Suzuki GW250 Service Manual page 178

Step 4
IAP sensor check 1
1) Turn the ignition switch OFF.
2) Connect the ECM couplers and IAP sensor coupler.
3) Insert the needle-point probes to the lead wire coupler.
4) Run the engine at idle speed and measure the IAP sensor
output voltage between the Bl/W wire (#1) or W/R wire (#2)
and B/Br wire.
 09900-25008: Multi circuit tester set
09900-25009: Needle-point probe set
 Tester knob indication: Voltage ()
 IAP sensor output voltage:
Approx. 2.6 V at idle speed (atmospheric pressure:
approx. 100 kPa (760 mmHg)
#1: (+ terminal: Bl/W – - terminal: B/Br)
#2: (+ terminal: W/R – - terminal: B/Br)
Is check result OK?
YES Go to Step 5.
• Check the vacuum hoses for crack or damage.
NO • If vacuum hoses are OK, replace the IAP sen-
sor with a new one. (4-91)
Step 5
IAP sensor check 2
1) Turn the ignition switch OFF.
2) Remove the IAP sensor. (4-91)
3) Connect the vacuum pump gauge to the vacuum port of the
IAP sensor.
4) Arrange 3 new 1.5 V batteries 1 in series (check that total
voltage is 4.5 – 5.0 V) and connect - terminal to the ground
terminal B and + terminal to the VCC terminal A.
5) Check the voltage between Vout terminal C and ground.
Also, check if voltage reduces when vacuum is applied using
the vacuum pump gauge.
 09917-47011: Vacuum pump gauge set
09900-25008: Multi circuit tester set
 Tester knob indication: Voltage ()
ALTITUDE (Reference)
m ft
0 – 610 0 – 2 000
611 – 1 524 2 001 – 5 000
1 525 – 2 438 5 001 – 8 000
2 439 – 3 048 8 001 – 10 000
Is check result OK?
Replace the ECM with a known good one, and
YES
inspect it again.
NO Replace the IAP sensor with a new one.
ATOMOSPHERIC OUTPUT
PRESSURE VOLTAGE
kPa mmHg
100 – 94 760 – 707 3.1 – 3.6
94 – 85 707 – 634 2.8 – 3.4
85 – 76 634 – 567 2.6 – 3.1
76 – 70 567 – 526 2.4 – 2.9
4
5
V
FI SYSTEM DIAGNOSIS 4-37
V