Fuel system FORD FESTIVA 1991 Repair Manual

Back To Article
GENERAL INFORMATION
How To Use The Engine Perform ance Section - 1989 & Newer Models
* PLEASE READ THIS FIRST *
HOW TO USE THE ENGINE PERFORMANCE SECTION
Congratulations, you have purchased the most advanced automotive repair and service information available. This information can help you, as
a professional automotive technician, to maintain top vehicle performance, and correct driveability problems on today's high-tech vehicles.
For your convenience and ease in use, all of our engine performance service and repair information is consistently organized by manufacturer,
using a progressive diagnostic/workflow approach. Due to the differences in how each manufacturer approaches diagnosis and repair, once
started and inside of an article, that manufacturer may drive the workflow in a direction other than what is outlined here.
The progressive diagnostic/workflow of our data is as follows:
APPLICATION to identify vehicle and system usage.
EMISSION APPLICATION to identify emission system usage.
SPECIFICATIONS to quickly find an engine performance service specification.
ADJUSTMENTS to perform engine performance related routine adjustments.
THEORY & OPERATION to familiarize yourself with new systems and technologies.
BASIC DIAGNOSTIC PROCEDURES located under TESTING & DIAGNOSTICS, also referred to as BASIC TESTING, is used for
performing a basic vehicle inspection and is also the starting point for diagnosis of a "no-start" condition.
SELF-DIAGNOSTICS located under TESTING & DIAGNOSTICS, also referred to as TESTS W/CODES, is where manufacturer
specific procedures for retrieving, identifying and diagnosing DTCs (trouble codes) retained in a control modules memory are located.
TROUBLE SHOOTING - NO CODES located under TESTING & DIAGNOSTICS, also referred to as TESTS W/O CODES, is where
an engine performance problem that does not set a DTC can be potentially isolated through either a SYMPTOM or INTERMITTENTS
duplication procedure.
SYSTEM & COMPONENT TESTING located under TESTING & DIAGNOSTICS, also referred to as SYSTEM/COMPONENT
TESTS, once directed to this article, specific system and component tests can be performed to help isolate faulty component/system
prior to replacement.
PIN VOLTAGE CHARTS provide supplemental information to help determine correct control module input and output signals. Pin
charts may also be referred to as PID charts by some manufacturers.
SENSOR RANGE CHARTS help determine if a sensor is out of calibration. In some cases an out-of-calibration sensor will not set a
DTC (trouble code), resulting in difficult to diagnose driveability symptoms.
VACUUM DIAGRAMS help determine correct routing of vacuum hoses when reinstalling components or performing emission
inspections.
REMOVE, OVERHAUL & INSTALL provides procedures necessary for removing and installing engine performance related
components.
WIRING DIAGRAMS can be used to identify circuits, terminals, wire colors and components referenced in testing procedures. NEW
COLOR WIRING DIAGRAMS (system diagrams) provide an easy method of identifying and tracing circuits.
APPLICATION
INTRODUCTION/ENGINE/VIN ID
Here you will find out how to identify an engine by its Vehicle Identification Number (VIN). The manufacturer's MODEL COVERAGE chart
lists each model and engine option, the fuel system, ignition system and engine code. Engine serial number locations are also shown here, as
well as the VIN code breakdown. Using model lookup in conjunction with VIN and engine ID will identify application information necessary
for servicing vehicle and ordering parts.
EMISSION APPLICATIONS
EMISSION APPLICATION TABLES
Here you will find a chart listing what emission control devices apply to each model. This can be helpful when performing government-
required emissions inspections. For quick reference, major emission systems and devices are listed in bold type in the emission table. Sub
components are listed in light type.
SPECIFICATIONS
NOTE:T his article is generic in nature and all inform ation does not apply to all vehicles. For vehicle specific
inform ation, see the appropriate articles in the ENGINE PERFORMANCE category.
NOTE:T his article is generic in nature and all inform ation does not apply to all vehicles. For vehicle specific
inform ation, see the appropriate articles in the ENGINE PERFORMANCE category.
NOTE:T his article is generic in nature and all inform ation does not apply to all vehicles. For vehicle specific
inform ation, see the appropriate articles in the ENGINE PERFORMANCE category.
NOTE:T his article is generic in nature and all inform ation does not apply to all vehicles. For vehicle specific
inform ation, see the appropriate articles in the ENGINE PERFORMANCE category.
Page 1 of 3 MITCHELL 1 ARTICLE - GENERAL INFORMATION How To Use The Engine Performance Section - 1989 & Newer Models
3/10/2009 http://www.eautorepair.net/app/PrintItems.asp?S0=2097152&S1=0&SG=%7B9B990D68%2D660A%2D45E9%2D8F46%2DE
...

SERVICE & ADJUSTMENT SPECIFICATIONS
If you want a specification quickly, this is the place to look. Instead of hunting through a long article, we've separated out the important
specifications and arranged them into easy-to-use tables in a centralized location. You can find valuable information like spark plug wire
resistance, valve clearance, timing, firing orders, etc.
ADJUSTMENT
ON-VEHICLE ADJUSTMENTS
The ON-VEHICLE ADJUSTMENTS article contains the type of information that was previously thought of as TUNE-UP information.
Procedures for checking and adjusting valves, base ignition timing and idle speed are found in this section. Use this section in conjunction with
SERVICE & ADJUSTMENT SPECIFICATIONS for performing routine maintenance. Also, if you have a driveability problem, ensure all on-
vehicle adjustments are within specification before attempting further diagnosis.
THEORY & OPERATION
This article covers basic THEORY & OPERATION of engine performance-related systems and components. Before diagnosing vehicles or new
systems with which you are not completely familiar, read this article.
TESTING & DIAGNOSTICS
BASIC DIAGNOSTIC PROCEDURES/BASIC TESTING
The procedures listed in this article can help you avoid skipping a simple step early, like checking base timing, which could be costly in both
time and money later. This is also a potential starting point for diagnosis of a "no-start" condition. If all systems check out okay here, proceed
to SELF-DIAGNOSTICS/TESTS W/CODES or TROUBLE SHOOTING - NO CODES/TESTS W/O CODES article.
SELF-DIAGNOSTICS/TESTS W/CODES
Use this information to retrieve and interpret Diagnostic Trouble Codes (DTCs) accessed from the vehicle's self-diagnostic system. Once
information is retrieved, manufacturer diagnostic procedures are given to help pinpoint and repair computer system/component faults. Also
included are steps for clearing trouble codes once these faults are repaired. If there is a driveability symptom with no trouble codes set,
proceed to TROUBLE SHOOTING - NO CODES/TESTS W/O CODES article.
TROUBLE SHOOTING - NO CODES/TESTS W/O CODES
This is where to go when you have a problem that does not set a trouble code. It can help determine cause of problem using driveability
symptoms and intermittent testing procedures. Procedures in this information should lead you to a specific component or system test.
SYSTEM & COMPONENT TESTING
Here you will find various tests for engine performance systems and their components, such as air induction (turbochargers and superchargers),
fuel control, ignition control and emission systems.
PIN VOLTAGE CHARTS
These are supplied (when available from manufacturer) to quicken the diagnostic process. By checking pin voltages at the Powertrain Control
Module (PCM), you can determine if the PCM is receiving and/or transmitting proper voltage signals. Pin charts may also be referred to as PID
charts by some manufacturers.
SENSOR RANGE CHARTS
SENSOR OPERATING RANGE CHARTS
These are supplied (when available from manufacturer) to determine if a sensor is out of calibration. An out-of-calibration sensor may not set a
trouble code, but it may cause driveability problems.
VACUUM DIAGRAMS
NOTE:T his article is generic in nature and all inform ation does not apply to all vehicles. For vehicle specific
inform ation, see the appropriate articles in the ENGINE PERFORMANCE category.
NOTE:T his article is generic in nature and all inform ation does not apply to all vehicles. For vehicle specific
inform ation, see the appropriate articles in the ENGINE PERFORMANCE category.
NOTE:T his article is generic in nature and all inform ation does not apply to all vehicles. For vehicle specific
inform ation, see the appropriate articles in the ENGINE PERFORMANCE category.
NOTE:T his article is generic in nature and all inform ation does not apply to all vehicles. For vehicle specific
inform ation, see the appropriate articles in the ENGINE PERFORMANCE category.
NOTE:T his article is generic in nature and all inform ation does not apply to all vehicles. For vehicle specific
inform ation, see the appropriate articles in the ENGINE PERFORMANCE category.
NOTE:T his article is generic in nature and all inform ation does not apply to all vehicles. For vehicle specific
inform ation, see the appropriate articles in the ENGINE PERFORMANCE category.
Page 2 of 3 MITCHELL 1 ARTICLE - GENERAL INFORMATION How To Use The Engine Performance Section - 1989 & Newer Models
3/10/2009 http://www.eautorepair.net/app/PrintItems.asp?S0=2097152&S1=0&SG=%7B9B990D68%2D660A%2D45E9%2D8F46%2DE
...

Back To Article
GENERAL INFORMATION
Waveform s - Injector Pattern T utorial
* PLEASE READ THIS FIRST *
PURPOSE OF THIS ARTICLE
Learning how to interpret injector drive patterns from a Lab Scope can be like learning ignition patterns all over again. This article exists to
ease you into becoming a skilled injector pattern interpreter.
You will learn:
How a DVOM and noid light fall short of a lab scope.
The two types of injector driver circuits, voltage controlled & current controlled.
The two ways injector circuits can be wired, constant ground/switched power & constant power/switched ground.
The two different pattern types you can use to diagnose with, voltage & current.
All the valuable details injector patterns can reveal.
SCOPE OF THIS ARTICLE
This is NOT a manufacturer specific article. All different types of systems are covered here, regardless of the specific year/make/model/engine.
The reason for such broad coverage is because there are only a few basic ways to operate a solenoid-type injector. By understanding the
fundamental principles, you will understand all the major points of injector patterns you encounter. Of course there are minor differences in
each specific system, but that is where a waveform library helps out.
If this is confusing, consider a secondary ignition pattern. Even though there are many different implementations, each still has a primary
voltage turn-on, firing line, spark line, etc.
If specific waveforms are available in On Demand for the engine and vehicle you are working on, you will find them in the Engine Performance
section under the Engine Performance category.
IS A LAB SCOPE NECESSARY?
INTRODUCTION
You probably have several tools at your disposal to diagnose injector circuits. But you might have questioned "Is a lab scope necessary to do a
thorough job, or will a set of noid lights and a multifunction DVOM do just as well?"
In the following text, we are going to look at what noid lights and DVOMs do best, do not do very well, and when they can mislead you. As
you might suspect, the lab scope, with its ability to look inside an active circuit, comes to the rescue by answering for the deficiencies of these
other tools.
OVERVIEW OF NOID LIGHT
The noid light is an excellent "quick and dirty" tool. It can usually be hooked to a fuel injector harness fast and the flashing l igh t is e a sy t o
understand. It is a dependable way to identify a no-pulse situation.
However, a noid light can be very deceptive in two cases:
If the wrong one is used for the circuit being tested. Beware: Just because a connector on a noid light fits the harness does not mean it is
the right one.
If an injector driver is weak or a minor voltage drop is present.
Use the Right Noid Light
In the following text we will look at what can happen if the wrong noid light is used, why there are different types of noid lights (besides
differences with connectors), how to identify the types of noid lights, and how to know the right type to use.
First, let's discuss what can happen if the incorrect type of noid light is used. You might see:
A dimly flashing light when it should be normal.
A normal flashing light when it should be dim.
A noid light will flash dim if used on a lower voltage circuit than it was designed for. A normally operating circuit would appear
underpowered, which could be misinterpreted as the cause of a fuel starvation problem.
Here are the two circuit types that could cause this problem: NOTE:This is GENERAL inform ation. This article is not intended to be specific to any unique situation or
individual vehicle configuration. For m odel-specific inform ation see appropriate articles where
available.
NOTE:This is GENERAL inform ation. This article is not intended to be specific to any unique situation or
individual vehicle configuration. For m odel-specific inform ation see appropriate articles where
available.
Page 1 of 19 MITCHELL 1 ARTICLE - GENERAL INFORMATION Waveforms - Injector Pattern Tutorial
3/10/2009 http://www.eautorepair.net/app/PrintItems.asp?S0=2097152&S1=0&SG=%7B9B990D68%2D660A%2D45E9%2D8F46%2DE
...

Circuits with external injector resistors. Used predominately on some Asian & European systems, they are used to reduce the available
voltage to an injector in order to limit the current flow. This lower voltage can cause a dim flash on a noid light designed for full voltage.
Circuits with current controlled injector drivers (e.g. "Peak and Hold"). Basically, this type of driver allows a quick burst of
voltage/current to flow and then throttles it back significantly for the remainder of the pulse width duration. If a noid light was designed
for the other type of driver (voltage controlled, e.g. "Saturated"), it will appear dim because it is expecting full voltage/current to flow
for the entire duration of the pulse width.
Let's move to the other situation where a noid light flashes normally when it should be dim. This could occur if a more sensitive n o id l igh t is
used on a higher voltage/amperage circuit that was weakened enough to cause problems (but not outright broken). A circuit with an actual
problem would thus appear normal.
Let's look at why. A noid light does not come close to consuming as much amperage as an injector solenoid. If there is a partial driver failure
or a minor voltage drop in the injector circuit, there can be adequate amperage to fully operate the noid light BUT NOT ENOUGH TO
OPERATE THE INJECTOR.
If this is not clear, picture a battery with a lot of corrosion on the terminals. Say there is enough corrosion that the starter motor will not
operate; it only clicks. Now imagine turning on the headlights (with the ignition in the RUN position). You find they light normally and are
fully bright. This is the same idea as noid light: There is a problem, but enough amp flow exists to operate the headlights ("noid light"), but not
the starter motor ("injector").
How do you identify and avoid all these situations? By using the correct type of noid light. This requires that you understanding the types of
injector circuits that your noid lights are designed for. There are three. They are:
Systems with a voltage controlled injector driver. Another way to say it: The noid light is designed for a circuit with a "high" resistance
injector (generally 12 ohms or above).
Systems with a current controlled injector driver. Another way to say it: The noid light is designed for a circuit with a low resistance
injector (generally less than 12 ohms) without an external injector resistor.
Systems with a voltage controlled injector driver and an external injector resistor. Another way of saying it: The noid light is designed
for a circuit with a low resistance injector (generally less than 12 ohms) and an external injector resistor.
If you are not sure which type of circuit your noid light is designed for, plug it into a known good car and check out the results. If it flashes
normally during cranking, determine the circuit type by finding out injector resistance and if an external injector resistor is used. You now
know enough to identify the type of injector circuit. Label the noid light appropriately.
Next time you need to use a noid light for diagnosis, determine what type of injector circuit you are dealing with and select the appropriate
noid light.
Of course, if you suspect a no-pulse condition you could plug in any one whose connector fit without fear of misdiagnosis. This is because it is
unimportant if the flashing light is dim or bright. It is only important that it flashes.
In any cases of doubt regarding the use of a noid light, a lab scope will overcome all inherent weaknesses.
OVERVIEW OF DVOM
A DVOM is typically used to check injector resistance and available voltage at the injector. Some techs also use it check injector on-time
either with a built-in feature or by using the dwell/duty function.
There are situations where the DVOM performs these checks dependably, and other situations where it can deceive you. It is important to be
aware of these strengths and weaknesses. We will cover the topics above in the following text.
Checking Injector Resistance
If a short in an injector coil winding is constant, an ohmmeter will accurately identify the lower resistance. The same is true with an open
winding. Unfortunately, an intermittent short is an exception. A faulty injector with an intermittent short will show "good" if the ohmmeter
cannot force the short to occur during testing.
Alcohol in fuel typically causes an intermittent short, happening only when the injector coil is hot and loaded by a current high e n o u gh t o
jump the air gap between two bare windings or to break down any oxides that may have formed between them.
When you measure resistance with an ohmmeter, you are only applying a small current of a few milliamps. This is nowhere near enough to
load the coil sufficiently to detect most problems. As a result, most resistance checks identify intermittently shorted injectors as being normal.
There are two methods to get around this limitation. The first is to purchase an tool that checks injector coil windings under full load. The
Kent-Moore J-39021 is such a tool, though there are others. The Kent-Moore costs around $240 at the time of this writing and works on many
different manufacturer's systems.
The second method is to use a lab scope. Remember, a lab scope allows you to see the regular operation of a circuit in real time. If an injector
is having an short or intermittent short, the lab scope will show it.
Checking Available Voltage At the Injector
Verifying a fuel injector has the proper voltage to operate correctly is good diagnostic technique. Finding an open circuit on the feed circuit
like a broken wire or connector is an accurate check with a DVOM. Unfortunately, finding an intermittent or excessive resistance problem with
a DVOM is unreliable.
Let's explore this drawback. Remember that a voltage drop due to excessive resistance will only occur when a circuit is operating? Since the
injector circuit is only operating for a few milliseconds at a time, a DVOM will only see a potential fault for a few milliseconds. The remaining
90+% of the time the unloaded injector circuit will show normal battery voltage. NOTE:Som e noid lights can m eet both the second and third categories sim ultaneously.
Page 2 of 19 MITCHELL 1 ARTICLE - GENERAL INFORMATION Waveforms - Injector Pattern Tutorial
3/10/2009 http://www.eautorepair.net/app/PrintItems.asp?S0=2097152&S1=0&SG=%7B9B990D68%2D660A%2D45E9%2D8F46%2DE
...

BRAKE PAD WEAR INDICATOR
CATALYTIC CONVERTER
COOLANT (PROPYLENE-GLYCOL FORMULATIONS)
ELECTROSTATIC DISCHARGE SENSITIVE (ESD) PARTS
ENGINE OIL
FUEL PUMP SHUTOFF SWITCH
This switch stops flow of fuel to engine after a collision. The impact does not have to be great for switch to be triggered. Switch must be reset
after collision. Switch is located under left rear speaker in luggage compartment. Press button to reset switch.
FUEL SYSTEM SERVICE
HALOGEN BULBS
PASSIVE RESTRAINTS
RADIATOR CAP
RADIATOR FAN
WARRANTY INFORMATION
BASIC NEW CAR LIMITED WARRANTY
All parts of the vehicle, except tires, are covered against defects in factory-supplied materials and workmanship for 12 months or 12,000 miles, CAUT ION: Indicator will cause a squealing or scraping noise, warning that brake pads need replacem ent.
CAUT ION: Continued operation of vehicle with a severe m alfunction could cause converter to overheat, resulting
in possible dam age to converter and vehicle.
CAUT ION: T o avoid possible dam age to vehicle use only ethylene-glycol based coolants with a m ixture ratio from
44-68% anti-freeze. DO NOT use 100% anti-freeze as it will cause the form ation of cooling system
deposits. T his results in coolant tem peratures of over 300° F (149°C) which can m elt plastics. 100% anti-
freeze has a freeze point of only -8° F (-22°C).
CAUT ION: Propylene-Glycol Mixtures has a sm aller tem perature range than Ethylene-Glycol. T he tem perature
range (freeze-boil) of a 50/50 Anti-Freeze/Water Mix is as follows: Propylene-Glycol -26° F (-32°C) - 257° F
(125°C) Ethylene-Glycol -35° F (-37°C) - 263° F (128°C)
CAUT ION: Propylene-Glycol/Ethylene-Glycol Mixtures can cause the destabilization of various corrosion inhibitors.
Also Propylene-Glycol/Ethylene-Glycol has a different specific gravity than Ethylene-Glycol coolant,
which will result in inaccurate freeze point calculations.
WARNING:Many solid state electrical com ponents can be dam aged by static electricity (ESD). Som e will display a
warning label, but m any will not. Discharge personal static electricity by touching a m etal ground point
on the vehicle prior to servicing any ESD sensitive com ponent.
CAUT ION: Never use non-detergent or straight m ineral oil.
WARNING:Relieve fuel system pressure prior to servicing any fuel system com ponent (fuel injection m odels).
WARNING:Halogen bulbs contain pressurized gas which m ay explode if overheated. DO NOT touch glass portion
of bulb with bare hands. Eye protection should be worn when handling or working around halogen
bulbs.
CAUT ION: Before operating vehicle, securely fasten passive shoulder restraints to the em ergency release buckles.
T he buckle fits in only one way. Ensure to position it properly.
CAUT ION: Always disconnect the fan m otor when working near the radiator fan. T he fan is tem perature controlled
and could start at any tim e even when the ignition key is in the OFF position. DO NOT loosen or rem ove
radiator cap when cooling system is hot.
WARNING:Keep hands away from radiator fan. Fan is controlled by a therm ostatic switch which m ay com e on or
run for up to 15 m inutes even after engine is turned off.
CAUT ION: Due to the different warranties offered in various regions and the variety of after-m arket extended
warranties available, please refer to the warranty package that cam e with the vehicle to verify all
warranty options.
Page 6 of 9 MITCHELL 1 ARTICLE - MAINTENANCE INFORMATION 1988-93 MAINTENANCE Ford Motor Co. Maintenance Inform...
3/10/2009 http://www.eautorepair.net/app/PrintItems.asp?S0=2097152&S1=0&SG=%7B9B990D68%2D660A%2D45E9%2D8F46%2DE
...