[AT] OT - JD STX38 fuel problems

Mon May 24 00:45:31 PDT 2004

Mike:

Let's think about this a minute. How big is the inside of the filter that
you can see through the window? The fuel usage on a STX38 isn't all that
high even while mowing. I'm just not sure the window is a good indicator of
anything being incorrect. The required flow isn't that high. How long does
it take to empty the tank while mowing? A long time. There may be enough gas
flowing in the filter that you can't see it all through the window. 

Why it isn't full all the time is a question worth pursuing but all I can
think of is there must be some back pressure but I don't know where it is
coming from. Is it possible the filter is quite high in comparison to the
level of the fuel in the tank? I think we need to know what the innards of
the filter are in order to really decide that it not being full all the time
is really a problem.

As far as it now running w/o ever cutting out can be due to many things.
Maybe there was a partial blockage somewhere in the system that is now
cleaned out. Maybe it has something to do with going up or down hills or
being on a side hill. Or what the level of the fuel is in the tank when you
do that. I think what I would do is run the sucker until the problem
returns. Right now I think we are chasing ghosts. 

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 Mike S Meulenberg
Sent: Sunday, May 23, 2004 4:51 PM
To: at at lists.antique-tractor.com
Subject: Re: [AT] OT - JD STX38 fuel problems

Saturday, I pulled the carb and went through the whole thing to make sure
nothing was plugged. Before I pulled it off, I removed the bottom bowl to
reveal the float. I manually moved the float up and down and had good
flow inside the bowl. I noted that there were no scrape marks, and the
float isn't adjustable. I put everything back together, and then mowed
the lawn. It ran the entire time with the filter empty, but never quit. I
wasn't able to get a JD filter because the dealer was closed. I think
I'll slap one of those on and then take Larry's advise:
"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."

Thanks for all the help, it's appreciated.

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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