[AT] OT - JD STX38 fuel problems

Thu May 20 18:01:47 PDT 2004

Most of the aftermarket fuel filters you can buy are designed to be used
with a fuel pump.  The pump presure pushes (or pulls) the fuel through the
filter.  Since most of our tractors are gravity flow fuel systems filters
restrict the flow too much.  If you need to use an inline filter make sure
it is one sized for a much larger engine than the tractor you intend to use
it on.  That way it should gravity flow enough to keep you running.   For
example, if you have a 4 cyl, 35 hp tractor try a filter that would work on
a 460 Ford or a 454 Chevy.

Charlie
----- Original Message ----- 
From: "Mike S Meulenberg" <msm10301 at juno.com>
To: <at at lists.antique-tractor.com>
Sent: Thursday, May 20, 2004 6:08 PM
Subject: Re: [AT] OT - JD STX38 fuel problems

> I can try an OEM filter, but I bet it comes off the same line as my NAPA
> filter. I'm curious if the original filter was more of a screen versus a
> paper element. Phil, I tried vertical and horizontal, no change. I'll
> keep monkeying with it. Thanks everyone for all the help
> Regards,
> Mike
>
> On Thu, 20 May 2004 09:48:08 -0500 "Larry D. Goss"
> <rlgoss at evansville.net> writes:
> > What you've described here sounds like a typical vapor pressure
> > problem,
> > Mike.  Greg's suggestion about a different brand of fuel filter may
> > solve it.  Changing blends or octane ratings of gasoline may have
> > the
> > same effect.  I've never been able to predictably determine when
> > the
> > fuel supply system is going to react the way you are describing it.
> > When I replace the fuel filter on John Deere equipment, I always use
> > the
> > OEM parts, but sometimes the filter fills and other times it
> > doesn't.
> > The running condition can change simply because of changes in the
> > weather.  When I'm working on a customer's machine, I simply run
> > the
> > engine with hood closed and with all the side panels in place until
> > everything is up to ordinary operating temperature.  If the engine
> > doesn't falter, I ship it back to the owner regardless of whether
> > the
> > fuel filter fills while it's running.
> >
> > Remember the good old days of vapor lock?
> >
> > Larry
> >
> > -----Original Message-----
> > From: at-bounces at lists.antique-tractor.com
> > [mailto:at-bounces at lists.antique-tractor.com] On Behalf Of Mike S
> > Meulenberg
> > Sent: Wednesday, May 19, 2004 10:42 PM
> > To: at at lists.antique-tractor.com
> > Subject: Re: [AT] OT - JD STX38 fuel problems
> >
> > I mowed again tonight, and here's what I observed:
> > 1. When I last left the mower the filter was empty and the shutoff
> > was
> > open, when I looked tonight
> >      the filter was full.
> > 2. After mowing for a while the filter was empty, but it didn't
> > quit.
> > 3. About 3 hours after mowing the filter was again full.
> >
> >
> > I'm beginning  to wonder if the fuel filter is providing too much
> > resistance to flow for a little mower without a fuel pump. Maybe
> > the
> > paper cartridge is too restrictive. I will check the carb again to
> > look
> > for any signs of the float sticking.
> >
> > Thanks,
> > Mike
> >
> >
> > On Tue, 18 May 2004 21:28:14 -0700 "Dean VP" <deanvp at att.net>
> > writes:
> > > Mike:
> > >
> > > Another thought. Is it possible that the float is hanging up in
> > the
> > > bowl
> > > because it has been bent accidentally to one side? Or the needle
> > > getting
> > > stuck in the seat occasionally? Or the float isn't set quite right
> >
> > > to allow
> > > enough needle travel? Maybe due to heat?
> > >
> > > Can you get to the hose that runs from the in-line filter to the
> > > carburetor?
> > > If you take this connection loose at the carburetor is the flow
> > > always good?
> > >
> > >
> > > This is the demarcation line. If the flow isn't good at the end of
> >
> > > the hose
> > > that connects to the carburetor then the problem is further back
> > > towards the
> > > in-line filter and/or tank or lines. If the flow is good, then the
> >
> > > problem
> > > is in the carburetor. The parts list doesn't show how the hose
> > > connects to
> > > the carburetor, but maybe there is some crud at the inlet point,
> > > maybe a
> > > partially plugged screen or sticking float or needle valve. All it
> >
> > > would
> > > take is a small piece of crud at the needle and seat to cause the
> >
> > > symptoms
> > > you are experiencing.
> > >
> > > I keep thinking of a vapor lock but I've not seen that when one
> > has
> > > rubber
> > > hoses feeding the gas.
> > >
> > > Since you don't have the solenoid that shuts off the gas and you
> > are
> > > not
> > > losing fuel into the carburetor when the tractor is parked, then
> > the
> > > needle
> > > must always be shutting off the fuel flow properly. That kind of
> > > precludes
> > > the possibility of some crud at the needle to seat interface and
> > it
> > > would
> > > flood occasionally too. Unless you are always shutting off the
> > fuel
> > > valve
> > > after each usage.
> > >
> > > To me checking the hose inlet to the carburetor will lead you to
> > the
> > > problem.
> > >
> > > Dean A. Van Peursem
> > > Snohomish, WA 98290
> > >
> > > What people can dream, people can do! George W. Bush
> > >
> > > www.deerelegacy.com
> > >
> > > http://members.cox.net/classicweb/email.htm
> > >
> > >
> > >
> > >
> > > -----Original Message-----
> > > From: at-bounces at lists.antique-tractor.com
> > > [mailto:at-bounces at lists.antique-tractor.com] On Behalf Of Dean
> > VP
> > > Sent: Tuesday, May 18, 2004 9:58 AM
> > > To: 'Antique tractor email discussion group'
> > > Subject: RE: [AT] OT - JD STX38 fuel problems
> > >
> > > Vaughn:
> > >
> > > Seems to me it has everything to do with fuel flow if it is not
> > > working
> > > properly. If the wiring is intermittent or the coil in the
> > solenoid
> > > has some
> > > windings that short out it may not be opening properly or staying
> >
> > > open
> > > properly during run time. It appears to be opened by turning on
> > the
> > > switch
> > > and is supposed to stay open until the switch is turned off. If it
> >
> > > isn't
> > > opening properly or is intermittent it would explain the symptoms
> >
> > > present.
> > > It may start acting up only after running for awhile as it heats
> > up.
> > >
> > >
> > > Dean A. Van Peursem
> > > Snohomish, WA 98290
> > >
> > > What people can dream, people can do! George W. Bush
> > >
> > > www.deerelegacy.com
> > >
> > > http://members.cox.net/classicweb/email.htm
> > >
> > >
> > >
> > >
> > > -----Original Message-----
> > > From: at-bounces at lists.antique-tractor.com
> > > [mailto:at-bounces at lists.antique-tractor.com] On Behalf Of Vaughn
> >
> > > Miller
> > > Sent: Tuesday, May 18, 2004 4:50 AM
> > > To: at at lists.antique-tractor.com
> > > Subject: RE: [AT] OT - JD STX38 fuel problems
> > >
> > > The solenoid at the Carburetor bowl shuts off fuel to the main jet
> >
> > > to
> > > prevent backfire, and will have nothing to do with the flow into
> > the
> > > carburetor.
> > >
> > > Vaughn
> > >
> > > >>> deanvp at att.net 5/18/04 1:21:01 AM >>>
> > > <snip>
> > > 4.) What does the solenoid do in the carburetor bowl? Does this
> > just
> > > let
> > > fuel flow when the switch is on? Doesn't look like a pump. Is
> > this
> > > solenoid
> > > acting up? Wiring loose or corroded? This may be where the problem
> >
> > > is. Is
> > > the carburetor bowl clean inside?
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