190203d Fuel System Service Flashcards by HET2 SAIT

So far the only highway vehicle with a final stage filter is a Mack truck. What are four things you can list about a final stage filter?

Extremely fine filtration, located just before injection pump, subject to positive pressure and used only with certain types of pumps (single plunger distributor type)

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Fuel filters are rated according to their ability to stop certain sized particles measured in

Microns
One grain of table salt is 100 µm
One strand of human hair 70 µm
Smallest particle visible to the human eye 40 µm
One grain of talcum powder 10 µm

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What are three things you can say about a transfer pump in their operation

They are all relatively low pressure pump, they move fuel from the fuel tank to the injection pump or unit injectors.

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What are five basic types of fuel transfer pumps

Diaphragm, plunger, hand primer, gear and vane/blade.

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Diaphragm pumps are used by some manufacturers as a…

Lift pump to provide a steady volume of fuel to a vane type transfer pump(in integral part of the injection pump)

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What are two methods of operating a diaphragm pump

Off the engine or injection pump camshaft

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True or false. Diaphragm pumps will work with the cam turning in either direction.

True

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What is the self regulating mechanism in a diaphragm pump.

Diaphragm spring tension controls maximum fuel pressure.

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What pressure to diaphragm pumps normally operate at (max)

Output usually limited to 10 psi maximum

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Does a diaphragm pump produce a smooth or pulsating output

Pulsating

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True or false. Diaphragm pumps may include a sediment and/or water separator?

True

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If a diaphragm pump has a built-in hand primer and does not seem to be priming what may be the issue

The lever inside the engine may be high on the camshaft eccentric. You may need to rotate engine to bring the lever down

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Fuel flow through the plunger type pump is controlled by what

A set of check valves and spring pressure will determine the fuel pressure

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Name the components of a plunger pump body

Roller tappet, plunger push rod, plunger, plunger spring, spring cap

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What are hand primer pumps used for

To manually bleed primary fuel system after air is admitted

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True or false

Are all fuel systems equipped with hand primers

False

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What must be done with the plunger when pumping process is completed

Make sure to seat the plunger and lock the shaft to keep foreign material out

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Where can a gear type pump be mounted

Integral part of a fuel pump assembly or mounted and driven by the engine gear train

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As a get pump rotates where dose the low pressure or vacuum develop

Inlet side

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True or false

Gear pumps must have a set screw to slow rotation when maximum pressure is reached

False.

Pressure relief is used

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Vane or Type pumps are commonly used in single or opposed plunger distributor type fuel injection pumps as an integral transfer pump

Blade

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A operation of a vane type pump are

May be assembled for bi-directional rotion
Will produce high pressure
A positive displacement
Smooth output with limit pulsation

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Fuel filters filter what size partials ?

Microns

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List four kind of basic fuel filters.

screen / strainer
surface
depth
edge

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How do surface filters remove contaminates from the fuel ?

By not allowing partials larger than the filter medium to pass through it.

Three common filter classifications are...

1. primary 2. secondary 3. final stage

Fuel system contamination happens most often when ?

Refuelling or fuel filter maintenance.

Fuel drained from the system during filter maintenance should be...

Disposed of in an environmentally friendly manner.

During new filter installation what two things can be done to prevent system contamination ?

1. use the system hand pump to fill the new installed empty filter. 2. fill new filter with clean filtered fuel before installation.

After installation of a new fuel filter the engine runs rough, why ?

Air in the fuel system.

Five basic types of fuel transfer pumps are?

1. diaphragm 2. plunger 3. hand primer 4. gear 5. vane or blade.

Diaphragm & plunger pumps are operated by ?

An eccentric on the engine or fuel injection pumps camshaft.

Gear & vane ( blade ) style pumps are positive displacement. So they must have a to control max system pressure.

Pressure relief valve

Why must a hand pump be seated & locked ( threaded ) in place ?

To prevent contamination of the fuel system & prevent fuel leakage while the engine is running.

Why don't diaphragm & plunger pumps need a pressure relief valve ?

Spring pressure limits the max pressure these pumps can develop.

Gear & vane (blade) pumps are alike, why ?

Both have a specific direction of rotation.

Before testing or diagnosing any fuel system what first should be checked ?

Fuel tank level(s)

The correct amount of fuel flow is important to ensure?

A sufficient volume of fuel for injection pump and sufficient cooling of system components

What is a special tool for testing flow in a system called?

Flowmeter

Low fuel volume could be the result of?

High inlet restriction, restricted fuel line, a plugged fuel filter, a worn transfer pump

Air in the fuel system could be the result of?

A cracked or broken fuel tank strand pipe, loose fit fittings, cracked fuel lines or hoses, missing gaskets or O-rings in the primary fuel filter assembly

For every 5.5°C (10°F) above 37.8°C (100°F) engine power decreases by how much?

Diaphragm pumps are inexpensive dependable units that can tolerate _______ and _____ with very little damage.

Abrasives and water

Plunger type pumps have closely fitted components that will not tolerate _______ or _______ In a fuel system.

Abrasive material or water

List five problems that could cause hard starting

Low fuel level, restricted inlet (plugged), cracked or loose inlet pipes or hoses, plugged filter before pump and fuel system draining back to tank after shutdown

Why select fuel system test gauges that ranges twice the pressure being measured

To ensure accurate test readings and protect the gauge from possible damage

What are you testing for when you install a gauge between the fuel supply tank and the transfer pump inlet on running engine

You are checking inlet restriction

What are the two basic methods for testing fuel system volume

Measure the volume of fuel flow with the engine running at a specific RPM and measure the output volume of the fuel pump while the engine is cranking

What are four problems that could cause low fuel system volume

Hi inlet restriction,restricted fuel lines, a plugged fuel filter, a worn transfer pump

What units of measurement are commonly used when testing inlet restriction

Inches of mercury or millimeters of mercury

How do you test fuel pressure

On a running engine install a gauge on the outlet side of the transfer pump after the secondary filter

What are four possible causes of air entering the fuel system

Cracked or broken fuel tank standpipe, loose fittings, cracked fuel lines or hoses and missing gaskets or O-rings in the primary fuel filter assembly

Sealed feel pump should not be disassembled unless you have what three things

Proper training, a clean environment and the correct tools

Fuel leaking from the vent all of the diaphragm type pump would be caused by

Torn or leaking diaphragm

A plunger type pump with the week or broken plunger spring would have

Low volume or pressure

It's a gear or vane pump had a broken pressure relief spring what effect with this have on the fuel system

A broken pressure relief spring would cause low fuel pressure

What three clearances should be checked when inspecting a gear type transfer pump

Gear to gear, gear to pump body, gear to cover

What five areas of a vane type pump should be checked for wear

end and the side of the vanes, rotor slots, inside surface of the liner and endplate or cover

7 test that can be done on the fuel supply system, these tests can reveal engine problems as?

Hard starting Stalling Rough running Low power

Symptoms that could cause a Hard Start could be

``` Low fuel level Restricted inlet Plugged fliter (before pump) Cracked or lose inlet pipes Fuel draning back to tank after shut down ```

Symptoms that could relate to engine stalling are?

Low fuel level Restricted inlet Cracked or lose inlet pipeing Plugged fuel filter, ( before or after pump)

A symptom of a rough running could be?

Low fuel level | Aerated filter

Symptom of a engine with low power could be

``` Low fuel level Low fuel pressure Low fuel volume High inlet restrictions Plugged fuel filters Restriction in fuel lines Poor fuel quality ```

When testing the fuel system, for maximum accuracy gagues should be selected with a range no greater than?

Twice the pressure being measured

To test inlet restriction install a ______ | As close as possabile to the _________

Vacuum gauge Transfer pump inlet

A high inlet restriction could be the result of?

Plugged tank vent Restricted fuel lines Plugged filter before the pump

When the timing pin in the front gear cover it fits into a hole in the cam shaft drive gear, when timing pin is installed , the engine has to be at?

At TDC on the compression stroke.

2 company's that manufacture opposed plunger pumps are?

Stanadyne (roosa master) and Lucas (CAV)

Oppposed plunger pumps are also called?

Rotary or distributor, cause the injector out lets are arranged to specific number of degrees apart in a circular pattern according to firing order.

Identify three factors that affect the operation of the fuel injector and have a negative influence on fuel injectors service life.

water heat dirt

List three clearance that should be checked when inspecting a gear type transfer pump?

gear to gear clearance gear to pump body clearance gear to body cover clearance

List five areas of a vane pump that should be checked for wear?

``` ends of the vanes sides of the vanes rotor slots inside surface of the ring end plate or cover ```

What is the approximate transfer pressure for a EUP system?

70 psi

both gear and vane transfer pumps are positive displacement and must have a __________ to control maximum fuel system pressure.

relief valve