Gulfstream 400 parts & owner guide

Original feed circuit

The manual lists two parallel feed pumps with cooling fans, one accumulator, one Clark Pump and one membrane housing. Each feed pump has a separate control circuit. One pump gives efficiency mode; both give high-production mode. Prime pumps separately and keep both fans working.

Original controls

Gulfstream uses a one-wire salinity probe, automatic diversion, main power box and remote Pump 1 / Pump 2 / Backflush switches with Good/Reject lamps. Its timed automatic freshwater flush runs through carbon, solenoid and check valve. These controls are legacy electronics; they do not establish MPC or Remote Manual.

Record the installed labels

Record model/serial, pump and fan voltage, controller/board, Clark ratio, filter bowls, membrane labels and added Z-Ion/flush equipment. Model-labeled Parts ID maps help identify current codes; old hardware still needs revision and interface confirmation.

Match housing, seal and wrench

The model Parts ID labels FT-FTH-10 standard housings. That exact housing is absent from this catalog; no substitute is assumed. Standard wrench, black 10H and small three-piece references require confirmed physical family. Black 10H uses SO-FHS-10H; three-piece uses SO-FHS-3PCS10. Cartridge dimensions alone do not select a seal or wrench.

Original flush circuit

Gulfstream includes timed automatic backflush using ship domestic-water pressure, carbon, a solenoid/check valve and one feed pump. Confirm domestic water is available and follow the original stop/backflush sequence for the fitted system. This is not MPC five-day Auto Store.

Chlorine damages membranes. Identify carbon age, element and housing separately; sediment filters and Z-Ion do not remove chlorine.

One kit replaces one pump

Current 12V pump-and-heat-sink kit and 24V kit exclude the cooling fan. Bare-pump codes, heads, diaphragm drives, heat sinks and fan kits are different scopes. Model Parts ID pages label pump and fan kits, but actual voltage, ports, switch, revision and contents still need confirmation.

Pressure and power under load

Original feed cutout is 125 PSI. Diagnose air, filters, voltage drop, leaks and cycling before changing parts. Match actual pump/fan DC labels and original circuits; a newer switch-adjustment recipe is not automatically suitable.

Gulfstream’s main power supply, separate pump circuits, fans and flush/salinity electronics must be assessed together. A single pump kit is not a replacement for the pair.

Different main-module mounting

Gulfstream main module mounts horizontally and needs access above its hinged top for electrical service. The independently mounted Clark Pump has its own shock mounts and tube alignment.

Identify the installed single-rod pump

The original manual describes 10-to-1 force advantage. Read the actual pump identification before ordering. Confirmed 10% uses one 7/8-inch rod; a confirmed changed 7% uses one 3/4-inch rod and different center block/seals. No 15%, 20% or Pearson family is selected.

Different kit contents

10% distributor kit and 7% kit exclude spacer rings, top-end spool pistons, tools and instructions. Seal/O-ring kit and offshore kit have distinct contents. Confirm ratio, revision, service scope and kit overlap.

Old revisions need confirmation

The May 2024 rebuild manual describes improvements to older pumps. Shared drawings include multiple ratios and reversing-valve designs. Current codes and illustrated assembly quantities do not prove old interchangeability or package contents. Keep actual parts/photos for Spectra review.

Identify the actual element

2.5 × 40-inch seawater membrane kit supplies one element and replacement seals. Show it only after checking the actual element label and dimensions. Complete housing length is not membrane length; one kit is not a vessel or automatic whole-system quantity.

Match original caps and mounting

Original service describes black end caps and threaded aluminum rings. Modern end-plug kit and retaining ring require actual port, seal, vent and revision confirmation. No universal seal count is inferred for changed caps. Preserve the approved flexible mounting so the vessel can expand; do not clamp it rigidly.

Product and remote relief are different circuits

Original product tubing is 1/4-inch outside diameter and must remain unrestricted. Use the original product service routing; a generic shutoff valve can block flow. Avoid tank/manifold backpressure.

Gulfstream’s remote pressure-relief line is also 1/4 inch, but it is HIGH-PRESSURE tubing. It connects the panel valve to the Clark Pump’s stainless relief port. Never substitute low-pressure product tube or fittings.

Diversion conversion: both DC voltages

The 2022 chart lists KIT-MNF-BURDV12 for identified ECI/Alcon or Spartan diversion valves and explicitly permits both 12V and 24V. Its suffix is not the supply rule. Confirm actual body, connectors, adapter contents and discharge routing. It is not a complete Newport intake-manifold replacement for Gulfstream.

Flush coil versus complete body

KIT-SLN-ECISPO1 is a 12V ECI/Alcon flush conversion using an existing sound valve body. Body replacement has a different scope. Diversion and flush valves are not interchangeable. Unlisted 24V kit codes do not authorize a 12V substitute.

Confirm actual controls

Current manufacturer lists analog Legacy under manual Z-Ion candidate. Review a confirmed analog installation and full flush/trigger interface with Spectra. Existing catalog Deluxe/Cape Horn requirements remain visible. Gulfstream original automatic salinity/timer controls do not imply MPC or Remote Manual and do not automatically select MAN or AUTO.

Approve accessory power separately

Automated candidate is reserved here for an identified already installed MPC-5000 with approved interfaces. Any retrofit also needs fitted freshwater flush and a separately approved 12/24V DC accessory supply. Feed-pump voltage alone does not approve accessory power; changing it clears the approval selection. No direct AC or 48V.

Service a fitted generator

Confirm the generator and control box before showing service parts. Combined bowl and rod differs from loose bowl/rod scope; do not automatically add a separate rod. A service assembly does not supply a complete retrofit. Z-Ion does not remove chlorine or prevent freezing.

Record a normal baseline

Inspect fine-mesh strainer, replace loaded sediment elements and monitor pressure, flow and voltage under load. Keep heat sinks and fitted fans clear. Mechanical GPH flow is read at the middle of the original indicator ball. Diagnose actual gauge position, air, leaks and pump faults before cleaning.

Use current chemical roles

SC-1 is storage compound; SC-2 is alkaline biological-fouling cleaner; SC-3 is acid mineral-scale cleaner. Old manuals use outdated SC-1 scale-cleaning names. Santa Cruz page 18 also includes unrelated 400/1000 volumes and automatic-button instructions; that text does not establish automatic controls. Never mix SC-2 and SC-3 or use cleaners for storage. No numeric dose is supplied.

Flush, storage purge and freezing

Use nonchlorinated water and the procedure approved for actual hardware. Original manuals reject sodium bisulfite/metabisulfite because of pump damage. Chemical circulation and stored-system purge use the prescribed depressurized service path; do not confuse a normal freshwater-flush cycle with chemical purge. Keep product out of the tank until the purge and water checks are complete. SC-1 and Z-Ion do not prevent freezing; obtain the fitted-system winterizing procedure.

Cruise Kit B contents

KIT-BCK-B supplies three 5-micron, three 20-micron, one carbon and two SC-1. These are spare quantities. Manufacturer lists Santa Cruz and Gulfstream MPC; the wording does not prove MPC on a 1999 Gulfstream or an extra Santa Cruz filter housing. Match actual housings and current contents. Santa Cruz original shipping/kit descriptions give different counts; current contents are stated here.