Mariner 150 HP, 150 Magnum II, 150 Magnum III, 150 Magnum EFI
Mariner 175 HP, 175 Magnum EFI
Mariner 200 HP, 200 Magnum EFI, 250 HP, 275 HP
Book Excerpt: 1990-1993 Mariner Outboard 2.5-275 HP Repair Manual
FUEL MANAGEMENT TESTS
FUEL RAIL PRESSURE TEST
The following test can be performed to determine if fuel under sufficient pressure is available to the injectors. The test can help isolate a malfunction as either a fuel delivery problem or an electrical system failure.
It is normal for fuel pressure to vary between approximately 34-39 psi (214-269 kPa) when checking fuel pressure while the engine is running.
Remove the plastic cap from the fuel rail service port located on the lower port side of the induction manifold.
Connect fuel pressure gauge assembly (part No. 91-16850, or equivalent) to the service port as shown in Figure 101.
Note that Figure 101 shows the induction manifold with the cover removed. It is not necessary to remove the cover to perform this test.
Place the ignition switch in the ON position (engine not running) and allow the electric fuel pump to operate for approximately 10 seconds. Note the pressure gauge reading.
NOTE: When the ignition switch is turned to ON (engine not running), the electric fuel pump will operate for approximately 30 seconds. If the ignition switch is turned OFF for 30 seconds, then back ON, the pump will run for another 30 seconds.
Basic repair of Mariner outboard power heads is similar from model to model, with minor differences. Some procedures require the use of special tools, which can be purchased from a Mariner outboard dealer.
Certain tools may be fabricated by a local machinist, often at substaintial savings. Power head stands are available from specialty shops and marine product distributors.
Make sure the engine stand is of sufficient capacity to support the size of the engine.
Work on the power head requires considerable mechanical ability. Carefully consider your capabilities before attempting any operation involving major disassembly of the engine.
Much of the labor charge for dealer repairs involves the removal and disassembly of other parts to reach the defective component.
Even if you decide not to tackle the entire power head overhaul after studying the test and illustrations in this chapter, it can be financially beneficial to perform the preliminary operations yourself and then take the power head to your dealer.
Since many marine dealers have lengthy waiting lists for service (especially during the spring and summer seasons), this practice can reduce the time your unit is in the shop. If you have done much of the preliminary work, your repairs can be scheduled and performed much quicker.