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Good morning all,

To continue the new project, my friends 1994 F150, new issue. When he fills the gas tank, it has a lot of back pressure. It seems that the tank is not venting when you try to fill. So you have to go a little bit then stop, go some more then stop otherwise the thing just kicks back..:banghead One other symptom is that the fuel gauge appears to not work accurately either. When is read empty it will only take $20 worth, with is about 6.7 gallons....:banghead

Any suggestions on what to check? :whiteflag
There is only one fuel tank on this F150...

Thanks
:rockon
 

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yo;
Is it hissing when he removes the cap after driving?

check Fill & Vent Tube
Such as;

Vent Tube Replacement w/plastic flex pipe in a 95; "...i have a rubber hose inside my filler pipe and it had been cut off about an inch from where it comes out of the metal filler neck. i couldnt find any fuel hose that size that was for fuel so i got a piece of the plastic flex pipe like for a washing machine and attatched it and put it in. i tried refueling and i could run the nozzle wide open it didnt shut off until it hit 26 gal. which was full. so as long as the plastic holds up i think its fixed..."
Source: by fordsohc46 at Ford Bronco Zone Forums

Fill Pipe Depiction & Parts Break-Out Diagram
Source: by Steve83 (Steve, That dirty old truck)
http://www.supermotors.net/registry/media/283481

Vent & Fill Tube pics in pre 87 & 87 & up; "...Early trucks use a small corrugated plastic vent tube tucked into the top of the steel filler neck , but it often kinks & blocks fuel from entering the tank easily. Later trucks use a heavy plastic filler hose inside the steel vent neck, which allows MUCH easier filling.The necks are interchangeable, so it's a good upgrade for an old truck, especially if filling is becoming a problem. It also allows the use of a more modern gas cap..."
Source: by Steve83 (Steve, That dirty old truck) at Vent & Fill Tube pics in pre 87 & 87 & up; "...Early trucks use a small corrugated plastic vent tube tucked into the top of the steel filler neck , but it often kinks & blocks fuel from entering the tank easily. Later trucks use a heavy plastic filler hose inside the steel vent neck, which allows MUCH easier filling.The necks are interchangeable, so it's a good upgrade for an old truck, especially if filling is becoming a problem. It also allows the use of a more modern gas cap..."


Source: by Steve83 (Steve, That dirty old truck) at SuperMotors.net
V REST Vapor Valve (also described by F__D as the evaporative emission valve) pic
the valve on top of the tank is the evaporative emission valve (see F..D depiction 9B593) ,mounted on the top of the fuel tank )is used to control the flow of fuel vapor entering the fuel tank vapor delivery line which conducts vapor forward to the evaporative emissions canister (EVAP canister) in normal circumstances.
If, due to extreme conditions, excessive pressure is generated inside the tank, the purge port opens up, allowing fuel vapor to escape to the atmosphere, and stabilizes pressure inside the fuel tank. The evaporative emission valve has a head valve which prevents the fuel tank from overfilling during refueling operation. The evaporative emission valve also has a spring supported float assembly, which prevents liquid fuel from entering the vapor delivery line during severe handling, steep grades or in the event of vehicle rollover

 

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does it have a body lift if so make sure the fill hose is not kinked up. check vent on fill line. there are some different size tanks out there. may be a bad ground for the gauge or bad sending unit.
 

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yo,
Had to re-load and then re-start pc

Fuel Level Sender & Gauge Wiring for '92-96 Broncos ('87-96 F-series & Bronco similar)
IF THE IMAGE IS TOO SMALL, click it.
by Steve83 @ http://www.supermotors.net/registry/media/744437
Sender Range: 160 (full) - 16 (empty) Ohms
A gauge that pegs past full indicates an open circuit (broken wire; unplugged connector; corroded terminal; burned sender) on the Y/W wire.
A gauge that pegs past empty indicates a short to ground (pinched to the frame, body, or dash supports) on the Y/W wire, OR a sunk float. A gauge anywhere in between that doesn't move indicates an open circuit (blown fuse; corroded terminal) on the power (battery) side of the gauge OR a bad instrument cluster ground at C251 pin 9.

The terminals of C251 (& C250) are known to corrode & lose contact (open). Polish both the connector pins AND the film circuit pads with brown paper or a pink eraser.

The larger version of C441(WPT454) was used until '93.

The level sender can usually be disassembled & repaired by bending the wiper arm inside the plastic housing to apply slightly more force.


For more info, see this album's captions

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Full = 145 Ohms; Empty = 22.5 Ohms
 

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Ground Locations & Diagrams in 92-96; (pump and fuel level sender share connector C441 @ rear cross member) G100 @ LH front of engine compartment on upper radiator support & G200, Instrument Cluster ground is inside passenger side kick panel
 

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The splashing is strictly a problem with the filler neck - it's common for the inner hose to soften (especially if the truck is abandoned for a few years, and the gas sours) & collapse, restricting the inflow.

The gauge error indicates high resistance in the level sender circuit (Y/Wh). My first guess would be the instrument cluster film circuit terminals. Remove the cluster, and polish all the terminals with brown paper or a pink eraser. For more info, read these captions:

.
 
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