Quantum Fuel Systems Releases New Fuel System Solution for LS/LT/EFI Swapped Square Body Trucks
Ventura, Calif. (April 22, 2022)– Over the last decade, 1973 – 1991 Chevy and GMC C/K pickups, known as “Square Body” trucks, have made a dramatic comeback in the performance and restoration industries. Specifically, LS and Gen V LT swaps have created a trend that has an enormous following in the automotive community. For years, owners and installers have been sourcing fuel system components from multiple manufacturers to satisfy the higher pressure needs of the LS and LT engines. Enter the fuel system hanger for ls swapped Square Bodies by QFS.
QFS LS Swap Fuel System Hanger
After months of research and development, Quantum has launched the highly anticipated QFS-H880 and QFS-H881 hangers. The H880 boasts 6AN inlet and return fittings designed to facilitate the installation of braided or push-lock type AN hoses without using compression fittings. The H881 features conventional barbed fittings, allowing the use of conventional slip-on style EFI hoses.
Both hangers facilitate the installation of the ACDelco EP381, Walbro/TI Automotive 255LPH, or AEM/Aeromotive/Quantum 340LPH fuel pumps without splicing connectors inside the tank. The Quantum hanger also offers the option to add preinstalled high volume fuel pumps.
Each hanger comes with two wiring pigtails compatible with the common ACDelco EP381, Walbro/TI Automotive 255LPH, and 340LPH intank pumps. Quantum Fuel Systems assembles each hanger to-order and pre-installs the purchaser’s chosen fuel pump prior to shipping.
All QFS fuel pumps and hangers are covered by Quantum Fuel Systems’ Lifetime Warranty.
Vehicle Compatibility:
1973-1991 Chevrolet & GMC Square Body Trucks with LS/LT Swap
A Brief History of the Square Body: 1973-1987 Chevy & GMC C/K Pickup Trucks
When talking about iconic pickup trucks, the conversation will always steer towards one of the most successful lines in truck history. The longstanding Chevy and GMC C/K series that spans over six decades, from 1960 to 2002. But, there is a strong chance that a big part of that debate will focus on the popular third-generation 1973 – 1987 Chevy and GMC C/K models, known as Square Body trucks.
Square Body refers to the series of C/K trucks that debuted in 1973. They immediately rose to fame, paving the way for an impressive 14 years of continuous production — without any major redesigns. A wide variety of models were offered, including light, medium, and full-sized pickup trucks and SUVs.
Select Square Body models, such as the Blazer, Suburban, and dual-wheel pickups, continued production until 1991. But generally speaking, ’73 – ’87 is seen as the primary years of production for Square Body trucks.
C/K terminology is straightforward, with “C” denoting two-wheel-drive trucks, while “K” signifies four-wheel-drive variants. Meanwhile, the numerals 10, 20, and 30 represent weight class, breaking things down by half-ton, three-quarter-ton, and one-ton, respectively. For example, a C10 model is a two-wheel-drive half-ton pickup.
Interestingly, while the public quickly bestowed the nickname Square Body on the third-generation C/K trucks, it was officially known as the “Round Line” style by Chevy designers. However, compared to prior generations, its boxy body style lent itself to the colloquial name.
It was a radically different design from previous iterations of the C/K line. The new trucks aimed to improve visibility with larger glass areas and curved side windows. In addition, the windshield, door frames, and square wheel wells all feature rounded corners, hence the name “Round Line.”
What helped propel the Square Body’s popularity focused on creature comforts with more elaborate dashboards and interiors. A far more spacious cab was complimented by cushier seating, increased airflow, better insulation, and weatherproofing, which improved the driving experience.
Four-door crew cab options were also available on select models, making them appeal to wider audiences.
The Square Body also introduced an all-new chassis that offered superior ride quality. Longer wheelbases helped increase stability, while frames featured additional bracing. In addition, staggered rear shock absorbers and leaf spring geometry were revised, to name a few of the changes.
There were a total of five engine choices offered across the C/K range. 250 and 292 inline 6-cylinder engines were common in light-duty trucks, while others used 307, 350, or 454 V8 engines.
Square Body Popularity
Total production numbers for Square Body trucks are difficult to pin down. However, it is estimated that over 10 million units were manufactured, and plenty of fine examples are still on the road today.
Initially, these trucks were incredibly popular with tradespeople due to their robust nature, hauling capability, and variety of powertrain options. Their massive production volume made replacement parts easy to come by and relatively affordable.
In fact, most auto parts suppliers still supply common components for C/K models, despite their age.
QFS LSX/ LTX EFI SWAP 6AN FITTING FUEL PUMP HANGER AND SENDING UNIT FOR 1973-1991 SQUARE BODY PICKUPS
Fast forward a few decades, and the Square Body has moved from the role of a farm or construction workhorse to one of the darlings of the performance truck world. A thriving Square Body community exists where owners lovingly restore hot rod, mud bog, autocross and do anything imaginable to these trucks.
These are simplistic trucks that most home mechanics can build up in their garage, upgrading chassis, brakes, and engine components without serious modification. Combine a vehicle range available in high numbers with massive aftermarket support, and you generally have a winner on your hands.
The massive engine bays of C/K trucks are appealing for those going the performance route. Engine swaps for modern high-performance LS or LT engines are easy to net huge gains in horsepower and torque without too much trouble.
LS / LT Swap Solutions
Of course, if you’re doing an LS or LT swap in your 1973 – 1987 Chevy and GMC / K10 / R10 / C20 / K20 / R20 / C30 / K30 / R30 / V10 / V20 / V30 truck, you’ll want to install our LS/LT Swap Fuel Pump Hanger and Sending Unit. Our brand new 6AN/6AN hanger is a clean-sheet design meant to facilitate the installation of braided AN hoses without adapters and without splicing wires — saving you time, effort, and money.
Every kit comes with two wiring pigtails compatible with AC Delco EP381, Walbro 255LPH, and other 340LPH intake pumps. Quantum pre-assembled fuel pump hangers feature a lifetime warranty on the Quantum fuel pump and sending unit. This is the last hanger your LS/LT swapped Square Body truck will ever need.
There is no doubt that the truck market is seeing renewed interest in the third-generation C/K Square Body trucks. We’re excited to see how a new generation of owners will put their spin on them. For all of your fuel system needs on your C/K truck, be sure to check out our web store. All orders placed by 2:00PM PST ship the same business day!
SUMMARY
Chevy / GMC Square Body series spanned from 1960 to 2002
1973 – 1987 are the primary years of production for Square Body trucks
The numerals 10, 20, and 30 represent weight class, breaking things down by half-ton, three-quarter-ton, and one-ton, respectively
The Square Body introduced an all-new chassis that offered superior ride quality
Square Body has moved from the role of a farm or construction workhorse to one of the darlings of the performance truck world
Engine swaps for modern high-performance LS or LT engines are easy to net huge gains in horsepower and torque without too much trouble
Quantum Fuel Systems
For over 15 years, Quantum Fuel Systems has been manufacturing and distributing fuel system components for OEM and performance applications. Our mission is to manufacture fuel systems that are centered around longevity, accurate flow data, and hassle free direct fitment.
How to Diagnose a Bad ATV, Motorcycle, UTV/Side-by-Side Fuel Pump
Understanding the symptoms and how to diagnose a bad fuel pump on an ATV, motorcycle, or UTV/SxS is handy knowledge for any enthusiast and precisely what we’ll be discussing below. When a fuel pump fails to operate within its designed specifications, your EFI-powered vehicle can suffer in a few ways. Expect lowered performance, causing it to run poorly, or failing to start at all.
A properly functioning fuel pump is one of the many crucial components in your ATV, motorcycle, or UTV/Side-by-Side (SxS).
Quantum Fuel Systems specializes in high-quality direct OEM replacement fuel system and engine management components. All QFS products are backed by an industry-leading lifetime warranty. Every product in our extensive Powersports product line is designed to match the technical specifications of your vehicle.
We know how important it is for our customers to get back on the road or trail. Your orders are processed the same business day, and we offer free 2-day shipping in the United States with any purchase above $60. QFS has you covered with complete replacement kits, individual parts, specialty tools, and more.
Whether we’re talking about two or four-wheeled vehicles, testing a bad fuel pump, or issues related to your fuel system are similar. It doesn’t matter if you drive an Arctic Cat, Can-Am, or Polaris, ride a Harley-Davidson, Honda, or Husqvarna. Fuel pumps can fail anytime, anywhere.
What does matter is that you’re referencing your vehicle-specific service manual to confirm any necessary technical specifications, as those figures can change depending on the vehicle year, make, and model.
Luckily, troubleshooting a bad fuel pump follows the same general principles, and we’ll be covering a few basic and advanced methods.
QFS does not intend this article to be a strict guide. As always, we recommend that only those confident in their mechanical abilities perform maintenance, repairs, and diagnosis on their vehicles.
If you do not feel comfortable performing this work, please consult an authorized and licensed service technician.
Let’s dive into it with how to diagnose a bad fuel pump and review some tell-tale symptoms of an underperforming or failed fuel pump.
Not Starting/Won’t Idle
Not starting when all systems appeared to be in regular working order is a good indicator that fuel is not making it through the fuel system. If the engine does start but fails to maintain idle, that is another sign that the pump is on its way out.
Whining
All fuel pumps produce a low audible hum when operating. When they reach the end of their lifespan, you may notice a loud whining sound, pointing to a fuel pump motor stressing itself to function.
In-Tank Fuel Pump Assembly for 2016-2023 Polaris RZR Turbo
Surging occurs when traveling at a constant speed and feels as if your ATV, motorcycle or UTV briefly accelerates with no input from the user. Typically, excessive pressure buildup can momentarily deliver excess fuel. In this case, we strongly recommend replacing the pump and filters immediately.
Power Loss Under Load/Cut outs
Does your bike, quad, or SxS accelerate normally only to begin losing power as the rpm climb or at higher rpm? That is often a signal of a fuel pump that cannot deliver the correct amount of fuel pressure to meet performance demands. Alternatively, you may experience power cut-outs at random, demonstrating a fuel pump operating sporadically.
Diagnosing a Failing Fuel Pump
Pinning-down fuel issues can be complex, as fuel systems and electrical systems are interdependent. Problems with one system can cause the other to malfunction. Our goal here is to isolate variables and help you determine the root cause of your issues.
Before you turn a single wrench, start with the basics and confirm a few things:
Is there fuel in the tank, and does your fuel gauge (if applicable) register accurately?
Is your battery adequately charged, and does your electrical system appear to be fully operational?
Is the kill switch in the “run” position?
Is your bike, SxS, or quad in neutral?
If you’ve answered yes to all those questions and you’re still experiencing issues, then it’s time to start investigating.
Fuel Pump Won’t Prime
Fuel pumps can fail with or without warning. We go to fire up our ATV, motorcycle, or UTV; the engine cranks, and it simply won’t start. Our first step is to observe if the fuel pump is operational and “priming.”
Priming means that the fuel pump engages for a short time, pressurizing the fuel lines and providing adequate fuel flow for the injectors.
To test this, cycle your key to the “on” position and listen intently for an audible hum coming from the fuel tank. The hum should only last a few seconds.
If you’ve repeated this multiple times and don’t hear a mechanical whirring, chances are the fuel pump has failed or is not being supplied electricity.
If you are performing this test on a dirt bike (Motocross or Enduro) that doesn’t have a keyed ignition, press the starter button and quickly release, which will trigger the fuel pump and allow you to determine if the fuel pump is operational.
Check the Fuel System Fuses & Relays
Fuses and relays act as bridges for electrical current. If they fail, the current can’t reach its proper destination and provide power. Consult your service manual to access your fuse box and relays, and then remove them to inspect them for any damage visually.
A healthy fuse will have its metal “bridge” connected, and a functional relay will “click” when power is delivered. You can also use a multimeter to check the resistance of a relay or fuse, which is more accurate.
Confirming Your Fuel Pump Has Power
If your fuel pump is not priming, you must determine if this is an electrical problem or a fuel pump failure. To do that, you will need to gain access to your vehicle’s fuel pump assembly. Consult your model-specific service manual for instructions to perform this safely.
Once you have clear access to the fuel pump assembly, you will want to test if power is coming down to the fuel pump itself with a multimeter or voltage meter.
Disconnect the wiring from the fuel pump assembly. Again, you will need to consult your service manual and wiring diagram to determine which terminal connections to measure.
Once you’ve done that, confirm that adequate power is available by cycling the key to the “on” position and measuring the voltage — it should rise to the cited technical specification in your service manual, then fall to zero after a few seconds. If you don’t have power or insufficient voltage, you know that the issue is not related to your fuel system.
If all is in order with the wiring harness, perform a continuity test with your multimeter on the fuel pump itself. Locate the positive and negative leads going to the fuel pump and check if an electrical connection is capable.
If it isn’t, rest assured that the fuel pump motor is dead.
Pressure Testing a Fuel Pump
Pressure testing is crucial when faced with lean and rich conditions, power loss, or surging, as irregular pressure in your fuel system can cause these issues. This test requires one of the few specialized tools mentioned here since it will need a gauge with model-specific connections to be installed between the vehicle’s fuel pump and fuel lines.
Once you’ve determined your vehicle’s fuel pressure specifications and installed the pressure tester, cycle the key to the “on” position. Pressure must raise and hold at the required specification.
If that checks out, start the engine and increase the rpm gradually. Once again, pressure should not deviate outside the recommended range.
If pressure is excessively high, your pressure regulator has failed, and we offer replacement options. Conversely, clogged fuel filters can lower fuel pressure and create flow issues.
Inspect all relevant filters thoroughly, although we recommend replacing them during this type of service. To accurately diagnose a bad fuel pump, all other fuel system components must be thoroughly checked.
We Are Standing By For Your Order
You can order from Quantum Fuel Systems, Monday through Friday, 8:00 a.m. to 5:00 p.m. PT, over the phone or browse our extensive catalog. Be sure to contact use our support page for any detailed technical questions, and we’ll get back to you as soon as possible.
