Gilbarco pump troubleshooting, Wayne fuel dispenser troubleshooting.| How to repair gas station fuel pumps and fuel dispensers and other petrol station pumps brands

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This article explains the step-by-step procedures involved in Gilbarco pump troubleshooting, wayne fuel dispenser troubleshooting, Tokheim pumps and other gas station pumps, specifying the fault where necessary for a given gas station pump brand.

By the end of this article, you will have enough knowledge in gas pumps and dispenser troubleshooting and repair.

In maintenance and repair process, it is step by step process to identify the parts that have faults, the same applies to fuel dispenser troubleshooting.

The fuel dispenser and gas station pump are a combination of mechanical parts and electronic components, same failure may be caused by various faults. For example, not Fueling may be caused by various faults.

When a gas station pump is not working, this can be caused by numerous failures from external components like power supply to the fuel dispenser its self.

A fuel dispenser to operate well, it has to be well connected to the external equipment for example power supply, fuel pipes, fuel tank with fuel. Failure in these external equipment can cause failure of the gas pump. Therefore, before concluding that the faults are within the fuel dispenser one has to first make sure that the external equipment are OK.

Fuel dispenser or gas station pump not fueling may be caused by different faults, therefore one has to go through a series of checks to identify the fault and its cause. The following include faults and solution for gas station fuel pump and dispensers

Table of Contents

Parts of some of the different brands of gas station pumps

NOTE: Refer to the above pictures for the parts of the dispenser or gas pumps used below.
Pumps may differ in the appearance but the internal parts are similar, just the difference is in design. The knowledge required to repair different brands of pumps is similar.

Below are the ways to identify, judge, detect, notice and rectify faults and malfunctions in fuel dispensers and gas station pumps.

A. Fuel dispenser or gas station pump not fueling.

i) Driving belts is loose. (driving belt (V-belt) is not tight), this can cause the gas station fuel pump to stop fueling.

Replace the driving belt with a new one or tighten it if it is not worn out.

You can also use ideal pulley for tightening the driving belt if it is available, it is adjusted outwards to make the v-belt tight.

With time the driving belt wares out due to friction between the pulleys and the belts.

When the driving belt wares out frequently, check the alignment of the driving belt and the two pulleys. The belt should be well aligned to a void quick waring off or loosening quickly.

If the motor belt is checked ok, proceed to the next fault below.

ii) Ex motor wired reversely, this can cause the fuel dispenser or gas pump to stop fueling.

In this fault, the motor rotates in the opposite direction to that of the pumping unit suction direction. The motor should rotate the pumping unit in the same direction of the arrow indicated on the pumping unit.

If they are operated in the opposite direction the pumping unit cannot suck fuel from the fuel tank. The pumping unit suction direction is given by the manufacture, therefore cannot be changed but the motor direction can be changed by changing the sequence of wiring.

Therefore, change motor direction or get another motor that runs in the direction of the pumping unit
For the case of three phase motor interchange the phases then the motor will run in the opposite direction.
Read more how to change motor direction (3 phase)

How to change direction of a single phase motor

iii) Empty fuel tank

Empty fuel tank, this can cause the fuel dispenser or gas pump to stop fueling. If the fuel tank is empty, it can stop the fuel dispenser and gas pump from dispensing.

Check for the amount of fuel in the tank by using the dip stick which is well calibrated for that specific tank. If it is confirmed that the oil tank is empty or below the level of the dead stock, the fuel tank should be refilled to a point above the dead stock level.

After refilling, test the fuel dispenser by fueling or dispensing fuel in a container.

If the fuel level in the tank is above the dead stock level proceed to the next step below.

v) Faulty foot valve

A foot valve is a type of check valve that is installed at the bottom of the fuel suction pipeline inside an underground fuel tank.

Foot valve keep the pump primed, allowing fuel to flow in but not letting it to flow back out into the fuel tank.

A faulty foot valve can stop a gas pump to stop delivering fuel if it is blocked by debris, jammed or damaged due to rust. To solve this, the foot valve should either be cleaned well or replace with a new one.

vii) When the petrol pump underground tank ventilation is being blocked by debris.

This can also stop the fuel pump or dispenser to stop delivering fuel.

The fuel tank has to breath. In order to breath a vent pipeline must be open such that it can relieve booth vacuum and pressure. When fuel is being sucked from the fuel tank by the petrol pump a vacuum has to be relieved breathing in air from the atmosphere, if the vent pipe is blocked a vacuum is created in the fuel tank hence stopping the suction of fuel by the gas pump.

During off loading of fuel from a truck, the fuel tank has to breath out fumes and air which are inside the tank. such that fuel from the truck can occupy the space that has been occupied by air and fumes inside the tank. When the vent pipe or breather is blocked, during offloading of fuel from the truck, pressure builds up in the tank. This causes fuel to bounce back at the offloading point reducing the speed of offloading fuel from the truck.

When the ventilation is blocked, it should be cleaned using a air compressor. Compressor horse pipe should be long enough to reach the top end of the vent pipes or breather pipes.

Vent roses are removed from the vent pipe up

The union or flange in the fuel tank manhole which is connecting the vent pipeline to the tank is opened.

Remove the part of union or flange on the side of the vent pipeline and connect a ball valve at that point.

If a ball valve is not available, find a way of closing that opened end of the vent in the manhole.

Compressed air is pumped by the compressor up the vent pipe where the vent roses where removed.

Since the other end is closed by the ball valve, air pressure builds up in the vent pipe

After pressure building up, the ball valve is opened at once.

All the debris and other material blocking the breather or vent pipeline is removed by this high air pressure.

After unblocking the vent pipe, replace back the removed fittings on the vent line.

viii) Malfunction of gas station fuel pumping unit.

The following can cause the failure or malfunctioning of the gas station pumping unit, followed are the solutions.

When the pump shaft and pulley cannot rotate, this can be solved by;

Replacing the faulty pumping unit with a new one.
Repairing the gas station pumping unit. This involves opening the pumping unit, replace the worn-out parts like vane blades if it is a vane pump, gears for geared pumping units

If the pump is severely worn out replace (for vane pump, replace the inner and outer ring cover of the main shaft. For Gear pump, replace the inner or outer wheel).

When the overflow valve’s core and valve body have foreign objects or damage leading to internal leakages. Remove the foreign objects if any, if damaged replace with a new one.

When the pump filter is very dirty with a lot of foreign objects can stop the pumping unit from working.

This filter net should be removed and cleaned. If it is physically damaged replace with a new one.

If return valve cannot close tight in pump, so there is no vacuum formed. To solve this cleaning the dirt inside return valve or check floater in the valve.

When the discharge valve is rusty. clean it or replace.

Use of improper product, such as oil with moisture, causing inner components and parts of pump to freeze during low temperature. To solve this replace lubricant oil or repair pump.

ix) Faulty gas station pump flow meter or fuel dispenser metering unit

When the fuel dispenser metering unit is faulty, the fuel dispenser or gas pump cannot deliver fuel.

When the flow meter has jammed, uninstall it from the dispenser and open it.

If there is any foreign object remove it.

Check whether meter check valve is working normally, if faulty replace with new one.

Check the rotary valve, if damaged replace with new one

Rotate the metering shaft using pair of pliers to confirm whether it is rotating.

If it is completely jammed replace with new one.

After repairing service ensure that distribution valve is installed correctly, if not reinstall.

X) Faulty solenoid valve.

Malfunctioning of a solenoid valve can also stop the gas pump or fuel dispenser to stop delivering fuel.

This fault can be caused by the following;

When default of control circuit leading to solenoid valve cannot open, check and repair control circuit unit

This electronic board is called a power board or interface board, so this board should be removed and repaired or replace with a new one.

Solenoid valve failure can be caused by blockage of the valve membrane passage (diaphragm), this leads to failure of a solenoid valve to open or cannot have proper fuel flow. This can be solved by opening the solenoid valve and repairing it or replace with new one

xi) Failure or malfunctioning of fuel dispenser nozzle

Failure of the fuel nozzle can also lead to failure of the fuel dispenser or gas pump to deliver fuel, this malfunctioning can be solved by the following;

The nozzle may fail when the nozzle filter net or connector is being blocked, remove the nozzle from the horse. This is done using pipe wrench and adjustable spanner. After opening remove the nozzle filter and clean it then replace it.

It may also be caused by failure of Nozzle’s main or sub valve to open, this is repaired by opening the nozzle from the horse wash and clean these valve parts with fuel, then replace them back.

If the nozzle remained in off position, this is repaired by checking air tube inside the nozzle spout, see if it blocked and also check if self sealed spring is rotating normally.

If its condition is unrepairable replace with new nozzle spout

xii) Failure and malfunctioning of gas pump or fuel dispenser pulser sensor

A faulty pulser sensor can also stop the fuel dispenser from delivering fuel. A pulser’s usual fault is usually caused by jamming of the rotating shaft. This is repaired by dismantling then ensure good rotation or replace with a new pulser sensor

Leakage on the fuel pipes connecting the fuel dispenser to the fuel tank.

Check for any leakage of fuel on the pipe line mainly the joins

If there is any loose joint, tighten it.

Pressure test the fuel pipeline to check for any leakages. This is done on the fuel pipeline using a air compressor, compressor kit, pressure gauge, water and soap.

Disconnect the fuel dispenser from the fuel pipeline.
Connect the compressor kit to the fuel pipeline, then connect the pressure gauge.
Power the compressor and connect it to the other side of the compressor kit.
Mix soap and water to make lather, pour it in a bottle and make a small hole on the bottle top.
Switch on the compressor, compressed air should enter the fuel pipe line through the compressor kit
The pressure gauge measures the pressure in the pipeline, the pressure in the pipeline should raise up to 60psi 0r 40bars. This is read from the pressure gauge.
After attaining that pressure, the compressor is switched off and the pipeline with compressed air is left to stay for 15 -30 minutes
If the pipe line has no leakages the pressure should not decrease, it should remain 60psi
If it decreases check for points where air is passing by using lather made from soap and water
Pour this water to joints and the all pipeline, at points where it is leaking bubbles will form
If that point is not tight, tighten it. If the fitting used at that point is fault, remove it and put another
After rectifying the problem repeat the pressure test.
The pressure test should be passed this time round.
if the line is confirmed by using pressure testing that it has no leakage please proceed to the next step below.

B) Gas pump and fuel dispenser having slow flow rate of fuel when dispensing.

This applies to gas pump slow delivery of fuel

The slow gas pump can be caused by a number of issues on the gas pump, they include the following and how they can be fixed.

i) The driving belt may be too loose on the motor and the pumping unit pulley

The driving belt may be too loose on the motor and the pumping unit pulley leading to the slipping of the belt, this is fixed by tightening the driving belt. If the ideal pulley is present it helps in the tightening of the driving belt.

If the driving belt is worn out replace with a new one of the same size.

ii) Clogged or dirty fuel filters of the dispenser

Slow flow rate of fuel from the gas pump or dispenser can be caused by clogged or dirty fuel filters of the dispenser. This is fixed by removing filters and cleaning them. If damaged replace with new ones. Gas pump or dispenser filters should be changed after six months during preventive maintenance of the gas pumps and fuel dispensers

iii) Pipping connection between the fuel tank and gas pump may be having leakage.

This can be seen from the fuel indicator near the nozzle, it is a glass where fuel is seen while dispensing fuel into the vehicle. If air bubbles are seen in this indicator it shows that fuel is mixed with air.

Air can also be seen belching out from the vent tube or breather of the pump. This can be fixed by looking for joints on the product lines that are leaking and not tight then tighten them using Sealant, stag, hemp, shellac, thread tape and many other leakage sealing materials.

vi) Fuel tank don’t have proper air inlet flow

When the underground fuel tank ventilation is being blocked by debris. This can also lead to slow rate of delivering fuel from the petrol pump.

The fuel tank has to breath. In order to breath a vent pipeline must be open such that it can relieve vacuum during suction of fuel by the gas pump. When fuel is being sucked from the fuel tank by the petrol pump a vacuum has to be relieved breathing in air from the atmosphere, if the vent pipe is blocked a vacuum is created in the fuel tank hence leading to slow flow or stopping the suction of fuel by the gas pump

To fix this the vent pipe line has to be cleaned and all the debris blocking it removed

v) Faulty Solenoid valve can also lead to slow flow rate of fuel from the gas pump or dispenser.

This can be fixed by opening the solenoid valve, remove the diaphragm if damaged replace with new one. Also check the magnetic coil whether the magnet is created during fueling. This can be checked by putting a good magnetic material like Allen key into the holes of the coil to heck for presence of magnet when fueling.

If not present replace with new coil

Opening of the foot valve is too narrow

When the opening of the foot valve is too narrow can also cause slow flow rate of fuel delivered from a gas pump or fuel dispenser. The foot valve is found at the bottom of the suction line in the fuel tank. This can be fixed by cleaning the foot valve removing all the foreign materials blocking it or replace with a new foot valve with a wider opening.

vi) Malfunctioning of gas pump pumping unit or fuel dispenser pumping unit

This can also lead to the slow flow rate of fuel delivered into a car

The following can cause the malfunctioning of the pumping unit leading to slow flow rate and how it can be repaired;

The filter at the pumping unit may be very dirty leading to blocking of fuel hence it cannot suck well the fuel. This can be fixed by removing the pumping unit filters and cleaning them. If damaged replace them with new ones.
If the tension of the adjustable spring inside the overflow valve is too weak in the pump can also lead to the slow dispensing of fuel from the gas pump or dispenser.

This is repaired by opening the pumping unit, then adjust the screw adequately clock wise. Also add or replace gasket.

For a vane pumping unit, the vane blades with time can get worn out leading to slow delivery of fuel by the gas pump. When the blades are worn out, this causes loss of vacuum or little vacuum which is below the requirement. This is repaired by replacing the worn-out blades with new ones.

For geared pumping unit the inner and outer gear wear out with time leading to slow delivery of fuel from the petrol pump, this is repaired by replace new inner and outer gear of the pumping unit.

Over flow valve may be jammed or cannot seal tightly

Returning valve doesn’t close tightly in the pumping unit causing air to flow into low pressure chamber, so there is no vacuum.

vii) Malfunctioning of fuel dispenser flow meter

A faulty fuel dispenser flow meter can also lead to slow flow rate when deriving fuel to the vehicle

Usually, it is due to the driving shaft not turning smoothy causing reduced fuel flow

viii) Faulty fuel dispenser nozzle.

When the nozzle is faulty it can also lead to slow flow rate of fuel delivered by a dispenser. This is fixed by removing the nozzle from a hose pipe, then open it check the valve and the filters in the nozzle if any. If there is dirt or any foreign material remove and clean well or replace with a new one.

C. Fuel dispenser or gas pump having loud noise and strong vibration during dispensing of fuel

The following can cause the gas pump or fuel dispenser to produce loud noise and strong vibration during the delivery of fuel and how they can be repaired.

i) Increased work load on the pumping unit

The following can lead to increased work load on the gas station pump pumping unit.

When the opening of the foot valve inside a fuel storage tank is too small, this can be caused by dirt or debris blocking the foot valve. It should be remove and cleaned or replace with new one.
Too long pipe line can also increase work load on the pumping unit leading to the loud noise and vibration of the gas pump or fuel dispenser. This is solved by reducing on the length of fuel pipeline or installing a stronger pumping unit of a higher rating.
When a pipeline diameter is too small with many bends leading to increased work load on the gas pump’s pumping unit leading to loud noise and vibration
fuel pipeline with too many bends for example too many elbows in Fuel pipeline reduce the flow rate. so this bends should be minimized.

ii) Faulty gas pump or fuel dispenser pumping unit

Faulty gas pump or fuel dispenser pumping unit may also cause the loud noise and vibration produced by the fuel dispenser or gas pump. The faults may be due to the following and their solutions.

When filter net in the fuel pump is being blocked, this leads to insufficient supply of fuel to the fuel pump causing loud noise. This is fixed by cleaning filter net in the pumping unit removing all the dirt and debris. Or replace filter net
When vane blades jam for vane pump, the discharging beat frequency of fuel increases causing the gas pump or dispenser to produce loud noise
For geared pumping unit, when gears jam causes an increase in the discharging fuel frequency leading to the loud noise produced by the dispenser

When beat frequency of fuel being discharged is the same as with beat frequency of the fuel dispenser, also causes the dispenser to have loud noise and increase in vibration. This is fixed by adjusting the flow rate
When some components of the fuel dispenser or gas pump loosen, causes resonance in vibration leading to loud noise. This is fixed by tightening all lose bolts and nuts in the fuel dispenser, using rubber spacers.
When using three phase EX motor, when one phase is off or low voltage causes the ex-motor to rotate abnormally leading to loud noise and vibration. This is repaired by suppling the Ex-motor with all three phases and right voltage.

D) Fuel flowing out from the air vent of the gas station pump or fuel dispenser

The air vent is located in sides of the fuel dispenser or gas pump.

The importance of this air vent is to let out the air separated from the fuel by air separator located in the pumping unit.

The following are the causes of fuel flowing from the air vent and how it can be fixed;

When using above ground fuel storage tanks (high rack or semi rack storage tanks). Just block the air vent hole.
Floater in the air separator located in the pumping unit cannot float or float back to the designated position. Ie. The floater is stuck. Fix or replace with new floater.
Air sucked through a leaking pipe may result into air fuel mixture coming out of the air vent. This is fixed by tightening that leaking point on the line.
When fueling operations are started often but not fueling can also cause fuel flowing out from air vent.

E) Air and fuel not clearly separated.

There is a leakage along the pipe line or inside the low-pressure camber of fuel pumping unit.
Return valve is under open state, and linked with atmospheric pressure.
Discharge valve of the pump is under open state, causing large amount of air flow into the flow meter together with fuel. This is fixed by dismantling the discharge valve and clean it, ensure that the valve core can have agile movement.

F) Inconsistent of fuel flow from the gas pump or dispenser during fueling or dispensing into the car

Filter net with in fuel pump is too dirt. This is fixed by removing and cleaning it.
Product pipeline have shape bending, causing air to be trapped within the high end of pipe leading to inconstancy of fuel flow during fuel delivery. This is fixed by revising the pipe work.
Air vent of fuel storage tank has obstruction, especially for petrol. This is fixed by increasing the height of air vent to a height of more than 4 meters, or clean the air vent nozzle for clear air passage.

G) Poor accuracy in measurement of fuel by the gas pump or fuel dispenser

This can lead to over delivery of fuel or under delivery of fuel. This can be caused by the following

Bad leakage within the flow meter leading to poor accuracy. This can be fixed by replacing a new metering unit
Poor air and fuel separation, causing delivery of fuel containing air vapor. This is fixed by repairing the floater in the pumping unit
Dividing disc of the pulser sensor is loose or double beam light is damaged. This is fixed by tightening the diving disc of the pulser sensor or replace with new pulser.
Computer main board is damaged or when main board is replaced is not compatible with the flow meter.

H) Difficulty in starting the ex-motor of the gas pump or fuel dispenser.

Ex motor is overloaded, main cause is pumping unit jamming. This is fixed by dismantling the pumping unit followed by greasing the rotating part, replace any faulty part.
Solid state relay is damaged, causing difficulty in starting Ex motor or heating up. This is fixed by replacing the solid-state relay. There are gas pumps or fuel dispensers that use electrical contractors instead of solid-state relay, replace this contractor if faulty.
External wiring faults may also cause ex motor rotate slowly or heating up, for example one phase missing for three phase motors, low voltage, diameter of wire is too small, long wiring distance.
Faulty start capacitor of the ex-motor. When the capacitor is faulty dismantle the motor and replace the start capacitor with a new one of the same micro faraday (MF).

Check also the run capacitor if it is working well.

Ex motor is faulty, if the motor windings are burnt, take for rewinding or replace with new Ex motor.

I) Fuel flows normally from the gas pump or fuel dispenser but there is no counting on the screen or display.

Axle pin on driving shaft of the metering unit is broken. This is fixed by replacing it with new one
Axle pin of pulser sensor is broken or screw for driving disc has loosen. This is fixed by repairing and tightening.
wiring connection between computer board and pulser sensor is loose or broken. If it is broken replace with a new wire connector. If loose tighten it.
Double beam light circuit is damaged. Replace with new pulser sensor.
Computer main board is damaged this is fixed by replacing the main computer board.

J) Fuel dispenser or gas pump doesn’t start up

External source is off or no power supply. Check the power supply.
Nozzle switch is damaged. Fixed by repairing nozzle switch or replacing it.
Connection between keypad and computer is loose. This is fixed by tightening it by plugging it in harder.
Circuit on the computer main board which is controlling the ex-motor and solenoid valve has fault. This is fixed by replacing computer board.
Ex motor is damaged. Repair the motor or replace with new one
Solid state relay has fault. Fixed by replacing the relay.
Power board may be supplying unstable power (voltage) to main computer board. This is fixed by replacing computer board.

K) Fuel dispenser motor doesn’t stop running.

Nozzle holder switch is damaged. This is fixed by replacing the switch
Stop key on the keypad is faulty. Fixed by replacing keypad.
Solid state relay or contactor is faulty. This is fixed by relacing solid state relay or contactor.
Circuit on the computer board which control ex motor and solenoid valve has fault. Fixed by repairing computer board or replacing computer board.
During preset fueling. When reaching preset value and fuel dispenser doesn’t stop, this fault is with the main computer board.

L. Ex motor of the gas pump or fuel dispenser often stops during dispensing or fueling.

When the motor often stops during fueling, the problem could be with the external power supply which is not stable. This is fixed by repairing the external power supply.
A faulty power board supplying unstable power to computer board can also cause this problem. This is fixed by replacing the board with a new one.
When the solid-state relay or contactor supplying power to the motor is faulty. This is fixed by replacing the solid-state relay or contactor.
Circuit on the main board which control the ex-motor and solenoid valve has fault. Fixed by replacing the main board.

M) Fueling process for gas pump or fuel dispenser Dis normal, but display board do not display fueling data

This can be both sides or one side.
1. connection between display board and main board loosened. This is fixed by tightening the connection.
2. Display board is damaged. Fixed by replacing display board.
3. Computer board is faulty.

N) Solenoid valve cannot open or no flow during preset fueling or dispensing

Circuit controlling solenoid valve has fault
Faulty solenoid valve
Amount setting for advance shut off is so small, causing no small flow during preset shutoff.
The connection wiring for high flow and small Low flow valve is connected wrongly causing no slow flow during preset fueling.
Dirt inside the solenoid valve, leading to failure for the valve to close. This is fixed by cleaning the dirt away

O) Fuel dispenser or gas pump has electric leakage, when you touch it you get electric shock.

When fuel dispenser and gas pump have electric leakage or electric shock, it can easily cause fire and personal injury. If the leakage is detected the gas pump or dispenser must be immediately disconnected from the power supply and stop using the dispenser until leakage problem is solved.
Insulation of the coil wire of the ex-motor has damage, causing leakage. This is fixed by replacing Ex motor.
External connection wire has torn insulation and contacts with metal structure of the fuel dispenser. This is fixed by insulating the torn wire with insulating tape or replace wire.
Surrounding environment dampness or the insulation capacity of the wire connecting board reduced
There is no reliable earthing for dispenser or there is no leakage protection circuit. This is fixed by earthing the gas pump or fuel dispenser and connection of a leakage protection circuit.

1 thought on “Gilbarco pump troubleshooting, Wayne fuel dispenser troubleshooting.| How to repair gas station fuel pumps and fuel dispensers and other petrol station pumps brands”

James
June 1, 2023 at 4:30 pm

This information is Very very helpfull to me .Pleas i have a problem with my ….The pump motor runs ok but the fuel does not come out off the nozzle .
Pleas what would be the cause of it can u help me out…thankyou.
Pleas i would like to here from you soon..