fuel pressure ISUZU TF SERIES 2004 Repair Manual

6E–340 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
DIAGNOSTIC TROUBLE CODE (DTC) P1630 (SYMPTOM CODE A)
(FLASH CODE 51) FUEL INJECTION QUANTITY CIRCUIT MALFUNCTION
DIAGNOSTIC TROUBLE CODE (DTC) P1630 (SYMPTOM CODE B)
(FLASH CODE 51) FUEL INJECTION QUANTITY CIRCUIT MALFUNCTION
Condition for setting the DTC and action taken when the DTC sets
Circuit Description
The ECM is calculates an injection quantity and an
injection timing using the various sensors. And the PSG
controls the high pressure solenoid valve depending onprogrammed pump map data.
Flash
CodeCode Symptom
CodeMIL DTC Name DTC Setting Condition Fail-Safe (Back Up)
51 P1630 A ON Fuel Injection Quantity Circuit
Malfunctio nThe PSG (pump control unit)
de te cts high pressure sole-
no id v alve contro l circuit ma l-
function due to high curre nt.Fuel inje ctio n qua ntity is
reduced.
B ON Fuel Injection Quantity Circuit
Malfunctio nThe PSG (pump control unit)
de te cts high pressure sole-
no id v alve contro l circuit ma l-
function due to co ntinuo us
curre nt.1. MAB (fuel cutoff solenoid
valve) is operated.
2. Desired injection quantity
becomes 0mg/strk.

6E–364 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
17 Remove the eye bolt with gauze filter from the
injection pump and check for the following conditions.
Objects blocking at the gauze filter. Check for a
condition that causes contaminated fuel, such as
the customer is using an aftermarket fuel filter or
ex tended maintenance interval.
Check for a condition that causes fuel wax ing or
icing, such as the customer is using an incorrect
fuel type in winter season or water mix ed with the
fuel.
If a problem is found, repair as necessary.
Was the problem found?
—Replace the
eye bolt with
gauze filter and
verify repair Go to Step 18
18 Check the engine compression pressure for each
cylinders.
If a problem is found, repair as necessary.
Was the problem found?
More than 2.1
Mpa (21.0 kg/
cm
2) Verify repair Go to Step 19
19 If the injection pump was replaced, are the timing
gears or injection pump correctly installed?
—Go to Step 20Repair as
necessary Step Action Value(s) Yes No

6E–368 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
15 Remove the eye bolt with gauze filter from the
injection pump and check for the following conditions.
Objects blocking at the gauze filter. Check for a
condition that causes contaminated fuel, such as
the customer is using an aftermarket fuel filter or
ex tended maintenance interval.
Check for a condition that causes fuel wax ing or
icing, such as the customer is using an incorrect
fuel type in winter season or water mix ed with the
fuel.
If a problem is found, repair as necessary.
Was the problem found?
—Replace the
eye bolt with
gauze filter and
verify repair Go to Step 16
16 Remove the injection nozzles from the engine and
check for the following conditions.
Improper splay condition.
Operating pressure is incorrect.
If a problem is found, repair as necessary.
Was the problem found?
—Replace the
injection nozzle
and verify repair Go to Step 17
17 Check the engine compression pressure for each
cylinders.
If a problem is found, repair as necessary.
Was the problem found?
More than 2.1
Mpa Verify repair Go to Step 18 Step Action Value(s) Yes No
1st Stage 2nd Sta ge
4JA1-TCApproximatly
19.0 MpaApprox ima tly
33.5 Mpa
4JH1-TCApproximatly
19.5 MpaApprox ima tly
33.8 Mpa

6E–374 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
26 Using the Tech 2 or the vacuum pump and check the
EGR valve operation for the following condition
through the small window.
ÅERestrict shaft movement. Check for objects sticking
the shaft, broken diaphragm or ex cessive carbon
deposit.
Tech 2:
1. Using the Tech 2, ignition "On" and engine "On".
2. Select the "Miscellaneous Test" and perform the
"EGR Solenoid Test" in the "Solenoid".
3. Operate the Tech 2 in accordance with procedure.
Solenoid 95%: EGR Valve Open
Solenoid 5%: EGR Valve Close
Vacuum Pump:
1. Using the vacuum pump. Disconnect the original
vacuum hose and connect the hose to the EGR
valve.
2. Apply vacuum pressure.
Vacuum Apply: EGR Valve Open
Vacuum Release: EGR Valve Close
If a problem is found, repair as necessary.
Was the problem found?—Verify repair Go to Step 27
27 Check the ex haust system for a possible restriction.
Damaged or collapsed pipes or catalytic converter.
Internal muffler failure.
If a problem is found, repair as necessary.
Was a problem found?—Verify repair Go to Step 28
28 Visually/physically inspect for the following conditions.
Restrict fuel supply system. Check for a pinched
fuel hose/pipe.
Check for a condition that causes fuel wax ing or
icing, such as the customer is using an incorrect
fuel type in winter season or water mix ed with the
fuel.
If a problem is found, repair as necessary.
Was a problem found?—Verify repair Go to Step 29
29 Replace the fuel filter.
Was the problem solved?—Verify repair Go to Step 30 Step Action Value(s) Yes No

Vacuum Pump Small Window

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–375
30 Remove the eye bolt with gauze filter from the
injection pump and check for the following conditions.
Objects blocking at the gauze filter. Check for a
condition that causes contaminated fuel, such as
the customer is using an aftermarket fuel filter or
ex tended maintenance interval.
Check for a condition that causes fuel wax ing or
icing, such as the customer is using an incorrect
fuel type in winter season or water mix ed with the
fuel.
If a problem is found, repair as necessary.
Was the problem found?
—Replace the
eye bolt with
gauze filter and
verify repair Go to Step 32
31 Remove the injection nozzles from the engine and
check for the following conditions.
Improper splay condition.
Operating pressure is incorrect.
If a problem is found, repair as necessary.
Was the problem found?
—Replace the
injection nozzle
and verify repair Go to Step 32
32 Check the engine compression pressure for each
cylinders. Each cylinder must be evenly.
If a problem is found, repair as necessary.
Was the problem found?
More than 2.1
Mpa Verify repair Go to Step 33 Step Action Value(s) Yes No
1st Stage 2nd Sta ge
4JA1-TCApproximatly
19.0 MpaApprox ima tly
33.5 Mpa
4JH1-TCApproximatly
19.5 MpaApprox ima tly
33.8 Mpa

6E–380 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
24 Using the Tech 2 or the vacuum pump and check the
EGR valve operation for the following condition
through the small window.
ÅERestrict shaft movement. Check for objects sticking
the shaft, broken diaphragm or ex cessive carbon
deposit.
Tech 2:
1. Using the Tech 2, ignition "On" and engine "On".
2. Select the "Miscellaneous Test" and perform the
"EGR Solenoid Test" in the "Solenoid".
3. Operate the Tech 2 in accordance with procedure.
Solenoid 95%: EGR Valve Open
Solenoid 5%: EGR Valve Close
Vacuum Pump:
1. Using the vacuum pump. Disconnect the original
vacuum hose and connect the hose to the EGR
valve.
2. Apply vacuum pressure.
Vacuum Apply: EGR Valve Open
Vacuum Release: EGR Valve Close
If a problem is found, repair as necessary.
Was the problem found?—Verify repair Go to Step 25
25 Visually/physically inspect for the following conditions.
Restrict fuel supply system. Check for a pinched
fuel hose/pipe.
Check for a condition that causes fuel wax ing or
icing, such as the customer is using an incorrect
fuel type in winter season or water mix ed with the
fuel.
If a problem is found, repair as necessary.
Was a problem found?—Verify repair Go to Step 26
26 Replace the fuel filter.
Was the problem solved?—Verify repair Go to Step 27 Step Action Value(s) Yes No

Vacuum Pump Small Window

6E–386 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
24 Using the Tech 2 or the vacuum pump and check the
EGR valve operation for the following condition
through the small window.
ÅERestrict shaft movement. Check for objects sticking
the shaft, broken diaphragm or ex cessive carbon
deposit.
Tech 2:
1. Using the Tech 2, ignition "On" and engine "On".
2. Select the "Miscellaneous Test" and perform the
"EGR Solenoid Test" in the "Solenoid".
3. Operate the Tech 2 in accordance with procedure.
Solenoid 95%: EGR Valve Open
Solenoid 5%: EGR Valve Close
Vacuum Pump:
1. Using the vacuum pump. Disconnect the original
vacuum hose and connect the hose to the EGR
valve.
2. Apply vacuum pressure.
Vacuum Apply: EGR Valve Open
Vacuum Release: EGR Valve Close
If a problem is found, repair as necessary.
Was the problem found?—Verify repair Go to Step 25
25 Check the ex haust system for a possible restriction.
Damaged or collapsed pipes or catalytic converter.
Internal muffler failure.
If a problem is found, repair as necessary.
Was a problem found?—Verify repair Go to Step 26
26 Visually/physically inspect for the following conditions.
Restrict fuel supply system. Check for a pinched
fuel hose/pipe.
Check for a condition that causes fuel wax ing or
icing, such as the customer is using an incorrect
fuel type in winter season or water mix ed with the
fuel.
If a problem is found, repair as necessary.
Was a problem found?—Verify repair Go to Step 27
27 Replace the fuel filter.
Was the problem solved?—Verify repair Go to Step 28 Step Action Value(s) Yes No

Vacuum Pump Small Window

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–393
26 Using the Tech 2 or the vacuum pump and check the
EGR valve operation for the following condition
through the small window.
ÅERestrict shaft movement. Check for objects sticking
the shaft, broken diaphragm or ex cessive carbon
deposit.
Tech 2:
1. Using the Tech 2, ignition "On" and engine "On".
2. Select the "Miscellaneous Test" and perform the
"EGR Solenoid Test" in the "Solenoid".
3. Operate the Tech 2 in accordance with procedure.
Solenoid 95%: EGR Valve Open
Solenoid 5%: EGR Valve Close
Vacuum Pump:
1. Using the vacuum pump. Disconnect the original
vacuum hose and connect the hose to the EGR
valve.
2. Apply vacuum pressure.
Vacuum Apply: EGR Valve Open
Vacuum Release: EGR Valve Close
If a problem is found, repair as necessary.
Was the problem found?—Verify repair Go to Step 27
27 Visually/physically inspect for the following conditions.
Restrict fuel supply system. Check for a pinched
fuel hose/pipe.
Check for a condition that causes fuel wax ing or
icing, such as the customer is using an incorrect
fuel type in winter season or water mix ed with the
fuel.
If a problem is found, repair as necessary.
Was a problem found?—Verify repair Go to Step 28
28 Replace the fuel filter.
Was the problem solved?—Verify repair Go to Step 29 Step Action Value(s) Yes No

Vacuum Pump Small Window

6E–402 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
POOR FUEL ECONOMY SYMPTOM
DEFINITIONS: Fuel economy, as measured by an actual road test, is noticeably lower than expected. Also, economy
is noticeably lower than it was on this vehicle at one time, as previously shown by an actual road test. (Larger than
standard tires will cause odometer readings to be incorrect, and that may cause fuel economy to appear poor when it
is actually normal.)
Step Action Value(s) Yes No
1Was the “On-Board Diagnostic (OBD) System Check”
performed?
—Go to Step 2Go to On Board
Diagnostic
(OBD) System
Check
2 1. Perform a bulletin search.
2. If a bulletin that addresses the symptom is found,
correct the condition as instructed in the bulletin.
Was a bulletin found that addresses the symptom?—Verify repair Go to Step 3
3 Was a visually/physical check performed?
—Go to Step 4Go to Visual /
physical Check
4 Check owner's driving habits.
Is the A/C “On” full time?
Are tires at the correct pressure?
Are ex cessively heavy loads being carried?
Is acceleration too much, too often?—Go to Step 5Go to Step 6
5 Review the items in Step 4 with the customer and
advise as necessary.
Is the action complete?—System OK—
6 Check for low engine coolant level.
Was a problem found? —Verify repair Go to Step 7
7 Check for incorrect or faulty engine thermostat. Refer
to Engine Cooling.
Was a problem found?—Verify repair Go to Step 8
8 Check for proper calibration of the speedometer.
Does the speed indicated on the speed meter closely
match the vehicle speed displayed on the Tech 2?—Go to Step 10Go to Step 9
9 Diagnose and repair the inaccurate speedometer
condition as necessary. Refer to Vehicle Speed
Sensor in Electrical Diagnosis.—Veri fy repai r—
10 Check for proper calibration of the fuel gauge.
Was a problem found? —Verify repair Go to Step 11
11 Check the torque converter clutch (TCC) for proper
operation (if A/T model). If a problem is found, repair
as necessary.
Was a problem found?—Verify repair Go to Step 12
12 1. Using the Tech 2, ignition “On” and engine “Off”.
2. Monitor the “Neutral Switch” in the data display.
Does the Tech 2 indicate correct “Neutral Switch”
status depending on any shift positions?
If a problem is found, repair as necessary.
Was the problem found?—Verify repair Go to Step 13

6E–410 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
25 Remove the eye bolt with gauze filter from the
injection pump and check for the following conditions.
Objects blocking at the gauze filter. Check for a
condition that causes contaminated fuel, such as
the customer is using an aftermarket fuel filter or
ex tended maintenance interval.
Check for a condition that causes fuel wax ing or
icing, such as the customer is using an incorrect
fuel type in winter season or water mix ed with the
fuel.
If a problem is found, repair as necessary.
Was the problem found?
—Replace the
eye bolt with
gauze filter and
verify repair Go to Step 26
26 Remove the injection nozzles from the engine and
check for the following conditions.
Improper splay condition.
Operating pressure is incorrect.
If a problem is found, repair as necessary.
Was the problem found?
—Replace the
injection nozzle
and verify repair Go to Step 27 Step Action Value(s) Yes No
1st Stage 2nd Sta ge
4JA1-TCApproximatly
19.0 MpaApprox ima tly
33.5 Mpa
4JH1-TCApproximatly
19.5 MpaApprox ima tly
33.8 Mpa