Usage:
3508, 3512 and 3516 Low Speed Marine Engines With The Lower Power Ratings
A new fuel injector is available for 3508 Marine Engines 69Z1-69Z275, 3512 Marine Engines 66Z1-66Z190, and 3516 Marine Engines 72Z1-72Z339. The new injector reduces black smoke at low rpm's and loads. The new injectors reduce smoke because they have only one scroll instead of two, and thus fuel timing is not changed when engine load is reduced.
The new injectors can be installed in all the earlier marine engines, but only in complete sets. Do not use them with either of the former injectors (see chart) because the fuel injection rate is higher with the new injectors.
If a set of new injectors is installed, change the fuel setting and high idle to maintain the same power and performance. Use the following procedure:
1. Record the fuel setting stamped on the engine information plate on the camshaft inspection side cover.
2. Subtract 0.6 mm from the fuel setting and multiply by 0.76. The result is the new fuel setting.
Example: The fuel setting stamped on information plate is 10.0 mm. 10.0 minus 0.6 equals 9.4. 9.4 times 0.76 equals 7.1 mm, which is the new fuel setting.
3. Record the high idle setting on the engine information plate.
4. The high idle rpm should be reduced 6.6 rpm for each 1 mm that the fuel setting is reduced.
Example: Present fuel setting 10.00 mm Minus new fuel setting 7.10 mm The change in setting is 2.90 mm
2.9 mm times 6.6 equals 19 rpm, the reduction in high idle to be made.
If the present high idle stamped on the plate is 1330 rpm, then subtract 19 rpm, giving a new high idle of 1311 rpm.
NOTE: The preceding high idle change example is based on the factory governor droop adjustment which is usually about 13%. If the droop adjustment is not about 13%, then a different method of computing the high idle is required. If the droop is not 13%, go to Step 5. (The droop can be computed by comparing the full load rpm to the high idle rpm.)
5. Assume the droop is only 5% and the high idle is 1260 rpm, and the fuel settings are:
Present 10.00 mm New 7.10 mm Change in setting 2.90 mm
Change for a standard 13% droop would be 2.9 mm times 6.6 rpm/mm changed, which equals 19 rpm. But, the change for only 5% droop is: 5/13 times 19 rpm equals 7 rpm change. Subtract 7 from 1260 gives you the new high idle of 1253 rpm.
6. Stamp both new settings on the information plate and cross out the former settings.
7. Update your Product Information System (or the Worldwide Information System) for this engine.