Re: New gas leak

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Posted by Tim Daley(MI) on June 09, 2020 at 07:36:18 [URL] [DELETE] :

In Reply to: New gas leak posted by Frank (WNY) on June 08, 2020 at 16:22:19:

HiYa Frank-
I know you know most of this already but I will post for those who don't and to ensure the info gets archived for future use. You don't want any fuel leaks; that is a recipe for disaster. Don't try band-aid/quick fix things to use like pipe dope, electrical tape, or Teflon Tape. They never work anyway. Fix the problem right.

We never used to have issues with the Fuel Sediment Bulb Assemblies until they started coming from Cheena. Even India and Brazil made good ones. I've had boogered up threads on main intake, vinyl valve seat gaskets (they'll leak), and wrong threads on fuel lines. The major issue with the sediment bulb is when the seal in the valve stem wears out, and they will, and the leaking starts. It is best to never remove the Bulb Assembly from the tank; only if you need to clean the internal screen. Replace the Valve Stem Assembly when it is time. Replacing the Valve Stem Assembly, p/n APN-9194, is usually all that is needed -it is the ONLY wear part in the Bulb. Now, I highly recommend you apply a dab of Theadlocking Material on the 8-32 screw that secures the Valve Knob onto the stem with. New units tend to loosen in the field, fall off, and get lost forever. You never have to remove the knob so it won't be a hindrance and you get a new screw and knob with the new stem.

One of the other major problems also with the new Bulbs is the fuel line threads. The Threads on the Bulb for the unit AND the brass elbow carb inlet are special threads designed for fuel and brake lines. The thread size is 7-16-24 UNS. The fuel line is 1/4 steel. New Bulbs may use metric or just wrong sizes and guys too will try to do their own thread chasing with the wrong sizes. Always use your fingers to start the flare nut inserts and use your other fingers to help guide the fuel line. The line tension can bind and hinder proper insertion. Cross threading is the major cause of stripping the fuel line inlet threads and thus will leak. Always use a 7/16" Flare Nut Wrench and never use pliers, channel locks, an adjustable wrench, or vise grips. Rounding off the flare nuts will occur and you never want that. Always use the OEM cork gasket on the glass bowl -never rubber or plastic. When cleaning bowl and screen, replace with a new cork gasket. Be sure to remove any old cork on glass rim and inside Bulb Assembly. Take a sheet of medium grit sandpaper, place it on the table, lightly run glass bowl rim around to remove old cork and gum.

The main causes of fuel leaks are #1, #2, and #3 sediment bulb valve stem. The valve stem is the only working part in the system and it will wear out the seal on it and leak. It is OEM Ford part number APN-9194 and costs $6-$8 at reputable dealers like just8Ns.com. If you pay anymore than that then they are ripping you off. #6 failure is from worn, cross threaded, or wrong fuel line fittings at sediment bulb inlet and/or at brass elbow carb inlet. Use the correct OEM-type fuel line, made exact and pre bent too. Using plastic, copper, nylon, or rubber is NOT recommended. Leak #4 comes when fellas leave the fuel valve knob on when they shut down the tractor. If seal is getting bad, it will leak if left ON and/or when opened. Leak #5 can be caused by backed up vacuum in stem if gas tank vent is plugged, and leak #7 can be caused for same reason if brass fuel line inlet at carb is plugged at the filter.

#1. OEM FORD APN-9194 SEDIMENT BULB & VALVE STEM VIEW DIAGRAM:

#2. APN-9194 SEDIMENT BULB VALVE STEM FUEL:

OEM SEDIMENT BULB ASSEMBLY & VALVE STEM:
#3.

#4. OPEN VALVE STEM 2 FULL TURNS FOR MAIN OPEN POSITION, FULL FOR RESERVE POSITION, OFF POSTION WHEN NOT IN USE:

#5. GAS TANK VENT PLUGGED, MAY CAUSE NO-FLOW CONDITION:



FORD TRACTOR FUEL SEDIMENT BULB FILTERS:

-There are 3 fuel filter screens in the OEM N-Tractor system design You DO NOT need to add your own external type filter. The OEM fuel screen system works just fine. If the first screen, up inside the Bulb Assembly inside the gas tank gets plugged with dirt, it's time to pull the gas tank and clean it out, and possibly recoat it. The brass elbow screen at the carb is often neglected or forgotten. When it gets plugged, it can cause carb fuel flow issues.


FORD 9N/2N ESENTIAL OWNER/OPERATOR/PARTS/SERVICE MANUALS:

FORD 8N TRACTOR ESSENTIAL OWNER/OPERATOR/PARTS/SERVICE MANUALS:


Tim Daley(MI)


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