Lack/Loss Of Power - Mazda B-Series 1997 Workshop Manual

FT
TROUBLESHOOTING GUIDE
1
DESCRIPTION
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Performance poor under load (i.e.. power down when climbina hills)
1
13
(
STEP
/
INSPECTION
1
ACTION
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LACKILOSS OF POWER
/
ACCELERATIONICRUISE
Are any diagnostic trouble codes displayed during
Key On Engine Off, Key On Engine Running or Check for cause (refer to Diagnostic Trouble Code
Continuous Memory inspection? chart)
=
page FT-71
Go to next step
Check PID values of the following:
DPFEGR sensor
ECT sensor
IAC solenoid
LONGFTltLONGFT2
VPWR
VREF
Yes
-
page FT-74
Are PID values within specification?
Go to next step
No
[
3
1
Perform Fuel Line Pressure Inspection. Yes
(
Go to next step
1
Repair or replace poor connection in circuit or
component as necessary
I I
Is fuel line pressure correct?
=
page FT-l N o r low:
Check pressure regulator diaphragm
Fuel line pressure:
240-280 kPa (2.5-2.8 kgflcm2, 35-40 psi)
-
page FT-154
Check fuel pump circuit
=
page FT-151
High:
Check pressure regulator for high pressure cause
=
page FT-154
Check for clogged fuel return line
4 Visually look for fuel leakage at injector O-ring,
L r e s s u r e regulator. and fuel line. Service as
1
necessary.
Check pressure regulator diaphragm condition
(
Perform Fuel Pressure Hold Inspection.
-
page FT-150
1 1
If condition is OK, check injector
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i
Does fuel line pressure hold?
If condition is not OK, replace pressure regulator
1
5
Disconnect inertia fuel shutoff switch connector. Yes
/
Go to next steo
I
Crank engine for 5 seconds. Does pressure drop
more than 34 kPa (0.35 kgf/cm2, 5 psi) by the end
of injector(s) at PCM connector
of 5 second crank cycle?
If resistance is OK, check as follows:
Injector dr~ve signal
Injector flow rate
PCM
If resistance is not OK, check for open in injector
circuit
Is strong blue spark visible at each disconnected
high-tension lead while cranking engine?
Yes
No
Check spark plugs for improper gap, cracks or worn
electrodes
Clean
or
replace as necessary
=
Section G
If OK, go to next step
Check as follows:
High-tension leads
-
Section G
Crankshaft position sensor
=
Section G
Camshaft position sensor
=
page FT-168,174,180
7
Is there a restriction or leak in exhaust system?
m=
page FT-156
MF1753-C1
Yes
No
Check exhaust system
w
page FT-156
Go to next step