second fuel filter

[squidley63]

After cleaning and recleaning carbs on my fj I'm contemplating adding a second fuel filter after the pump to try and get even more of the small junk out of the gas before the carbs. I have a 50 micron filter on the suction side and am thinking of adding a 5 micron filter after the pump. I wonder if anyone else has added a second filter and if it made a difference on how long you can go between cleanings.

[Pat Conlon]

I don't know the answer...if a second filter would or would not, be enough to impede the flow from the pump to the carbs.
There is a test you could try....I recall somewhere there is a volume test you can perform to see if the fuel system delivers the correct amount of fuel, based on volume delivered over a set amount of time.
You use a pail to measure the output volume. Sorry, I don't know the specifics...find out and try this measurement test with both filters installed...knowing and understanding that this flow, whatever flow you have, will diminish when the filters load up.

Re: Carb Cleaning, almost all of the required cleaning is due to the eathnol in the fuel reacting with the carb internals...no amount of filtering will prevent that.

[squidley63]

I do know any filter below 50 micron on the inlet side of pump does cause enough restriction within a month or so to cause issues as I had one installed previously and had some fuel starvation issues on the highway. I run a second filter on my truck to help the carb go longer between cleanings and it does seem to help a little anyway.

[Jonfife]

After cleaning and recleaning carbs on my fj I'm contemplating adding a second fuel filter after the pump to try and get even more of the small junk out of the gas before the carbs. I have a 50 micron filter on the suction side and am thinking of adding a 5 micron filter after the pump. I wonder if anyone else has added a second filter and if it made a difference on how long you can go between cleanings.

dirty fuel or rusted tank? Simple test. Run your finger around the inside lip of the fuel tank...when you pull your finger out and it's brown, rust. No fuel filter can prevent fine microns of rust getting past filter. Lot's of folks mistake brown sledge in carb float bowls to be from dirty fuel, when in fact it fine pacticals of rust. Time to derust and line tank

[squidley63]

I derusted and lined the tank last year. I don't seem to have much in the way of junk in the fuel tank but when I poured the fuel through a coffee filter it did leave a little discolored area with a fine dust feel to it. I am just trying to collect at least a bit of this stuff before they enter my carbs.

On my truck I've noticed a lot happier carb after putting a 4 micron filter on it. After the first couple of months I changed out the filter and noticed a lot of debris in the filter when I took it apart. I just think its a good thing to try and prefilter the fuel as much as possible before the carbs to keep them happy.

I was hoping someone else had tried it before so I could get a minimum filter size that they had used. I don't think I need to go all the way to a 1 micron filter but maybe I should. I guess I will start with a 4 and go from there to see what works best.

[FJ_Hooligan]

Rather than continuing to try to filter it out, you need to identify the source of the debris and fix that.

Sounds like rust.  I don't think you can get a filter small enough to filter out all rust particles.  Find/fix the source.

[red]

Squidley,

Okay, I probably know all the jokes, but if rust in the fuel is the problem, you could keep it out of the carbs with a magnet.  
NO, I don't think it will increase the octane, or fuel mileage   but rust will be captured by a magnet.  A powerful super-magnet (neodymium) taped to the fuel filter will do about what a similar magnet would do, attached to the oil filter, which is to attract and hold even microscopic iron (rust).  Do not remove the magnet until the filter is removed from the bike, of course.

Donning flame suit, ducking and running,
Red

[Jonfife]

I derusted and lined the tank last year. I don't seem to have much in the way of junk in the fuel tank but when I poured the fuel through a coffee filter it did leave a little discolored area with a fine dust feel to it. I am just trying to collect at least a bit of this stuff before they enter my carbs.

On my truck I've noticed a lot happier carb after putting a 4 micron filter on it. After the first couple of months I changed out the filter and noticed a lot of debris in the filter when I took it apart. I just think its a good thing to try and prefilter the fuel as much as possible before the carbs to keep them happy.

I was hoping someone else had tried it before so I could get a minimum filter size that they had used. I don't think I need to go all the way to a 1 micron filter but maybe I should. I guess I will start with a 4 and go from there to see what works best.

Been there done that. My guess...the tank lining may not be up to par. I had local company derust and reline my tank, only to have the rust return after a year. New card rebuild ruined. Send all my tanks off to George at fuel tank services. Motorcycle Fuel Tank Services
www.fueltankservices.com/
The World Leader in 100% Rust Removal and Permanent Motorcycle Fuel Tank Liners.