Contents: Preliminary checks ↧ Only for engines with PFI system ↧ Only for engines with TBI system ↧
Note: The following check is performed under the condition that the fuel pump is operating and the correct fuel pressure is maintained (see section 3).
Preliminary checks
1. Check all electrical connections associated with the system. Poor electrical connections and a broken ground wire can cause a lot of trouble, leading to more serious problems.
2. Make sure the battery is fully charged as accurate voltage is required to correctly determine the amount of fuel.
3. Check the air filter element: a dirty or partially clogged filter will greatly reduce performance and economy (see chapter 1).
4. If a blown fuse is found, replace it and check to see if it blows again. If this happens, look for a short in the wiring harness going to the fuel pump.
Only for engines with PFI system
5. Check the air intake from the air flow sensor (MAF) (if available) to the intake manifold for leaks that will cause a lean mixture. Also check the condition of the vacuum hoses connected to the intake manifold.
6. Disconnect the air intake and check for dirt, soot or other residual deposits on the walls of the throttle body and especially around it. If there is dirt, clean the throttle body with carburetor cleaner.
7. After starting the engine, place the screwdriver on each injector in turn and listen through the handle for a click, indicating correct operation.
8. With the engine off and the electrical connector disconnected from the injector, measure the resistance of each injector (see illustration). Each injector should have a resistance of approximately 14.7 ohms. If it does not, the injector is faulty.
11.8 Measure the resistance of each injector using a digital ohmmeter
9. Other system checks should be performed by a General Motors service department or a qualified service center, as damage to the control unit may occur (if it doesn't work properly).
Only for engines with TBI system
10. Set the vehicle's parking brake, remove the air filter cover and, with the engine idling and the gearshift lever in the Park position, observe the operation of the injectors. The sprayed fuel should form a smooth cone that reaches the throttle opening.
- a) If the spray cone is loose or uneven, the nozzle is either clogged or faulty. Sometimes gasoline additives designed specifically to clean injectors can help. If they don't help, car service centers have more efficient cleaning equipment.
- b) If the injector does not work at all, check the electrical connector. If the contact is good and voltage is supplied to the injector, but the injector still does not work, then it is faulty.
[The text of the article was obtained from the website ChevyMan.ru]