FUEL SYSTEM
5 E 73662
BSO / SAV EMISSION FUEL SYSTEM
Index
Table of Contents Page Identification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5E-1 Replacement Parts Warning . . . . . . . . . . . . . . . 5E-1 Torque Specifications . . . . . . . . . . . . . . . . . . . . . 5E-1 Special Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5E-1 Carburetor Specifications . . . . . . . . . . . . . . . . . . 5E-2 Carburetor Adjustment Specifications . . . . . . . 5E-2 Engine Specifications . . . . . . . . . . . . . . . . . . . . . 5E-2 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5E-3 Special Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5E-3 Carburetor Top Cover . . . . . . . . . . . . . . . . . . 5E-3 Sealed Idle Mixture Screws . . . . . . . . . . . . . 5E-3 Metering Assembly . . . . . . . . . . . . . . . . . . . . 5E-4 Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5E-5 Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5E-6 Flame Arrestor . . . . . . . . . . . . . . . . . . . . . . . . 5E-6 Fuel Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5E-6 Positive Crankcase Ventilation (PCV) . . . . 5E-6 Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . 5E-7 Checking Ported Vacuum Switch and Carburetor Vacuum Circuit for Correct Operation . . . . . . . . . . . . . . . . . . . . . 5E-7 Service Procedures . . . . . . . . . . . . . . . . . . . . . . . 5E-8 Checking Positive Crankcase Ventilation (PCV) Valve . . . . . . . . . . . . . . . . . 5E-8 Removing Seals From Idle Mixture Screws . . . . . . . . . . . . . . . . . . . . 5E-9 Installing New Seals . . . . . . . . . . . . . . . . . . . 5E-9 Carburetor Installation . . . . . . . . . . . . . . . . . 5E-10 Ported Vacuum Switch Installation . . . . . . 5E-10 Emissions System Connections . . . . . . . . 5E-11 Propane Assisted Idle Set Procedure . . . . 5E-12 Test Equipment . . . . . . . . . . . . . . . . . . . . . . . . . 5E-14 Emissions Testing . . . . . . . . . . . . . . . . . . . . . . . 5E-14
Index 5E-0 – BODENSEE EMISSION FUEL SYSTEM
90-823226--1 996
Identification
Torque Specifications
The Bodensee Emissions version of the Weber WFB carburetor has vacuum fittings on the front side.
Description
lb. in.
Carburetor to Manifold
132
Fuel Line to Carburetor
lb. ft.
N·m 15
18
24
Special Tools Mercury Marine Special Tools Description
a 73701
b
Part Number
Universal Carburetor Gauge
91-36392
Tachometer
91-59339
Other Special Tools Description
Part Number
Universal Carburetor Stand a - Vacuum Fittings
TORX Screwdrivers (15,20&25)
Replacement Parts Warning ! WARNING Electrical, ignition and fuel system components on your MerCruiser are designed and manufactured to comply with U.S. Coast Guard Rules and Regulations to minimize risks of fire and explosion. Use of replacement electrical, ignition or fuel system components, which do not comply with these rules and regulations, could result in a fire or explosion hazard and should be avoided.
Ob i Locally Obtain L ll
Propane Bottle [14 oz. (400 grams)] Propane Enrichment Kit (Various Suppliers) Ported Vacuum Switch (PVS) Socket Wrench (Various Suppliers)
(1) J26911 (2) YA7148 (3) 7148 (1) No PN (2) S9842A (3) 7267
Special Tool Suppliers: (1) Kent-Moore Part Number (2) Snap-On Part Number (3) OTC Part Number
NOTE: Weber carburetors will have a “star” shaped socket in the head of some screws. A TORX screwdriver must be used on this type of screw. The sizes used are numbers 15, 20 and 25.
Index 90-823226--1 996
BODENSEE EMISSIONS FUEL SYSTEM - 5E-1
Carburetor Specifications Units of Measurements In.(mm)
Engine Model
MCM 4.3LX
Carb Type
Primary Mercury Number Jet (Manufacturer Number) Size
Weber WFB
3310-806120 (9662)
Secondary Jet Size
Metering Rod Number
Metering Rod Spring Color
.080
16-656457
Natural
.086
Carburetor Adjustment Specifications Make And Model
Weber WFB
Float Level
1-9/32 (33)
Float Drop
2 In. (51)
Pump Rod Hole Location
Number 3 from end (Hole closest to lever pivot point)
Accelerator Pump
7/16 (11) (Note 1)
Choke Pull Off
1/8 (3.5)
Choke Coil Rod
Top of Rod Even with Bottom of Lever Hole (Note 2)
Note: 1. Measured from top of Carburetor to bottom of “S”- Link Note: 2. Remove choke rod from lever hole. choke held closed and choke rod is pushed down with top edge of rod even with bottom edge of hole.
Engine Specifications Model
4.3LX Alpha
Thermostat
160°F (71°C)
Ignition Timing
10° BTDC
Idle Speed in Neutral
775 RPM
Propane Idle Speed (See Procedure)
850 RPM
Index 5E-2 – BODENSEE EMISSION FUEL SYSTEM
90-823226--1 996
Description
Special Notes
The Bodensee Emissions system is designed to lower exhaust emissions to meet regulations on the “Bodensee”. It consists of the following items: a Positive Crankcase Ventilation (PCV) circuit, a Ported Vacuum Switch (PVS) circuit, a higher temperature thermostat [160°F (71°C)], and a specially designed Weber WFB carburetor.
IMPORTANT: Disassembly and repair of the Bodensee Emissions carburetor is basically the same as the other Weber WFB carburetors. There are some internal and external differences that are noted following:
Weber WFB carburetor is unique in design, as the main body and flange are cast as a one piece unit. This, along with the bowl cover, make up the two piece construction which is made of light, durable aluminum to dissipate heat.
Carburetor Top Cover The carburetor top cover (air-horn) has vacuum fittings for connection to the “Ported Vacuum Switch” (PVS).
There are two separate float circuits. Each float circuit supplies fuel to a primary low speed circuit and a primary and secondary high speed circuit. The bowls are vented to the inside of the air horn. A connecting vent passage effects a balance of the air pressure between the two bowls. The float needle valves are installed at an angle to provide the best possible seating action on the needles. This provides better needle response to float movement, also. The PVS circuit is used in conjunction with the idle circuit. When the engine is cold, the PVS circuit is closed. This shuts off a metered air-bleed to the idle circuit, to maintain a rich idle circuit for warm-up. Once the engine warms up [ approximately 128°F (54°C)], the PVS opens, allowing a metered amount of air to be mixed into the idle circuit. This leans the idle circuit to the proper operating air-fuel ratio. The high speed circuits use staged step-up rods in the main metering jets to control the amount of fuel admitted to the nozzles. The position of the step-up rod is controlled by manifold vacuum applied to the vacuum piston.
a 73701
a - Vacuum Fittings
Sealed Idle Mixture Screws The idle mixture screws have seals that prevent tampering with the idle mixture after the mixture has been properly adjusted.
A primary air bleed located in the venturi cluster prevents a rich condition or bog as the high speed circuit is reactivated after deceleration. Small “L” shaped metal tabs, called “distribution tab(s),” are attached to some venturi clusters and protrude into the air stream at the proper location to aid distribution of fuel on selected applications. The PCV circuit ventilates crankcase vapors (unburned gases) back into the intake manifold to be burned again.
a
71798
a - Screw Seals
Index 90-823226--1 996
BODENSEE EMISSIONS FUEL SYSTEM - 5E-3
METERING JETS
Metering Assembly The metering rod assemblies are different in the following ways:
The metering jets in this carburetor are taller than the jets in a standard carburetor. Emissions
Emissions
b
Standard
a
d
c a
b
73728
a - Jets For 3 Step Metering Rod b - Jets For 2 Step Metering Rod
e 73732
METERING ROD HAS “THREE STEPS” -VS- TWO
Emissions
73726
b
Standard
a Standard
d
73724
c PISTON SHAPE IS DIFFERENT AND HAS A SECOND SPRING
e 73729
a b c d e
-
Emissions
Piston Metering Rod Spring Jet Piston Cover
73730
Standard
73727
Index 5E-4 – BODENSEE EMISSION FUEL SYSTEM
90-823226--1 996
PISTON ASSEMBLY COVER IS HIGHER
Precautions ! WARNING Always disconnect battery cables from battery BEFORE working on fuel system to prevent fire or explosion.
! WARNING 73735
Emissions
Standard 73725
73736
PISTON BORE HAS A STEP ON EMISSIONS MODEL
Be careful when cleaning flame arrestor and crankcase ventilation hose: gasoline is extremely flammable and highly explosive under certain conditions. Be sure that ignition key is OFF. DO NOT smoke or allow sources of spark or open flame in area when cleaning flame arrestor and crankcase ventilation hose.
! WARNING Be careful when changing fuel system components: gasoline is extremely flammable and highly explosive under certain conditions. Be sure that ignition key is OFF. DO NOT smoke or allow sources of spark or open flame in area while changing fuel filter. Wipe up any spilled fuel immediately.
! WARNING Make sure no fuel leaks exist, before closing engine hatch.
! CAUTION DO NOT operate engine without cooling water being supplied to water pickup holes in gear housing or water pickup inlet, or water pump impeller will be damaged and subsequent overheating damage to engine may result.
73737
Index 90-823226--1 996
BODENSEE EMISSIONS FUEL SYSTEM - 5E-5
Maintenance
Fuel Filter
Flame Arrestor
Maintenance for fuel inlet filters is the same as standard engine (See the Weber WFB carburetor section of the appropriate MerCruiser Service Manual).
Maintenance for the flame arrestor is the same as standard engine (See the Weber WFB carburetor section of the appropriate MerCruiser Service Manual). The only difference in the flame arrestor on an engine with the Bodensee Emissions system is in the vent hose bracket. This bracket has a fitting on one side only.
Positive Crankcase Ventilation (PCV) The Positive Crankcase Ventilation (PCV) valve should be replaced once a year.
a b b
d
a 71798 71925
c a - PCV Valve b - Hose
71797
a b c d
-
Stud Vent Hose Bracket Vent Hose To Starboard Valve Cover NO VENT HOSE ON THIS SIDE
Index 5E-6 – BODENSEE EMISSION FUEL SYSTEM
90-823226--1 996
2. Plug the hose with your finger. You should not feel vacuum on the hose at this time.
Troubleshooting NOTE: Review the “Description” section of this manual for an understanding of system operation, before troubleshooting the carburetor. Do not assume that a problem exists inside the carburetor without first eliminating other engine system components as potential problem areas. Be sure to check the following items: • Engine operating temperature (Proper Thermostat - See “Engine Specification Chart”). • Correct ignition timing (See “Engine Specification Chart”). • Cylinder compression.
73734
• Ported Vacuum Switch (PVS) functioning properly. Use the following procedure to check for a faulty Ported Vacuum Switch (PVS):
Checking Ported Vacuum Switch and Carburetor Vacuum Circuit for Correct Operation
3. Allow engine to run and warm up to normal operating temperature. Disconnect the hose again and check for vacuum. If PVS is functioning properly, there should be vacuum present at this time. If vacuum is not present, check to ensure that hoses are properly connected and are not cracked or plugged. Then, proceed to check the carburetor vacuum circuit. 4. Reconnect rear hose to carburetor.
NOTE: The engine must be cold before performing the first 4 steps. 1. Start engine. Disconnect the hose from the carburetor at the location shown.
NOTE: The engine must be warm before performing the next step. 5. Start engine and allow it to reach normal operating temperature. 6. Disconnect the two hoses on the front of carburetor.
73738
73733
Index 90-823226--1 996
BODENSEE EMISSIONS FUEL SYSTEM - 5E-7
IMPORTANT: Ensure that engine is running at 775 RPM or below. This ensures that the carburetor is not running on the “Off-Idle” circuit. 7. Connect a tachometer to the engine. 8. Plug the vacuum ports on the front of the carburetor. Be sure to only plug one port at a time. When vacuum port is covered, the engine RPM should increase. Repeat test on the other port. If vacuum is not present, a vacuum port may be plugged. Clean vacuum ports and repeat the entire test.
Service Procedures Checking Positive Crankcase Ventilation (PCV) Valve 1. Start engine and allow it to reach normal operating temperature. 2. Remove PCV valve from valve cover. Plug the opening with your finger. A vacuum should be felt. 3. Stop the engine. 4. Shake the valve to ensure that the internal components are free to move.
73740
73743
73739
9. When test is complete and PVS is determined to be functioning properly, reconnect all hoses in vacuum circuit.
Index 5E-8 – BODENSEE EMISSION FUEL SYSTEM
90-823226--1 996
2. Align the opening in the plug with the tab on the cup and push down until it snaps in place.
Removing Seals From Idle Mixture Screws ! WARNING Avoid fire or explosion. Using a cutting wheel to cut the seals will cause sparks, which will ignite any fuel that is present. Ensure that there is no fuel present and that carburetor is removed from engine prior to cutting the seals from the carburetor idle mixture screws. 1. Remove carburetor from the engine.
a
2. Drain all fuel from the carburetor. 3. Using a cutting wheel, make a cut on both sides of the seal casing. Using a suitable device, pry the plug from the inside of the seal. Once the plug is removed, the idle mixture screw can be removed and the seal casing can be removed.
b 73789
a - Opening In Plug b - Tab On Cup
73744
Installing New Seals 1. Install new seal cup, spring and idle mixture screw. IMPORTANT: Do not install the seal plug until the “Propane Assisted Idle Mixture Adjustment” procedure has been completed.
Index 90-823226--1 996
BODENSEE EMISSIONS FUEL SYSTEM - 5E-9
Carburetor Installation
Ported Vacuum Switch Installation
3. Install new carburetor as follows:
! CAUTION
a. Place new gasket on adapter plate. b. Install carburetor and throttle bracket and secure with new attaching hardware. Torque fasteners to 132 lb.in. (15 N⋅m).
Be careful not to break off fittings when installing the ported vacuum switch (PVS) in the following step.
c. Connect fuel line. To prevent over-tightening, hold fuel inlet nut with a suitable wrench and tighten fuel line connector securely.
NOTE: A special tool is available to install the PVS. Refer to the “Tool Chart” at the beginning of this manual. 1. If removed, install ported vacuum switch (PVS) into reducer bushing. Apply Loctite Pipe Sealant with Teflon to threads before installing. Tighten it securely and position the fittings toward back of engine as shown.
d c
b b 71173
a 71913
a - Reducer Bushing b - Ported Vacuum Switch (PVS)
b
a 71172
a b c d
-
Throttle Bracket Attaching Hardware Fuel Line Fuel Inlet Nut
Index 5E-10 – BODENSEE EMISSION FUEL SYSTEM
90-823226--1 996
Emissions System Connections 1. Install the positive crankcase ventilation (PCV) valve in the port valve cover.
3. Connect hoses to ported vacuum switch (PVS) as shown.
2. Connect hose to PCV valve. Connect opposite end of hose to fitting on front of carburetor.
b
b
c a
d
71924
a
71925
c
d b
a a b c d
-
Ported Vacuum Switch Hoses (Switch To Y-Fitting) Hoses (To Front Side Of Carburetor) Hose (Y-Fitting To Back Side Of Carburetor)
73702
c 73701
a - PCV Valve b - Hose c - Carburetor Fitting (Connect Hose Here)
Index 90-823226--1 996
BODENSEE EMISSIONS FUEL SYSTEM - 5E-11
IMPORTANT: The hose that runs from the T-Fitting to the back side of the carburetor must be routed beneath the throttle linkage as shown in the following illustration. Use care to ensure that the hose does not rub against linkage.
b
a
71916
Propane Assisted Idle Set Procedure ! WARNING Avoid fire or explosion. Observe the following precautions when performing this procedure. • Do not operate the engine without the flame arrestor installed, above the speeds listed in this procedure. • Propane is extremely flammable and explosive. Ensure that the following test is performed in a well ventilated area with the engine hatch open. • Ensure that there is no spark or open flame in the test area. • Do not start the flow of propane until the hose has been placed into the carburetor and the engine has been started. • Keep a fire extinguisher available when performing this test.
NOTE: This test must be performed any time the carburetor has been disassembled and internal components have been disturbed or the idle mixture screws have been tampered with. The test should also be performed if other component parts of the emissions system have been altered, repaired, or replaced. IMPORTANT: Ensure that the PVS is functioning properly before performing this procedure. 1. As a starting point, set both idle mixture screws at 1 turn out from the fully seated position.
71917
2. Start engine and allow it to warm up to normal operating temperature. If engine has been run above idle speed, allow engine to idle for 3 to 5 minutes to stabilize the engine. 3. Remove flame arrestor.
a - T-Fitting b - Hose - T-Fitting T Back Of Carburetor
Index 5E-12 – BODENSEE EMISSION FUEL SYSTEM
90-823226--1 996
4. Insert special “Y”-Adapter hoses into carburetor as shown. Place the hoses behind the choke plate to help hold them in place.
8. Release the propane flow valve and allow engine speed to stabilize. Slowly adjust the mixture screws by equal amounts, pausing between adjustments to allow engine speed to stabilize, to achieve 775 RPM.
73731
5. Connect the hose from the propane bottle valve to the “Y”-Fitting. 6. With engine idling at normal operating temperature, press the propane flow button on the valve. Slowly begin opening the propane metering valve until maximum engine RPM is reached. When too much propane is added, engine RPM will decrease. “Fine tune” the metering valve to obtain the highest RPM.
73722
9. Press the propane flow valve. Engine RPM should increase to 850 RPM. If it does not, repeat steps 5 thru 7.
a
b
73662 73673
a - Propane Flow Valve b - Propane Metering Valve
7. With propane still flowing, adjust the idle speed screw (not the mixture screws) to obtain 850 RPM. Again, “fine tune” the propane metering valve to obtain the highest engine RPM. If there has been a change in the maximum RPM, readjust the idle speed screw to 850 RPM.
10. If after performing the above procedure several times, the correct results can still not be obtained, check the following: • PVS not working properly. • Incorrect float level. • Vacuum leaks.
Index 90-823226--1 996
BODENSEE EMISSIONS FUEL SYSTEM - 5E-13
11. Once the idle speed and mixture adjustment is correct, install the seal plugs over mixture screws. Ensure the opening in plug snaps into the tab in the cup.
c b
73789
Emissions Testing NOTE: This test will be performed by an authorized agency for the area that the boat will be operated. This agency will be equipped with the appropriate test equipment and adapters for this engine. The only item that must be supplied by the boat owner/operator are the exhaust test probes. These test probes should be carried aboard the vessel at all times. The following steps will explain how these probes are to be installed.
a b
a
71926
71798
a - Exhaust Test Probes (2) b - Exhaust Elbow Adapter Fittings (2)
a - Screw Seal b - Tab In Cup c - Opening In Cup
1. Remove plugs from both exhaust elbows.
12. Reinstall the flame arrestor. a
Test Equipment The following equipment is needed to perform an emissions test on this engine: • Test Probes (Supplied in Kit). • Test Probe Collector (Testing Agency). • Exhaust System Analyzer (Testing Agency). b 71921
a a - Plugs (Port And Starboard Elbows)
73723
a - Exhaust Probe Collector b - To Exhaust Analyzer
Index 5E-14 – BODENSEE EMISSION FUEL SYSTEM
90-823226--1 996
2. Install exhaust elbow adapter fittings into elbows. Apply Loctite Pipe Sealant with Teflon to threads that go into elbow. Tighten securely.
NOTE: Be certain to place test probes and adapter fittings in suitable storage aboard the boat for use in the future.
3. Insert exhaust test probes into fittings and tighten securely. NOTICE TO OWNER/OPERATOR Your engine is equipped with special design features and special tuning to minimize the emission output from the engine. You should follow: • Recommended maintenance schedules particularly as to the ignition system.
a
71923
b
71919
a - Fittings b - Exhaust Test Probes
•
Proper engine tuning procedures to ensure these features remain in good operating order.
•
Proper steps to maintain the engine within specification.
The instructions in the Emissions Kit provide the necessary information to properly convert the engine to meet the applicable Bodensee Regulations. There is another item within the regulation that is beyond the control of Mercury Marine. This item is related to the fuel filling system on the boat. The requirements for the fuel filler neck are as follows: •
Must be designed so that it is impossible to use a fuel nozzle with an outside diameter of more than 23.6 mm.
•
The filler neck shall be durable and designed so that modifications are not possible.
•
A durable, legible plate shall be mounted on the boat near the fuel filler neck. This plate shall read: “UNLEADED GASOLINE ONLY”.
Any questions about the fuel filler neck requirement and availability of the required components should be directed to the boat manufacturer.
4. When exhaust emissions test is complete, remove test probes and adapter fittings and reinstall the plugs. Apply Perfect Seal to threads before installing. Tighten them securely.
Index 90-823226--1 996
BODENSEE EMISSIONS FUEL SYSTEM - 5E-15
THIS PAGE IS INTENTIONALLY BLANK TO ALLOW FOR CORRECTIONS OR ADDITIONS AT A LATER DATE
Index 5E-16 – BODENSEE EMISSION FUEL SYSTEM
90-823226--1 996
