Remove injectors but leave hoses connected. Place injectors in individual measuring containers. Operate fuel pump to build up pressure, then turn pump off.
Lift air flow sensor plate half-way to operate injectors until one container has filled to 3.4 oz. (100 cc). Volume of fuel in other containers should not vary more than 10-20%. Spray pattern must be even and cone-shaped.
If one injector does not conform to specifications, swap hoses from it and one good injector at fuel distributor and retest. If same container is low, injector is faulty or fuel line is restricted. If other container is low, fuel distributor must be replaced.
Relieve system pressure and remove pressure testing gauge. Turn on pump to build up pressure. Injectors may leak slightly, but should stop leaking within 15 seconds. If drops form, check air flow sensor plate height, sticking fuel distributor plunger, or injector opening pressure.
Remove injectors from vehicle and use injector tester to determine opening pressure. See Fig 1 . Check readings against specifications. See Fuel Injection Pressure Testing table. Replace injectors if faulty.

Fig 1: Fuel Injector Tester If opening pressure of injectors is not within limits, replace injectors.

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.

• Brakes feel soft, pull hard to one side, or make grinding noises.

• The engine overheats, stalls repeatedly, or misfires under load.

• You are missing required tools, torque specs, or safe lifting equipment.

• You are not confident in the next step or safety outcome.

Safety Warning

Fuel Injectors