In the grand scheme of things, adding EFI to a classic car or truck is relatively new. Sure, people have been doing it for years, but it was not until that last several when the upgrade became so easy, anyone can do it. Case in point, I did it to my C10 in February of 2018. The Sniper kit was easy to install and has been a great addition to the truck. But a lack of time caused me to never address an issue with the fuel system — fuel slosh. With the help of Tanks Inc. I am finally able to remedy that situation.
When I added the Holley Sniper EFI to my truck, I installed the kit as the directions stated. This means I used the supplied inline fuel pump. I have no issue with an inline fuel pump. These pumps are okay to use and they are relatively inexpensive and fairly easy to install. Keep in mind, they should be mounted no more than 24-inches from the gas tank. It is also highly recommended they be mounted at a height close to the bottom level of the gas tank. Mounting them higher (above the fuel level) could cause poor performance and premature failure. As an aside, some people do claim they can be noisy when operating but I think a lot of that has to do with improper mounting.
With the Tanks Inc. tank, I can now add an in-tank fuel pump. As I stated, the inline fuel pump works fine, but it can get a little warm while keeping the fuel system under constant pressure. One way to remove some of that heat from the system is to keep the pump submerged in the fuel within the tank.
Fuel Issues To Combat
As I state in a previous article I wrote about upgrading your fuel system for EFI, I remark, “When your car or truck was running a carburetor, if the tank was low on fuel, the subsequent fuel slosh that occurred while stopping or initiating vehicle movement which uncovered the fuel pickup, was not an issue. That is because, if the fuel tank got low and fuel slosh caused the fuel-pick-up tube to temporarily become un-submerged, the carburetor’s fuel bowl carried a small reserve of fuel that would continue to feed the engine. Even if the fuel pickup is uncovered momentarily, the engine’s vacuum could still pull fuel from the carburetor’s fuel bowl. But in an EFI situation, the results are drastically different.
During that same fuel-slosh scenario when running EFI, there is no ‘reserve’ fuel supply. The EFI system relies on constant pressure supplying fuel from the tank. If the pickup is not fully submerged in fuel — even for a moment — the EFI pump will suck air. This is noticed when the engine stumbles — or worse — stalls.
The Fix Is In
My fix for this condition is to upgrade my C10 with a new tank designed for an EFI application. Some of you might be asking, “what’s the difference”? A quick look inside an EFI-specific tank reveals it has baffles or a sump that will always keep the fuel pick up submerged in fuel. In short, this sump does not allow fuel to leave the fuel pick-up area when stopping or initiating vehicle movement.
A Matter Of Sensing
If you have upgraded your fuel tank and have an incorrect fuel gauge reading, there are ways to test the sending unit to see if that is the culprit. A classic Chevy has a 0-90-ohm fuel sender and gauge. When the sender is at the empty position, the rheostat is not creating any resistance to ground (near zero ohms). When the fuel sender is in the full position, the rheostat is creating 90 ohm of resistance.
Tanks, Inc. has been manufacturing replacement fuel tanks for many years. During this install, I found the quality, fit, and finish of the tank to be excellent. “This is a die-stamped tank,” says Justin Somerville of Tanks Inc. “A top and bottom are die-stamped, along with internal baffles that are also stamped. We then roll-weld the tank together and powdercoat the outside of it.” But, there are even more benefits to a new EFI-compatible tank.
“We put internal baffles inside our stamped tank,” says Justin. “No other manufacturer goes through the expense of making the tooling specifically for an EFI application that includes internal baffling. This is not just a repurposed OEM tank. Also, we have many options to get exactly what a customer requires. We have ten sender options for this tank, along with seven different fuel pump options. Regardless of the gauges and engine being used, we probably have a solution.”
What Pump Do I Need?
If you think you need a fuel pump that delivers a specific pressure, think again. A pump delivers flow, and that is all. Any restriction in the line — or the inclusion of a regulator — will create the pressure needed. The pump needs to supply the necessary flow to maintain the required fuel pressure for a given application. when regulated at the required pressure to fulfill the needs of that application. Choosing the correct fuel pump can seem like a confusing proposition, but it doesn’t need to be cause for alarm. When I started this upgrade, I reached out to Tanks Inc. and was given a recommendation of using PN: GPA-4. This is an in-tank module “kit” with a high-flow fuel pump for engines delivering up to 630 horsepower. In the sidebar below, Tanks Inc. even has some criteria to help you with your decision.
All Pumped Up
When selecting a fuel pump, Tanks Inc. recommends you consider three factors: How much horsepower your engine will produce, what fuel pressure is required for your engine, and how much voltage is supplied to your fuel pump when the engine is running.
The amount of horsepower will determine how much fuel flow is required to support that engine. As horsepower increases, so does the volume of fuel required to support that power. A good estimator of volume-to-power is approximately 10hp per gallon. For example, if your pump flows at 50 gallon-per-hour (gph), it should be able to support a 500hp engine (50 x 10 = 500). However, to actually know the gph needed, you must also consider the fuel pressure required for your engine.
Different engines require different fuel pressures. For example, a carbureted engine typically requires around 7psi. A typical LS engine runs on about 60psi. The Sniper is designed to run with 60psi. Furthermore, if you are running boost, the pressure required for your engine may increase under load.
It is important to know what max pressure your engine will require because fuel pressure has a large effect on how much flow a pump can produce. A fuel pump will flow at its highest volume when there is no pressure (free flow). As fuel pressure increases, fuel flow decreases. Every pump has a different flow volume at a given pressure. Because of this, it is important to look at a flow chart of whatever pump you decide to buy.
Gauging The Results
Like many OE tanks, the truck’s original tank incorporated the fuel-gauge sender as part of the fuel pick-up module. The new tank has a separate mounting location for the sender, divorced from the pick-up module. This requires a new sending unit be employed. Tanks Inc. offers two options when ordering a sending unit. One is a traditional “beam” style, and the other is a tubular style. The beam style is a tried-and-true unit that has been around for decades. It’s accurate, reliable, and rarely goes bad. However, the tubular style might be a better choice for you.
The revolutionary tube design has some benefits over the traditional beam style. First, this floatless fuel sender is ideal for applications where a conventional beam style will not fit due to clearance issues. It’s available in various lengths. The tubular design also acts as a damper to prevent the gauge from moving erratically because of fuel slosh. This floatless fuel sender is also not susceptible to any side-to-side motion. This means it has no moving parts to wear out. It is top mounted and utilizes the aftermarket-standard SAE 5-hole mounting flange and comes complete with gasket and mounting hardware. This sender is available in ohm ranges of 0-30, 0-90, 73-10, 240-33, and 10-180.
Changing the fuel tank is not a difficult task. You can do this in your driveway with a hydraulic jack, a couple of jack stands, some hand tools, a few fittings, and a couple of feet of rubber hose. Removing and installing a fuel tank is different for so many vehicles, so I’m not going to get deep into my swap, but rest assured, it can be accomplished in a morning or afternoon.
While the new Tanks Inc. tank was not meant to give the truck more power, it is nice to no longer be a victim of fuel slosh while driving. This alone has definitely made driving the truck a lot more enjoyable. That being said, since the fuel system is capable of delivering adequate fuel to a 630hp engine, we all know what needs to be upgraded next…