• From: Flagstaff, AZ
  • Registered: 2020-09-05
  • Posts: 50

Topic: How often do you replace your fuel filter?

In the past we have changed the fuel filter between testing and the race in case it picked up some sludge from sitting.

I was just quoted $50 for a "napa gold" filter! I'm sure I can find one cheaper, but it made me wonder if it's pointless to keep changing the filter every race, which for us is once a year. I put stabil in the gas tank and ran it around the block a few times, but it still has the same gas from the track last year.

Do you think the stabil is good enough to prevent sludge formation, or would you still change the filter before the race, after doing some test laps to slosh everything around?

2 Reply by BigBird (edited by BigBird 2023-04-14 04:16 PM)

  • From: SF BayArea/Land of Enchantment
  • Registered: 2012-01-22
  • Posts: 901

Re: How often do you replace your fuel filter?

I think it all depends on the condition of your fuel tank/system.If your tank is (or was) rusty/chunky,I would think that changing the filter would be cheap insurance against weekend-ruining contamination....I could be wrong,tho.....been wrong before...                                                Edit to add: The StaBil would (hopefully) prevent the sludge,but my comment was geared more toward physical scale,rust,dirt,etc, that would clog up the system and fuck up your day....

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3 Reply by duthehustle93 (edited by duthehustle93 2023-04-14 03:39 PM)

  • From: Camarillo, CA
  • Registered: 2021-03-26
  • Posts: 385

Re: How often do you replace your fuel filter?

We change ours every 100-120 hours with a good condition fuel system (90's CA cars so "newer"). Most cars its a very low frequency maintenance item, but as BigBird pointed out it depends on the condition of the vehicle.

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4 Reply by Camper Van Someren (edited by Camper Van Someren 2023-04-14 05:16 PM)

  • From: Flagstaff, AZ
  • Registered: 2020-09-05
  • Posts: 50

Re: How often do you replace your fuel filter?

Thanks for the responses. The car started out with a sludge filled fuel system but after a tank wash and new fuel pump, then 10+ races I think the original sludge is all gone.

Hopefully the stabil will keep the gas good enough til the next race. Next year I’ll probably do some track days throughout the year to keep everything more fresh.

  • From: NH
  • Registered: 2010-01-20
  • Posts: 3,299

Re: How often do you replace your fuel filter?

If the system is clean, you really don't need to worry. We do nothing to our fuel system when the car sits. No stabil, no additives, no procedure to drain or fill it. Basically the car sits with whatever fuel is in it after a race until the next race. We pulled the fuel cell apart last year for the first time to check everything, and it looked brand new. The foam was perfect, no signs of deterioration. There was nothing in there that would clog the pickups or filter. Every single part honestly looked the same as when I built the fuel cell back in the daytona days. This is after a couple years of doing 1 race a year too, so gas is sitting for 12 months.

People worry a lot about fuel systems, but if you start with a clean system, there isn't a ton to worry about.


Maybe I'm a minority on this subject though. I don't do anything to my small engines either, and they fire right up every year. Every year I just roll the snow blower in after the last storm, and next winter it fires up and goes. Same with lawn mowers and other small engines. Maybe I just made the right sacrifice to the fuel gods.

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Re: How often do you replace your fuel filter?

TheEngineer wrote:

Maybe I just made the right sacrifice to the fuel gods.

Do you have ethanol free gas in your area?  My mower usually takes a little extra effort after winter, chainsaw is usually fine cause I buy the expensive premix fuel since I don't use it a lot.

I dunno about older cars but newer cars that still had fuel filters had a 30k interval and new new cars don't even have a filter (a serviceable one that is)

I know we use gas faster racing but I wouldn't bother replacing my filter unless I knew I had dirty tank problems.  Maybe after a lot of races I would for cheap insurance but definitely not every race.  We also pulled the pump and everything looked super clean.

  • Registered: 2018-02-04
  • Posts: 308

Re: How often do you replace your fuel filter?

If you put plenty of Stabil in it between races it should be fine. Small carbureted engines suffer more from varnish/sludge than do higher pressured fuel injection systems.

  • From: Flagstaff, AZ
  • Registered: 2020-09-05
  • Posts: 50

Re: How often do you replace your fuel filter?

Thanks all, good to hear that sitting for a year with Stabil shouldn’t cause new gunk to build up!

  • From: NH
  • Registered: 2010-01-20
  • Posts: 3,299

Re: How often do you replace your fuel filter?

Zacks wrote:
TheEngineer wrote:

Maybe I just made the right sacrifice to the fuel gods.

Do you have ethanol free gas in your area?  My mower usually takes a little extra effort after winter, chainsaw is usually fine cause I buy the expensive premix fuel since I don't use it a lot.

Nope. Normal ethanol modified gas goes in all my stuff. Pulled out the leaf blower today, hasn't been used in over 12 months. Started on the second pull. I put it away with half a tank with no stabilizing additives. Chainsaw fired up on the first pull after 10 months of no use. Like I said, I've done nothing but put my small engines away as they were when I turned them off for over 10 years now and they always work. I put normal gas, from different stations, and the only additive I ever use is 2-stroke mix for those engines that need it. Maybe someday my luck will change.

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  • From: Columbus, Oh
  • Registered: 2020-05-19
  • Posts: 313

Re: How often do you replace your fuel filter?

You guys still have fuel filters?

Ours is removed because, well, merkur problems. There's a filter sock on the fuel pickup that we check as yearly maintenance.

Normally the carburetor on our car will chug through old gas pretty well even after sitting. We do have a fuel filter on our transfer barrel (flowrite pump/filter system), so the gas we're putting in the car at the race itself is pretty cleaned up.

I toss in a bit of stabil and shake the car a bit as part of winterization since it freezes pretty well in Ohio.

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  • From: Camarillo, CA
  • Registered: 2021-03-26
  • Posts: 385

Re: How often do you replace your fuel filter?

Adding into the "don't worry too much"... I just remembered that our 735i sat for 3-4 years, served as a rat porta-poty for the entire period, and started right up with the 3-4 y.o. gas after a jumpstart and tapping the starter with a hammer.. didn't even add fuel to dilute the mix. Still haven't changed the filter, and it only broke 4 times over an 8 hour test day... but none of those failures were fuel system related.

I'd bet the issues you were having were from the car sitting for a while? It'll probably work itself through... running ~100 gallons of gas through it over a weekend works great as a cleaner.

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  • Registered: 2013-11-15
  • Posts: 670

Re: How often do you replace your fuel filter?

KeiCarMike wrote:

You guys still have fuel filters?

Ours is removed because, well, merkur problems. There's a filter sock on the fuel pickup that we check as yearly maintenance.

Normally the carburetor on our car will chug through old gas pretty well even after sitting. We do have a fuel filter on our transfer barrel (flowrite pump/filter system), so the gas we're putting in the car at the race itself is pretty cleaned up.

I toss in a bit of stabil and shake the car a bit as part of winterization since it freezes pretty well in Ohio.

I don't think I would want to try that on a fuel injected car.

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Re: How often do you replace your fuel filter?

rb92673 wrote:

I don't think I would want to try that on a fuel injected car.

Try what, no fuel filter?

I don't think any gas cars have come with fuel fuel filters for 10+ years now, not sure about domestic trucks but still.

14 Reply by rb92673 (edited by rb92673 2023-04-18 07:51 AM)

  • Registered: 2013-11-15
  • Posts: 670

Re: How often do you replace your fuel filter?

Zacks wrote:
rb92673 wrote:

I don't think I would want to try that on a fuel injected car.

Try what, no fuel filter?

I don't think any gas cars have come with fuel fuel filters for 10+ years now, not sure about domestic trucks but still.

Try and run without an in-line fuel filter.   As I understand it fuel filter socks are 60-80 microns while FI fuel filters are about 10 microns.  The Lemons environment isn't very clean and transferring fuel from pump to jug to car introduces a lot of chances for contamination in my experience in the west.

Perhaps newer cars have filters built in to the fuel pump assembly?  No idea.

I know my truck has two fuel filters that need to be changed every 15k miles, but its a diesel.

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  • From: Lyndeborough, NH
  • Registered: 2011-05-22
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Re: How often do you replace your fuel filter?

A great deal of newer cars have a "lifetime" fuel filter incorporated into the pump assembly or otherwise in the tank.

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Re: How often do you replace your fuel filter?

you guys have fuel filters?
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