Isuzu KB P190. Manual - part 802

Fuel System – V6 

Page 6C – 6 

 

Fuel Pump 

Single Turbine Fuel Pump 

The fuel pump is an integral part of the Fuel Pump and Sender Assembly, refer to Figure 6C –  3. 

Figure  6C–  2 details the fuel flow through the single turbine fuel pump. 

 

Figure  6C–  2 

Legend 

 Fuel 

 Vapour 

out 

1 Inlet 

Body 

2 Impeller 

Housing 

3 Impeller 

4 

Fuel Pump Housing 

Fuel System – V6 

Page 6C – 7 

 

Fuel Flow 

Fuel (A) is drawn into the modular fuel pump and sender 
assembly reservoir from the fuel tank, through the primary 
umbrella valve (5) and into the fuel pump impeller, via the 
internal strainer (4) at the fuel pump (1) inlet. At the impeller, 
vapour (C) is separated from the fuel. The vapour is ejected 
from the fuel pump into the reservoir via a port next to the 
fuel pump inlet. 

High-pressure fuel then flows through the end cap, the lower 
connector and the flexible line. From the flexible line, fuel 
exits the modular fuel pump and sender assembly through 
the fuel feed port and flows on to the externally-mounted 
fuel filter and the engine. 

A fuel pressure regulator is located in the modular fuel pump 
and sender assembly; fuel not used by the engine (B) is 
returned to the modular fuel pump and sender assembly via 
the fuel return line and the fuel return port in the modular 
fuel pump and sender assembly cover. The return fuel 
enters the jet pump standpipe (3) of the reservoir via the 
return fuel tube. 

Vehicle fuel line pressure is maintained by a pressure 
regulator (2) located within the modular fuel pump and 
sender assembly. 

When the engine is switched off, the reservoir remains full of 
fuel, due to the action of the primary umbrella valve. At high 
fuel levels, fuel tank overflow enters the reservoir over the 
top of the reservoir. Fuel level in the reservoir is also 
maintained by returned engine fuel. 

Electrical power is supplied to the fuel pump by a connector 
secured to the modular fuel pump and sender assembly 
cover. An internal harness (not shown) assembly completes 
the connection to the pump. 

Figure 6C –  3 

 

Fuel System – V6 

Page 6C – 8 

 

3 System 

Checks 

3.1 

Fuel Pump Flow Test 

If a reduction of the fuel supply is suspected, perform the following checks. 

1 

Ensure there is sufficient fuel in the tank. 

2 

With the engine running, check the fuel lines from the 
fuel tank to the injectors for evidence of leakage. 
Retighten, if the lines or the connections are loose. 
Also, check the fuel lines for restrictions such as 
squashed or clogged fuel line. 

3 

Depressurize the fuel system, refer to 3.4 

Fuel 

System Depressurisation. 

4 

Disconnect the fuel line at the fuel rail. 

5 

Connect a hose from the fuel line and place the open 
end into a clean container. 

6 

Connect the fuel pump relay terminals (2) with a 
jumper wire (1) as shown, then turn the ignition to the 
ON position to operate the fuel pump, then check the 
fuel pump flow rate. 

 

Do not generate any sparks when connecting 
the jumper wire. 

Fuel delivery test time ....................................... 15.0 Sec 

Fuel delivery rate .....................................0.38 Litres Min 

N O T E  

If the fuel flow rate is below the minimum value, 
conduct a fuel pressure test, refer to 3.2
 

Fuel Pressure Test. 

Figure 6C –  4 

 

3.2 

Fuel Pressure Test 

 

To reduce the risk of fire or personal injury, 
depressurise the fuel system before servicing 
any fuel system components, refer to 3.4
 Fuel System Depressurisation. 

Gauge Installation 

1 

Turn the ignition switch off. 

2 

Depressurise the fuel system, refer to 3.4 

Fuel System Depressurisation. 

Fuel System – V6 

Page 6C – 9 

 

 

A small amount of fuel may be released when 
connecting the fuel pressure gauge to the fuel 
pressure test point. Cover the fittings with a 
shop towel to absorb any fuel spillage before 
connecting the fuel pressure gauge. After the 
fuel pressure test procedure, place the soiled 
towel in an approved container for disposal. 

3 

At the fuel pressure test point, remove the Schrader valve sealing cap. 

4 

Connect the fuel pressure gauge (1) (tool 
No. J 34730–1A) to the fuel gauge Schrader fitting 
adapter (2) (tool No. AU453), then install to the fuel 
pressure test port (3). Wrap a shop towel around the 
fitting while connecting the fuel pressure gauge to 
avoid and/or capture any fuel spillage. 

5 

Route the bleed hose of the fuel gauge into an 
approved fuel container. 

 

 

Figure 6C –  5 

 

After connecting the fuel pressure gauge and 
pressurising the fuel system, inspect for fuel 
leaks at the fuel pressure gauge and the fuel 
pressure test point. 

6 Either: 

Using Tech 2, enable the fuel pump to pressurise the fuel system, refer to 0C Tech 2. Inspect for fuel leaks at the 
fuel pressure gauge and fuel pressure test point, then bleed the air from the fuel pressure gauge. 

 or: 

Reinstall the fuel pump relay and fuel pump fuse, then open the fuel gauge bleed valve (4) to bleed the air from the 
fuel pressure gauge, refer to Figure 6C –  5. 

7 

Remove and place the soiled shop towel in an approved container. 

Test 

1 

Start the engine and record the fuel pressure. 

2 

Turn the ignition switch off. 

3 

If required, perform any tests and/or diagnostic procedures: 

• 

For the fuel system leak test, refer to 3.3  Fuel Leak Test. 

• 

For the fuel injector leak-down test (for vehicles fitted with a V6 engine, refer to 6C1-3 Engine Management  – 
V6 – Service Operations. 

4 

Depressurise the fuel system, refer to 3.4 

Fuel System Depressurisation. 

Removal 

1 

Turn the ignition switch off. 

2 

Depressurise the fuel system, refer to 3.4 

Fuel System Depressurisation.