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5 Ways To Bulletproof Your Fuel System

5 Ways To Bulletproof Your Fuel System

Outdoor recreation is booming, which means more people are using their Powersports vehicles. Motorcycles, dirt bikes, ATVs, UTVs/Side-By-Sides, snowmobiles, and personal watercraft are racking up hours across the United States as new riders and families join in on the fun. Motorcycle sales alone were up nearly 10 percent in 2021, hitting their highest levels in 15 years. 

All that time out on the road, trail, or water does add up, and responsible owners know that to get the most out of our vehicles, they need to keep up with regular maintenance. Even the most diligent owners and DIY mechanics overlook their fuel systems until there is a problem. 

We’re going to go over five easy ways to bulletproof your fuel system and ensure it’s in good working order, giving you peak performance, fuel mileage, and reliability. Don’t think these tips are exclusive to your motorcycle, quad, or UTV — these maintenance suggestions apply to any car, truck, or RV equipped with Electronic Fuel Injection (EFI). 

Quantum Fuel Systems is the authority in high-quality direct OE replacement fuel system components. All QFS-branded parts are backed by an industry-leading lifetime warranty and are designed to meet or exceed OEM quality. Visit our catalog for all your fuel system needs.

1. Keep Your Fuel Tank Full

This is one of the most straightforward tips of the bunch and applies to any standard in-tank fuel pump conveniently located inside your fuel tank. In-tank fuel pumps are constantly submerged in liquid fuel, helping lubricate and cool one of the hardest working components in your fuel system.

Radiant heat from the engine and the fuel pump’s electric motor will increase fuel temperature as your fuel load drops, putting more stress on the fuel pump and causing it to work harder, leading to premature failure.

While today’s gas prices certainly aren’t making things easy for consumers, one of the simplest ways to maintain the health of your fuel pump is never run on empty. Always try to stay above ¼, and your fuel pump will thank you for it. 

2. Don’t Fill Up When The Fuel Delivery Truck Is At The Gas Station

We know that this suggestion might sound like an urban myth, but there is nothing subtle about how a tanker truck dispenses fuel into gas station holding tanks. Thousands of gallons of fuel are dumped into a tank rapidly, stirring up sediment, debris, and even water resting at the bottom.

None of that material is suitable for your fuel system, and it’s best to let the sediment settle before filling up at that station.

3. Inspect Or Replace Filters And Strainers

Filters and strainers are the first and last words in protecting your fuel system. Without them, harmful particulates can mix with a sticky fuel remnant known as gasoline varnish, wreaking havoc on the precision components found in the fuel system and engine. Clogged or damaged filters and strainers can lead to performance loss and premature wear on your internal components.

The first line of defense your fuel system has is a fuel pump strainer that prevents sand, dirt, and foreign objects from clogging or damaging parts. Once a strainer has absorbed all the material it can, it will restrict flow, which puts unnecessary strain on the fuel pump. 

Fuel filters serve the same purpose as a strainer and are typically further up in the fuel system chain. Filters defend engine components, such as your fuel injectors and sensors, from anything that manages to get past the fuel pump strainer.

A clogged filter is detrimental to proper fuel flow, and foreign objects are equally harmful to the rest of your fuel system, clogging small passages and causing performance loss or outright mechanical problems.

Always remember that street-focused motorcycles, cars, and trucks will have much higher service intervals than anything off-road oriented. The harsher off-road environment can quickly introduce dust, dirt, and debris into the fuel system, making maintenance schedules far more frequent on dirt bikes, ATVs, and UTVs/Side-By-Sides.

Be sure to reference your model-specific manual for exact mileage/hour figures. Our complete line of filters and strainers are designed to withstand harsh fuel additives and ethanol-based gasoline, ensuring filtration and performance.

4. Clean Your Injectors

Fuel injectors do precisely that: Inject fuel into the engine throttle body or cylinder, allowing a precise amount of atomized fuel to be delivered for proper combustion. Injectors are electronically controlled valves operated by a solenoid that must open and close with extreme accuracy.

Over time, deposits can restrict their spray pattern, causing symptoms like performance loss, decreased fuel economy, rough idle, and misfires. 

Cleaning injectors do not apply to low-mileage/low-hour vehicles unless they’ve sat unused for long periods. Any late model or high-mileage vehicle can benefit from a thorough injector cleaning.

There are plenty of aftermarket tools, solvents, and fuel additives to help clean your injector system. These products remove varnish, build-up, and deposits from small passages, allowing the injector spray pattern to function as intended.

The most effective way to clean any delicate precision component is using ultrasonic cleaning tools. At-home mechanics can purchase specialized tools, but many authorized service shops have the equipment to perform this task.

Ultrasonic cleaning uses high-frequency sound waves transmitted through a liquid to scrub and clean surfaces through a process known as cavitation. These tools are incredibly adept at removing build-up, oils, and other deposits that might obstruct the spray pattern. 

If you find that your injectors are beyond repair, QFS sells direct replacements from reputable brands such as Bosch, Injector Dynamics, RC Engineering, and Siemens Deka. We also stock PnP adapters and wiring harnesses built to fit seamlessly with their respective fuel injector.

5. Maintain Electrical Components

Electrical gremlins are tough, especially when you’re out having fun on your bike, UTV/Side-By-Side, or personal watercraft. Inspecting and double-checking electrical connections is as crucial as changing fluids according to cited service intervals, although many owners don’t make it part of their routine. 

Loose or damaged connectors and wiring can lead to problems beyond intermittent issues. These bad connections could lead to a total failure of a fuel pump, pop fuses or relays, and leave you stranded.

During your routine maintenance, make it a habit to inspect all electrical connections, especially those on off-road oriented vehicles that are subject to running in dirty environments and taking lots of abuse. 

It’s also advisable to test critical electrical systems with a voltage meter to detect problems before they cause harm. While you’re there, hit the electrical connections with some contact cleaner to clean the conductive surfaces.

Lastly, those doing long-distance rides or drives should always look at the most common fuses and relays in their fuse box and carry a spare.

At the most basic level, ensuring your battery is healthy and fully charged is a good place to start. Depending on your charging system, a weak battery can reduce fuel pressure and create lean conditions.

Always keep batteries maintained with a modern “smart charger” that not only maintains a full charge but reconditions your battery and provides a long service life.  

Have Any Questions? Give Quantum Fuel Systems A Call Today!

Quantum Fuel Systems is open Monday through Friday, 8:00 a.m. to 5:00 p.m. PT. We are happy to assist our customers over the phone, or you can browse our extensive catalog. Have any technical questions? Our trained support team will get back to you with answers.

How to Diagnose Dual Fuel Pump Problems on Outboard Engines

How to Diagnose Dual Fuel Pump Problems on Outboard Engines

Modern outboard motors are reliable pieces of equipment capable of propelling our vessels for hundreds of service hours. As robust as they are, fuel pump troubles can still occur.

Today’s intricate Electronic Fuel Injection (EFI) marine engines often add complexity with features like dual fuel pump systems, making pinpointing fuel-related problems difficult. We will discuss how to diagnose fuel pump problems on outboard motors, specifically those with dual fuel pump systems.

If your outboard motor is suffering from a loss in performance, unable to run reliably, or won’t start at all — you may be dealing with fuel pumps that have failed.

We strongly suggest referencing the model-specific service manual for your outboard motor to confirm all technical specifications when performing diagnostics. Those figures can change depending on the year, make, and model of your outboard motor. 

If you do not feel qualified performing the following diagnostic work, please consult an authorized and licensed service technician.

Quantum Fuel Systems is a leader in direct-OEM replacement fuel system components, providing high-quality repair parts for major marine brands, such as Evinrude Outboards, Honda, Mercury Marine, Suzuki, Volvo, Yamaha, and more. QFS offers complete replacement kits, parts, and specialty to tools to get you back out on the water.

An unmatched lifetime warranty backs QFS products, and all orders are processed on the same business day, with free 2-day shipping within the United States for any order above $60. 

What Is a Dual Fuel Pump System?

A dual fuel pump system relies on a low-pressure and a high-pressure fuel pump to perform separate tasks. A low-pressure fuel pump lifts fuel from your fuel tank to your outboard motor’s Vapor Separator Tank, also referred to as a Fuel Supply Module, depending on the manufacturer. 

VSTs/FSMs house all sensitive fuel-delivery-related components. Often, you may see the low-pressure pump described as a “lift pump” because of its primary function. It does not pressurize the EFI system or injectors in any capacity.

Once fuel is transferred into the VST/FSM, the high-pressure fuel pump can pressurize the high-pressure fuel rail and allow your EFI system to function as intended. 

It is essential to recognize that high and low-pressure fuel pumps have unique technical specifications because of their different purposes in the system. However, the same testing procedures apply to both fuel pumps, and it simply means you will repeat the processes for each pump. 

Typically, both fuel pumps in a dual-pump system will not fail simultaneously, meaning that owners can save money by knowing how and when to upgrade with high-quality QFS fuel pumps.

Symptoms of a Bad Outboard Motor Fuel Pump


Before diving into diagnosis methods, we will outline a few common symptoms related to bad fuel pumps. These are general symptoms and are often seen in various automotive, marine, or Powersports applications.

Failing to start or Maintain Idle

An engine that fails to start when electrical, starting, and filter systems appear to be in good condition usually indicates that fuel is not reaching the EFI system. In most cases, that means a fuel pump has ceased working entirely.

Similarly, an engine that starts but cannot maintain a steady idle is another sign that the pumping system has a fault. 

Losing Power When Throttling Up

Throttling up and raising engine rpm puts more stress on the fuel system, demanding greater fuel pressure and flow to meet performance requirements. While your outboard engine might behave normally at low rpm, it may stall, sputter, or lose power as the rpm climbs, signaling that the fuel pumps are operating inconsistently and unable to keep up. 

Increased Engine Temperature

Your outboard motor could appear to be working normally and propelling your vessel as it should, yet it seems to be running hotter than average. Often, this situation can signal that the optimal fuel/air mixture isn’t achieved, due to a restricted or underperforming pumping system.

Diagnosing a Bad Dual Fuel Pump System

Resolving fueling issues is done through the process of elimination and can be tricky since electrical and fuel systems are related. These tips should help you narrow down the possibilities and uncover the cause of your problems.

Most of the diagnostic suggested here will only require you to listen, observe, and use basic hand tools (screwdrivers, sockets, and pliers). Advanced diagnosis methods will require specialized tools such as a pressure testing gauge and a voltage meter or multimeter.

We also encourage wearing eye protection and nitrile gloves when dealing with fuel and fuel-related components.

Start With the Basics

  • Confirm there is fuel in the tank and that the fuel gauge is registering accurately.
  • Confirm that your electrical charging system is in good health; all connections are free of corrosion and buildup, all fuses are intact, and the electrical system is functional.
  • Confirm all fuel system components are in working order; check that filters, screens, fuel lines, connections, and seals are adequately maintained.

Listen for Fuel Pump Priming

In most cases, your fuel pump(s) will quit working unexpectedly. When faced with a situation where you go to fire your boat up, it cranks but won’t start; we’ll need to pause and listen if the fuel pumps are priming. 

Priming is when a fuel pump engages for a short period. Note that on a dual pump fuel system, both pumps will prime — the low-pressure pump draws fuel into the VST/FSM, and the high-pressure pump primes the EFI system.

Testing this is simple. Cycle the ignition to the “on” position and listen closely for an audible whine or whirring coming from the outboard motor. This whirring sound will last a few seconds. Repeat this process multiple times and confirm whether or not you hear a mechanical whine. 

If nothing is heard while cycling the ignition on, the fuel pumps may have failed, or the pumps may not be receiving electrical power.

Inspect the VST/FSM Assemblies

Most outboard motors use VST/FSM assemblies to house fuel-related components such as a limited amount of fuel, a float or float switch, various filters, and a pressure regulator. These designs and specifications will change with the make and model of your particular engine, so please reference your service manual for exact information.

The low-pressure fuel pump draws fuel from the tank into the VST/FSM. Gain access to the VST/FSM and inspect whether or not fuel is being deposited into the VST/FSM container.

Once again, always refer to your authorized service manual for proper removal procedures.

If no fuel is present in the VST/FSM, chances are the low-pressure fuel pump is malfunctioning and not delivering fuel. If an adequate amount of fuel is available, the problem could be with the high-pressure fuel pump.

Check for Electrical Power to Fuel Pumps

Generally, if your fuel pumps are not priming, you will want to confirm that they’re receiving electrical power. These tests will help determine if your issues are tied to the electrical system or the fuel pumps.

Using a multimeter or voltage meter, we can inspect the various electrical connections and determine if the required amount of electrical current is traveling down through the wiring harness to each fuel pump. Since we are dealing with dual pump systems, you’ll need to repeat the steps for both the high and low-pressure fuel pumps.

Consult your service manual and wiring diagram to determine which terminal connections to measure. Remove the relevant terminals from the pump and cycle the key to the “on” position while measuring the voltage.

The voltage should rise to the stated technical specification in your service manual and return to zero after several seconds. If no voltage or insufficient voltage is measured at these terminals, your problem is likely electrical.

If your wiring harness is delivering power, then it’s time to perform a continuity test on the fuel pumps themselves with your multimeter. A continuity test confirms if an electrical circuit can be completed and is impossible when a fuel pump’s electric motor burns out. 

Pressure Testing Fuel Pumps

Pressure testing is helpful if your outboard motor is experiencing sputtering or stalling since inconsistent pressure in your fuel system can create these problems. Luckily, most modern outboard motors feature threaded testing valves on the high and low-pressure sides of the fuel system.

A pressure gauge can be acquired from any authorized dealer or marine retailer. 

Refer to your service manual for fuel pressure specifications, install the pressure tester, and then cycle the ignition “on.” The pressure should rise and maintain at the cited specification.

Start the engine and increase the throttle slowly while noting if the fuel pump can maintain pressure within its recommended range. Repeat the process for both fuel pumps. 

If pressure is abnormally low or nonexistent, then you’ve most likely discovered your problem.

For reference, pressures higher than the recommended range indicate that the pressure regulator is defective. By the same logic, clogged fuel filters and leaking fuel lines can decrease pressure significantly.

Inspect all components thoroughly, and we offer complete replacement kits for all major brands, including fuel pumps, seals, and filters, to get the job done.

Order Now

Quantum Fuel Systems is open Monday through Friday, 8:00 a.m. to 5:00 p.m. PT. Place orders over the phone or browse our extensive catalog. For technical questions, visit our support page, and we’ll get back to you as soon as possible. 

  • Identifying problems with dual-pump setups. Many outboard systems consist of high & low pressure fuel pumps in a single system. Users can save money by identifying which pump is causing issues.

As far as the dual pump system goes, its crucial to test them out independently. For the high pressure pump, the standard procedure for testing the fuel pump (electric, pressure test, etc.) will suffice for determining if that fuel pump needs to be replaced. Pressure test the low pressure pump is more difficult due to its nature of it being a low pressure pump. They suggest the electric connection test as the most efficient way to test the low pressure pump.

Summary


  • Understanding the symptoms and how to diagnose a bad fuel pump on an ATV, motorcycle, or UTV/SxS is handy knowledge for any enthusiast
  • When a fuel pump fails to operate within its designed specifications, your EFI-powered vehicle can suffer in a few ways — robbing performance, causing it to run poorly, or failing to start at all
  • Pinning-down fuel issues can be complex, as fuel systems and electrical systems are interdependent
  • Priming means that the fuel pump engages for a short time, pressurizing the fuel lines and providing adequate fuel flow for the injectors
  • Pressure testing is crucial when faced with lean and rich conditions, power loss, or surging
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