First gen fuel filters

C

crushed

New member
I've been having carb issues recently and wanted to hear what others were doing.

My first problem were my needles sticking open and flooding the motor. I attributed this to dirt getting wedged in there and put those tiny stock filters on top of the seats. I also bought an earls 35 micron filter. My fuel system now looks something like this:

cell -> screen at the pickup -> pump -> 35 micron filter -> brand new regulator -> carb (with tiny filters on top of the seats)

At the last race the tiny filters on the seats clogged about 12 laps in and I couldn't get any fuel to the motor. I'm not sure where this dirt is coming from, as I figured 35 micron would be smaller then those filters. Granted it took 3 races worth of lapping before the filters clogged, but I would rather not have to clean these out after every session.

What setup are you guys running and are have you seen these types of problems before?
 
Man, is this a familiar tune, LOL.

Welcome to my world. I'll save the details...

My issue is a rusty tank. I swapped to a less rusty tank, and it got better...but it's really in need of a new tank. ($and $700 to send to Mazda), or a cel, which would likely weigh more)

The work around is:

Screen over pickup --> NAPA clear inline filter --> pump/regulator (Holley) --> NAPA clear filter (on firewall) --> final adjustable regulator (on firewall) --> NAPA clear filter --carb.

In the carb, I have Grose jets. The one thing I will say for them is that the ball isn't soft, so it can't have little particles get embedded in it. On the downside, they sometimes stick open, esp after twong for some reason. That seems to have gone away.

I used other filters, but I like the disposal nature of the NAPAs, and being able to see the condition at a glance is great at the track, and they are very cheap.

At first I changed the first filter in line (after a very arduous tank cleaning session that involved a case of carb cleaner) before every session, but that's not needed anymore.

Maybe such a setup, with the final filter being the finest would work for you. The rust gunk was very fine...l
 
Biggest diameter (~2") cheap generic metal Fram fuel filter just before the regulator. I change it regularly (every 6 race weekends.)
I use the metal filters because I am terrified of rupturing a clear plastic filter. I only run 1 filter, so there is no question about wich one to change!

Tak
#29 ITA Rx-7
SFR SCCA
 
Can you actually see dirt? Is it dirt or rust? Don't ask me how to tell the difference as I do not know if rust will stick to a magnet. In either case it has to be coming from somewhere after the 35 micron filter. A rusty tank will typically clog the filter before it gets to the carb. If you're running a cell, rust is not coming from there. What type of lines are you running?

Don't ask about my car, let's just say it's slooowly coming along.
 
Hot damn, this might be a technical question I can actually answer!

My first car had a cell and I was constantly clogging the filter. I added a little inline one w/ glass tube and had to clean it after every session. Little black/dark gray specks. The source? The foam liner in the cell was deteriorating. You may need to replace it.
 
Thanks for all the replies!

I can see the dirt on the seat filters, little black specs. It does look like little bits of fuel cell foam, but who knows, it could be bits of fuel line too. I would think the 35 micron filter would take care of all that. All the fuel hoses are aeroquip and the regulator is a holley (fairly new).

I guess I'm wondering how fine the seat filters are? If they are smaller then 35 micron I can assume my fuel cell foam is deteriorating and replace it, if they are larger I would guess it's coming it's coming from the lines between the filter and carb. Does anyone know their size?

35 micron is 1.4 thou, pretty damn small but not too small that you cant see it...
 
Russ, try taking a siphon hose (or what ever) & draw some fuel from your cell & see if there is these fine black specs. Take some fuel from the top & then take some fuel from the bottom. Try to eliminate hose specs or fuel cell specs.
 
Thanks for all the replies!

I can see the dirt on the seat filters, little black specs. It does look like little bits of fuel cell foam, but who knows, it could be bits of fuel line too. I would think the 35 micron filter would take care of all that. All the fuel hoses are aeroquip and the regulator is a holley (fairly new).

I guess I'm wondering how fine the seat filters are? If they are smaller then 35 micron I can assume my fuel cell foam is deteriorating and replace it, if they are larger I would guess it's coming it's coming from the lines between the filter and carb. Does anyone know their size?

35 micron is 1.4 thou, pretty damn small but not too small that you cant see it...
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The best way to test fuel cell foam is to take the cover plate off and grab the foam between two fingers and see if it crumbles. If you suspect the foam, replace it. It is a problem that won't get better. You can get foam from the cell manufacturer or from companies like JAZ and RCI. I bought foam in bulk from Motorsports of KC for a couple of cells that I refurbished. It wasn't that expensive.

Motorsports Of KC
913-334-0477
http://www.marketworks.com/StoreFrontProfi...aspx?sfid=79094

On my car I have two carter street pumps - one for each pickup in the cell. The installation is:

Duck foot pickup > Fuel Pump > G19 Fram filter (one per pump) > -6 bulkhead tee > single -6 line to the firewall mounted Holley regulator. No other filters.

My ATL fuel cell is 2 years old. I plan on doing a foam replacement in another couple of years to be safe.

Grose Jets are cool!
 
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