Jeezus

iTrader: (4)

What is the best fuel filter out there? I think I heard of K&N having something that filters to 40 microns or something. Reason being, my car hates me. Lately, I have been getting trash in the carburetor. I have had 3 different completely rebuilt Nikki carbs put on. First one ran great, then started loading up real bad, and barely made it back. This was after about a mile of driving. Put on carburetor #2, ran great for about 3 weeks, then secondaries would load up and I could not use them. Changed the fuel filter, no gunk in it at all. Cleared out the jets, e tubes, float bowls and fuel lines. Ran great, then about 3 miles later back to how it was. Put on carb #3 and no matter what it would just load up.

Now I have carb #2 on there. I have a fuel filter, then fuel pump, then regulator, then a clear filter, then the carb. The clear filter has cartridges you can replace. Both filters are brand new, and they both show nothing in them. Turn on the car, go for a drive, it is great. Come back and secondaries are gone again. I take the carb top off and look into the float bowls. Tiny flecks of crap at the bottom. Look at both fuel filters again, NOTHING IN THEM. All new fuel lines and still getting gunk in the carb. Where is it all coming from?! I have not had my tank cleaned, which I am 70% sure is where the problem is, but how can the gunk get through 2 filters and end up in the carb?

Now I have my OER back on. I dont really care if I get 14mpg instead of 22 now. The 7 had no ***** before, and now I can spin second and chirp third on a horrible tune.

Any ideas where the gunk can be coming from and better fuel filters to use?

Vashner

Go to dealer and get mazda part. Otherwise they should be very similar. Also don't run it empty. Keep 1/4 tank or more helps to keep rust and crud out.

As far as where it's coming from it could be corrosion inside the tank or the pipe.

kgray

WIX! nothing other than them either!

badandyrx7

i dont think this is caused by the fuel filters. you should run some gas in to a coutainer out of the carb line to see if you get any "flakes" from the tank.

Jeezus

iTrader: (4)

I get flakes. What I want to know is why it can ,make it through 2 fuel filters like nothing.

robs_seven

iTrader: (1)

stu you ever changed all your rubber lines out? when i had problems with mine getting crap in it i finally gave up on the filters catching everything and ended up draining the tank cleaning it the best i could, then also had 3/8 aluminum fuel line ran and also replaced all the rubber lines. I found that the old lines were flacking apart as well as the old metal lines had rust in them. Hey also if you pull your tank i thank there is some stuff you can put in the to coat the tanks inside. i know that the guy that live down from me did it, pm him if you are interested DavidMyers53

K-Tune

iTrader: (26)

get that fuel tank properly cleaned, otherwise even when you do find a proper filter you'll be changing it out as regularly as you change carbs.

Mark_1

I agree, fix the source of the metal flakes - most likely the tank. Without removing the source of the problem will not matter what filter you use.

Jeezus

iTrader: (4)

Yeah, I am going to be dropping the tank and cleaning it, also prepping it for a turbo. I guess I will get some copper tubing as well for the hard lines.

Oh and rob, Everything fuel related has been swapped or new. Fuel filters, Hoses, carbs, no check/cut valve, fuel pump, regulator, gauge, the works.

I really dread dropping the tank

Vashner

It's not that hard compared to some other cars.

budrud

I gotta say this is the damndest thing I ever heard of. I could see the filters clogging if the tank is dirty, but I don't see how it could possibly get to the carb past 2 filters. Make sure you bump the thread when you figure it out

Vashner

Maybe your air intake is letting some dirty air in...

You might be looking at the wrong thing for the problem. Good catch on the fuel filter. Cause like I said the stock filter is good enough.

challer2000

+1 or the carquest brand (made by same company)

redbstd

ah screw all that go to a Caterpiller filter. 2 microns thats goot n clean

mikewoodkozar

Yeah, WTF, how is crap still getting through?

redbstd

when you figure at rated rpm a 15L CAT fuel pump will be pushing 80psi its not hard. But thats the secondary filter the primary is 20(IIRC) micron. Its all because inside diesel injectors there are no seals they rely upon the thickness of the diesel molecules to seal the injectors because the pressure inside those injectors can get to 33,000psi and any seal would explode. so 1 good size peice of sand can destroy an injector. wich can cost $600 new

Dan_s_young

iTrader: (1)

Copper lines aren't made to be fuel lines. Only use rubber lines or even better yet steel lines that are flared at the ends/connections.

Keeble

iTrader: (3)

what he said^^^ works the best and will give you the least amount of problems.

badandyrx7

i still dont think your getting that crap into the carb through the tank (filters) especially after your swapped everything out. i think you said you had two filters? that pertty much impossible to get anything that you would be able to see with your eyes without clogging them.

dbragg

iTrader: (7)

dropping the tank isnt hard at all. esspecially if you dont have a lot of fuel in it.

mikewoodkozar

Yeah, run that thing almost empty! I know water is 7lbs a gallon, gas cant be much different

Kentetsu

Stock fuel filter suck. Even when brand new, they barely flow enough to keep the motor fed. There are options, such as big high flowing filters the size of oil filters, but I chose to use two stock filters in parallel (not in series). That way, even if they both get clogged to the point of only flowing 50% I've still got full flow to the motor. And, replacement is still easy and only 3 bucks each.

But yeah, solve the issue first. Clean the tank and replace any lines that are suspect so you can stop chasing your tail.

FBsliderseven

iTrader: (2)

put a filter before the carb?
might be coming from the lines..not to sure about that, but cleaning the tank is a good idea.

dbragg

iTrader: (7)

i bought a filter set up from a parts store that looked like a oil filter. if you find the old thread about fuel filters i posted pics of the set up. i liked it, but it went with the car when i traded it. i also had a small filter before the carb.

did the research for you

https://www.rx7club.com/1st-generation-specific-1979-1985-18/dual-fuel-filter-mod-528445/page3/

post #67 and #74

Vashner

Did you put in any gas additive like a cleaner? That could be flushing gum and gunk out.