Fuel System - Fuel Pressure Diagnosis
Article No. 85-13-4FUEL PRESSURE - DIAGNOSIS
FORD 1984-85 LTD, THUNDERBIRD, MUSTANG
LINCOLN-MERCURY 1984-85 MARQUIS, COUGAR, CAPRI
CALIBRATIONS: All with 3.8L EEC IV
WARNING: This modification is authorized only for the listed engines. Performing this modification on other engine calibrations is unauthorized and could create liability under applicable federal or local laws.
Figure 2:
Low fuel pressure can be an intermittent condition. When low fuel pressure is the cause of an elusive drive concern, it can be identified by observing fuel pressure when the concern occurs. To do this, improvise the lines necessary to install a pressure gauge so it is outside the vehicle and can be observed while the vehicle is driven. If fuel pressure drops when drive concern occurs, check the electric connections at fuel pump, fuel pump relay and circuit No. 87 (pin connector No. 22 at the processor). Check all wire harness connectors in the fuel pump circuits. Refer to Figure 2.
If the connections are good, check the fuel pump volume and pressure as outlined in Section 24-35, Volume D of the 1985 Shop Manual.
When a fuel pump relay is replaced and the system then has fuel pressure but will still not start/run the processor may have been damaged by the defective pump relay.
OTHER APPLICABLE ARTICLES: None
WARRANTY STATUS: "INFORMATION ONLY"