Tank Vent follow-up

Jeffrey Walker walkerjl at charter.net
Sun Jul 8 21:31:36 PDT 2007

Upon writing this I recalled that I really needed to change my fuel line and
filter... the line is showing its age, and the filter is 4 years old.

The filter I used is made by (cough cough) Fram, model G3515.  It has a
metal body and fits the fuel line perfectly.  Normally I wouldn't buy
anything made by Fram, but this filter works just like I want, is nice and
small and unbreakable.  It isn't a fine, high efficiency filter with a
pleated paper medium.  It has just a very fine mesh screen inside it that is
fine enough to keep out anything larger than a grain of sand, actually
probably the size of half of a grain of sand.  (I cut my old one open.)
Just a little bit of gunk in the very bottom of the filter, other than that
it looked OK.  But then again, I live in a desert environment with very
little if no rain, (Temperature today was 92F with 18% humidity.) thus I
have ZERO rust in my tank.  My bike is always covered when its parked in a
CycleShell, and with an additional cover on it in the CycleShell in the
wintertime. (BTW, If you don't have room in your garage for your bike, or
don't have a garage, CycleShells are the cat's ass!)

I'm also very picky about only getting my gasoline from a very busy,
reputable station that has high turnover in its tanks, and always has.  I
used to be so anal about my fuel sources that I would do a water separation
test on the fuel from various stations.  I'm also very careful to lay the
bike up with the tank completely full of Stabil treated gas, then I pull the
vacuum line to the petcock and run the bike until it dies to get most of the
gas out of the carbs.  (Sometimes I drain them too, but not always.)  In the
spring I drain the gas out of the tank and put it in my car's tank, then
refill with fresh gas.  I'll even do this if I'm going to be traveling or
otherwise unable to ride for a month.  Stabil is very cheap insurance.

Bottom line, I've never had a problem with gasoline ever since I've gotten
really picky about it, shortly after I realized that I had a 40 gallon tank
of untreated fuel go bad in my boat after it was laid up for 3 months.  (Did
you know that there is a variety of algae that grows in gasoline and

Anyway, best of luck with it,

Jeff in Washington

-----Original Message-----
From: Larry Zoia [mailto:phezanthawk at wowway.com] 
Sent: Sunday, July 08, 2007 4:34 PM
To: Jeffrey Walker; gpzlist at micapeak.com
Subject: Re: Tank Vent follow-up

> I'm not convinced that boring out the inlet and outlet of the filter you 
> are
> using will significantly reduce the pressure drop you are experiencing
> across the filter.  I believe that it is the filter media itself that is 
> the
> culprit.

Either way, the filter is bad ju-ju no matter what the
exact mechanism of obstruction of flow.

> Anyway, I bet if you switched the filter to a different model or even just

> a
> new one you'll have better flow.

This one is new, but yes, I agree as I have had other
GPZ's in the past and had not encountered this problem.

>>  Your vodka bottle test is innovative, what I
> call the bucket and stopwatch method for determining flow rate.

I find many uses for empty plastic pint bottles of vodka.
I use them to measure oil for two-stroke fuel mixing,  They can be used as 
armor and banded together to
make floatation devices.  I have even used them
to protect items in boxes I'm shipping.  The plastic bottle is indeed a 
boon....AND it comes filled with vodka.  What a country!

(And I'm a
> pro, I test leak rates of primary containment isolation valves at nuclear
> power plants, in accordance with 10 CFR 50 Appendix J. see

Something like Homer Simpson's job?

> So you have identified one probable cause:  the filter may not flow 
> enough.

I'm convinced this is the cause.  I've spliced the fuel line back together 
and will test it out.  This bike was run
about 40k without a filter, and I installed the filter upon
buying the bike and cleaning and rebuilding the carbs.

The vacuum hose is patent, I'm sure.  I will, however my test ride works 
out, pull the petcock and at least inspect and probably rebuild it.

Uh-oh.  I just remembered that I did the vodka bottle
test with the gas cap open so that I could test one thing at a time.

I guess a non-measured gross test could be done with
the gas cap closed to see if the whole tank readily drains.....but I think 
the cap is okay....unless it's not.

larry in Michigan

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