covers the whole top of the filtre assembly on top of this. The bag is to prevent crud from falling into the filtre as you place it in the truck.

-> go underneath the truck, and very carefully and slowly raise the filtre to the point on the frame where you stored the canister before.

-> go to top of truck. VERY CAREFULLY remove bag so no crud gets on the filtre (the clean side is exposed!). Immediately install canister, it will fit only in one position due to notch, and tighten nut that holds it. Reclip WIF sensor.

-> I don't re-prime the system. I've found I can fill the fuel canister sufficiently that the engine will only run rough for a handful of seconds.

-> Rejoice in having changed the filtre without getting any diesel on yourself.

If you do this properly, and filled it enough, you do not need to bleed your fuel system. My engine runs rough with a small amount of throttle for about 10-15 seconds at most, then runs smooth as silk. I can do this without any spillage. Though my narrow, lanky arms probably help.

 

Thanks much for a very detailed explanation..

 

The above instructions are all good. The only key words that can be very hard are "loosen the filter canister". That part can be a real PITA. You can't (or at least I can't) reach it from the bottom and I can't get a good grip from the top. Even though you put the filter on "hand tight", it takes more effort than "hand loosen" after time and heat have take their toll. I have a dedicated 15" screwdriver that I hammer into the upper edge or lip of the canister. You have to be careful, use the edge of the blade, and be careful to not damage the housing. The screwdriver will notch the canister and you can hammer it a 1/4 turn or so, then I can use my hands. Just personal preference, but I do all the work from the topside, I don't go under except to drain the filter.

 

Baja, those instructions are only useful for the 97 up cannister style.

You got lucky and still have the spin on one.......

 

There is only one "dumb question" and that is the one not asked...

Hope this helps on filter replacement, it's not the cleanest job on one of these. I have seen a system installed that moves the filter up close to he battery, not sure what it is - it nearly covers the injection pump.