Fast Flow Bilge Pump Installation Instructions

FAST FLOW emergency bilge pumps are designed for easy installation without removing the boat shaft and are available in various sizes to fit most vessels.  The pump has a split case and split impeller to allow installation without removal of the boat shaft.

Each 2" pump is shipped with shaft bushing inserts that fit the most common boat shaft diameters.  The impeller is pre-bored and the bushings will fit 1.0", 1.25", 1.50", and 1.75"  If the inserts are not the correct size, they can be bored by a machine shop to fit your shaft diameter.  Each impeller is shaped like a flywheel, factory balanced, and should not cause any shaft vibration.  If your boat shaft is larger than 1.75", it will require the next larger size 3" pump.  The impeller can be bored up from 1.0" up to 4.0" to fit your shaft. Every boat engine compartment is different and there are several approved methods for accomplishing a quality installation.

#1 Site Selection:
The ideal location for the Fast Flow emergency bilge pump is between the stuffing box and gear box in the engine compartment, making sure that there is sufficient room for the pump system and tie-down.

Alternate installation can be accomplished wherever there is room available on the propeller shaft.

First, install the lower pump case and measure for the mounting bracket.  It is best to "check fit" with the lower pump case and then mount the impeller to ensure that there is plenty of room for installation.

#2 Impeller Installation:
• Measure the exact shaft size and select the correct impeller bushing to provide a tight compression fit.
•  Insert the correct bushing into the impeller.
• Tighten the impeller allen screws alternately for an equal compression fit.
• To validate correct impeller installation: With a feeler gauge, measure and match the gap between the impeller halves.


#3 Pump Case Installation:
• Check rotation of the shaft, making sure that the impeller blades are turning toward the pump discharge.
• Center the pump case to the impeller.  CAUTION:  The impeller must not touch the housing.  Evenly and alternately tighten the impeller allen screws.
• Tighten the four (4) pump case bolts evenly and alternately.
• Firmly secure the fast flow emergency bilge pump case to the engine, transmission, or boat structure.

There are several methods for doing this:
• Ideally, the pump is attached with an aluminum angle bracket to the engine or gear box (first illustration at right).
• Some customers attach the housing to the engine foundation using an aluminum angle.
• Others attach the bracket to the keelson stringer supports.  Some brackets can be slotted to be moved up or down and on an angle to align with the shaft height.
• Another method is to install fiber-glassed marine grade hardwood blocks to permanently hold the pump case in proper position (second illustration at right)


#4 Hull Installation/Discharge Connections:
The discharge hose can be attached with either hard piping or with a flexible hose.  We recommend that safety Camlock hose fittings be installed on the male pipe threaded pump outlet.

The discharge hose hull fitting can be installed and attached to the hose. Below waterline thru-hull fittings with non-return valves are not an approved or acceptable installation!  

Install a quality stainless 2" thru hull or exhaust style fitting at least 2' above the waterline.  Ideally use an exhaust style fitting that has a spring loaded cover.  

We recommend using quality Camlock safety fittings at the pump and quality Tee Bolt-Clamps at the discharge.  It is best to double band clamp.  You may also permanently double band clamp the hose to the discharge fitting using POP ratchet style clamps.   All band clamps should be stainless steel.

CAUTION: It is important to secure the pump housing and double-check to see that the impeller is not touching the pump case.  Before starting the engine and turning the shaft, make sure the impeller is not touching the pump case.  Verify that the rotation is correct so that the pump blades spin toward the discharge of the pump.  Inspect the pump when the boat is moving forward to see that the impeller is spinning toward the pump discharge.

Fast Flow Pumps • 9700 Hwy 63 • Moss Point MS 39562

© Copyright 2020 Fast Flow All Rights Reserved

Phone: 228.475.2468

Fast Flow, LLC and Fast Flow Pumps manufactured pumps are protected under: 35 U.S.C., 37 C.F.R. and 18 U.S.C.  Fast Flow, LLC and Fast Flow manufactured pumps are covered by one or more of the following patents: United States Patent Number(s): 6,942,448; 7,442,003; 8,152,443; 10,138,891 Other Patents Pending, Domestic and Foreign