RV Water Pump: Diagnose, Maintain, or Install
Start with the right decision
This hub covers the Shurflo 4008 RV By-Pass Pump. If your pump is not a 4008, stop and use its own manual.
| If you need to… | Use this section |
|---|---|
| Find out why the pump is not building pressure | Diagnose |
| Sanitize a known tank size | Maintain |
| Check a planned install before mounting | Install |
Diagnose
Start with the pump model and the plumbing. If the pump is not a 4008, stop and use its own manual. If the pump is a 4008, the full symptom sequence is on the water pump troubleshooting page.
Do not raise pressure blindly. Fix outlet leaks before adjusting the pressure switch.
Maintain
Use the manual’s ratio, not a guess. The base dose is 2 ounces of bleach per 15 gallons of tank size.
| Tank size | Bleach dose | Contact time |
|---|---|---|
| 15 gallons | 2 ounces | Four hours, or double the concentration for one hour |
| 30 gallons | 4 ounces | Four hours, or double the concentration for one hour |
| 60 gallons | 8 ounces | Four hours, or double the concentration for one hour |
| 100 gallons | about 13.3 ounces | Four hours, or double the concentration for one hour |
Use 2 ounces of bleach per 15 gallons of tank size. Allow four hours of contact, or double the concentration for one hour. Do not guess the dose; use the tank label. Stop and find the tank label when tank size is unknown.
Install
Run this check before mounting the pump.
| Check | Requirement | Stop condition |
|---|---|---|
| Model | Shurflo 4008 | Stop if the pump is not a Shurflo 4008. |
| Electrical | 10 Amp circuit | Stop if the circuit cannot supply 10 amps. |
| Plumbing | Strainer and flexible high-pressure hose; no rigid or plastic pipe at the ports | Stop if the plumbing is restricted or rigid. |
| Controller | Intellitec controller rated 10 or 15 amps | Stop if the controller is rated 7.5 amps; use a 10/15 amp controller or high-amp relay. |
| Duty | Intermittent duty only | Stop if the plan is continuous reverse-osmosis. |
Check a 10 Amp circuit, a strainer, flexible hose, and a controller rated 10 or 15 amps. Stop if the controller is rated 7.5 amps; use a 10/15 amp controller or high-amp relay. Do not use the pump for continuous reverse-osmosis filtration; it is intermittent duty only. Stop if the plan is continuous reverse-osmosis.
Five-Point Replacement Check
Before buying a replacement for a Shurflo 4008, run these five checks against the RV as it sits. Each check either clears the replacement or stops it.
| Check | Question | Pass | Stop |
|---|---|---|---|
| Controller | What if the controller is 7.5 amps? | Controller rated 10 or 15 amps, or a new controller or high-amp relay is in hand | Controller rating cannot be read |
| Duty | Can the 4008 run a reverse-osmosis system? | Pump is not feeding an RO filtration system | Replacement is the same 4008 for RO duty |
| Circuit | What circuit minimum is required? | Minimum 10-amp circuit confirmed | Circuit is below 10 amps |
| Plumbing | What hose should be used? | Flexible high-pressure hose available | Only rigid pipe is available |
| Scope | What if the pump is not a 4008? | Model confirmed as Shurflo 4008 | Model cannot be identified |
Controller
If the Intellitec Pump Controller is rated at 7.5 amps, use a new controller or a high-amp relay before installing the pump. Stop if the controller rating cannot be read.
Duty
The Shurflo 4008 is designed for intermittent duty only and must not run a reverse-osmosis filtration system. Do not use the Shurflo 4008 for that duty; choose an intermittent-duty pump. Stop if the replacement is the same 4008.
Circuit
Confirm a minimum 10-amp circuit. The pump requires a minimum 10-amp circuit. Stop if the circuit is below 10 amps.
Plumbing
Use flexible high-pressure hose on the pump. Stop if only rigid pipe is available.
Scope
These requirements apply to the Shurflo 4008; other pumps need their own manual. Stop and use the documentation for the installed pump. Stop if the model cannot be identified.
Source: Shurflo 4008 Installation & Maintenance Manual
Source
All details above come from the Shurflo 4008 manual: https://www.dyersonline.com/amfile/file/download/file/1301/product/1354/
Related RV owner guides
Practical RV guides from an experienced owner. Motorhomes, travel trailers, truck campers — we have owned them, maintained them, and written the guides we wish we had found when we started.