FUEL FILTER?

FJFAST · May 06, 2016, 05:06:15 PM

I was reading an old post and there was a statement about NOT running an in-line fuel filter on an '84-'85 but they didn't say why. What would be the reason? I've always run one. Any suggestions on a good one?

Greg

Pat Conlon · May 06, 2016, 05:36:05 PM

You can run a screen filter ok, if you want, I don't know why you would need it because your petcock already has (or should have) a screen on the inlet.

A traditional pleated paper filter imedes (blocks) the flow of fuel. Just a fact. They are designed for fuel pump applications. If you put one on a gravity flow FJ, you won't notice it when your tank is full and the head pressure pushes the fuel past the paper filter. You will notice it when your tank is 1/4 full or less, and the head pressure is lower and/or when the the paper filter gets dirty and blocks the fuel flow ever further.

Traditional fuel filters come on the fuel pump FJ's, no problem there with the pump pulling the fuel thru the filter (the filter is upstream of the pump)

Proceed at your own risk.

mr blackstock · May 07, 2016, 04:35:13 PM

Hello Pat,

I have read this warning about using paper fuel filters in a few posts. I have been using such filters on my bikes for years, usually because one of my early bikes had a screen filter as part of the petcock inside the tank, and on the one occasion I removed the petcock, (on some old bikes, if it ain't broke, don't fix it) the filter was fine. However, at some point it failed as my carbs became pretty blocked, and as I did not know when the screen failed I was not sure for how long my 70's tank had been contributing to the crud build up in my carbs. After that I always used such filters, and whenever I had reason to remove the tank, the filter was always full of fuel. I often run the tank down to quite low levels also.

Perhaps the flow rate of the filter might restrict fuel flow at wide open throttle, I do not often get near that mark. Also I have never owned a bike with a fuel pump. And a good thing about the paper filter is that in the event it gets dirty, it is easy to tell and cheap to replace. Considering how finicky the FJ carb is, I consider the paper filter a good investment.

cheers, Gareth

oldktmdude · May 07, 2016, 07:16:58 PM

Gareth, I'm with Pat on this one. I tried an inline filter when I first bought my FJ. It does not flow enough fuel (gravity feed) to keep the engine running to my satisfaction. A different riding style might work but that's not fun for me!

Regards, Pete.

FJFAST · May 07, 2016, 07:27:41 PM

I replaced the pet clock last year so the screen is brand new. I've run the inline for years but I see both sides of the issue. I also tend to run tank low on gas- a bad habit I know.

mr blackstock · May 07, 2016, 07:32:09 PM

Over the next few days I might try an experiment. I will rig up my remote fuel tank, film the filter and run the bike through different rev range to se how the level acts.. I might notice the fuel dries up, or remains full. And a small correction, I used to use the paper filter, recently I went with a metal sponge type inline filter.

But I am curious, and I reckon my experiment should be interesting. I use the same tank when I am balancing the carbs, but I do not rev it beyond 2k.

cheers, Gareth

oldktmdude · May 07, 2016, 07:46:35 PM

Quote from: mr blackstock on May 07, 2016, 07:32:09 PM
Over the next few days I might try an experiment. I will rig up my remote fuel tank, film the filter and run the bike through different rev range to se how the level acts.. I might notice the fuel dries up, or remains full. And a small correction, I used to use the paper filter, recently I went with a metal sponge type inline filter.

But I am curious, and I reckon my experiment should be interesting. I use the same tank when I am balancing the carbs, but I do not rev it beyond 2k.

cheers, Gareth

Gareth, I think you'll find running it in the shed with a aux tank and running it hard, out in the real world are two different things. You need to apply a load to the engine, either by riding on the road or on a dyno. The inline filter that I used would never fill completely, it always had an air gap in it. It hung below the level of the carbies so should have filled completely.
Do your experiment and if you can find a way to use an inline filter sucessfully, I'll gladly follow your lead.
Regards, Pete.

FJmonkey · May 07, 2016, 08:14:13 PM

I say try it, have a spare barb fitting if you need to pull the filter out on the side of the road. Nothing bad is gonna happen but having to pull over and bypass the filter.

jscgdunn · May 09, 2016, 08:37:53 AM

On the 86 (now sold) we had have an inline fuel filter. Bike ran fine but we did notice it could not keep up to an 1100 and my 1200 over a wide open run up to about 110 mph. Even wide open it not seem to be staving for fuel....ie no missing...just could not keep up. May have been motor was a bit weak. Certainly for normal riding no issues at all.

Jeff

mr blackstock · May 09, 2016, 11:04:58 PM

Well I completed the experiment. The bike had half a tank of petrol, I left the tank on the bike, just put some chocks under it so I could see and film the filter. I ran the bike for around 2 minutes at various rev ranges and the fuel level in the filter remained constant regardless of revs or for how long the engine was revving.

The link below will take you to the video. I have spoken to another bike rider at work who used to race old 80's bike semi profesionally, and he stated he always used filters. He suggested that flow rate might be affected if you were sucking in more than a litre a minute, but he is of the opinion that most standard road bikes would not pull more than that amount.

https://youtu.be/0VvnXuv16Yk

Based on my research I think it is safe to use a fuel filter. Bearing in mind other factors can affect fuelling, route of the fuel line, crimping, too much fuel line, etc.

cheers, Gareth

oldktmdude · May 09, 2016, 11:13:27 PM

Gareth, did you not read my earlier post. Engines use substanyially more fuel when under load. Take the bike for a hard, high revving ride. Let us know your results then.
Regards, Pete.

Pat Conlon · May 09, 2016, 11:29:38 PM

Awwww geese Pete, don't say that...next thing we will see is Gareth doing a 100mph uphill run, with the blocks under the tank and while holding the camera with one hand....
(or a trip to an eddy current dyno is in order)

Serously, thanks for the info. Gareth. This opinion I've posted was formed by me after several other FJ members, over the years, have reported issues.

Put 1/2 gallon in the tank, and put in a dirty fuel filter, ride up hill....160kph, in a head wind, and get it on video....

Klavdy could do it, you can too.

I like fuel filters....I'm still going to convert my '84 over to a fuel pump...

oldktmdude · May 09, 2016, 11:39:24 PM

Quote from: Pat Conlon on May 09, 2016, 11:29:38 PM
Awwww geese Pete, don't say that...next thing we will see is Gareth doing a 100mph uphill run, with the blocks under the tank and while holding the camera with one hand....
(or a trip to an eddy current dyno is in order)

Serously, thanks for the info. Gareth. This opinion I've posted was formed by me after several other FJ members, over the years, have reported issues.

Put 1/2 gallon in the tank, and put in a dirty fuel filter, ride up hill....160kph, in a head wind, and get it on video....

Klavdy could do it, you can too.

I like fuel filters....I'm going to convert my '84 over to a fuel pump...

Pat, I happen to be one of those that been through the trial and error method with inline filters. I fitted one and like Gareth tried it out on a stationary bike, going through various revs, with no problems at all. Took it for a test ride and within half an hour experienced fuel starvation problems. The further I went, the worse the symptoms became. Ended up removing the filter and no more problems. I would prefer to use an inline filter but will not at the expense of engine performance.
Regards, Pete.

Pat Conlon · May 10, 2016, 01:31:28 AM

Pete, yep, other folks have said the same thing... going way back to the days of the Netpath and Yahoo lists.
(I can't believe I've been hanging around FJ folks for so long)

Fuel filters are good.
With the eathnol laced fuel we get here in the states, fuel filters are needed.
Our steel tanks are not getting any younger.

If you think about it, those engineers at Yamaha are kinda smart. If they thought they could just add an inline paper filter to the gravity flow bikes they would have. I think the engineers (and most people) agree that having a fuel filter is a good idea, so starting with the '89+ FJ's they added a fuel pump, just so they could run a fuel filter.
That's the explanation that has made the most sense***
There is no other reason they would add cost and complexity to a product without benefit. A fuel pump, by itself, is not a benefit. Gravity flow has proven to work fine, so why add a fuel pump? ($$)
So they could run a fuel filter.

***Alternate theory: maybe they wanted to get away from the vacuum petcocks?

Cheers lads

FJ1100mjk · May 10, 2016, 07:17:28 AM

Don't know why some folks continue to dick around with an accessory inline fuel filter, on the gravity-fed models. Just clean the tank (plenty of methods out there), and be done with it.

Even Yamaha, offers their own cleaner...

Yamaha Fuel Tank Cleaner

I used a similar product sold by Sudco years ago, and haven't had a problem with jet-clogging particles, or partially-blocked float needles since.

News:

FUEL FILTER?