TPI Components-Fuel System
Converting to tpi will mean you'll have to have a O2 sensor exhaust manifold. If you choose to use aftermarket headers, you'll need to have a sensor bung welded in the collector. Be aware that this location is further downstream from the hot exhaust needed to heat up the sensor and activate it, if its to far away or you get error codes regarding the O2 sensor malfunction, and you may have to add a heated sensor.
Pictured above is the 3 wire heated O2 sensor. This particular one is from a 1993 Chevy Lumina 3.1L .More common on he later vehicles is the 4 wire O2 sensor, which an extra ground is added for the feedback directly from the sensor. It will work with your tpi system with headers. If possible, obtain the female end connector that goes back to the harness. The terminal letters on the connectors is as follows (A) 12V power (B) ground (C) sensor output to ecm. Always go by terminal letters, not wire colors. Connect the 12V power to a vehicle ignition on power source, preferably to the wire that powers your HEI or remote coil (HEI) , since it is a heavy gauge wire, install a inline 10A fuse to O2 power wire to protect it. Do not connect it to your fuel pump power wire or any other 12V power source from your ecm.
Also be aware of your local emission laws regarding the headers to be certified and to have all emission devices that are required such as air tubes and catalytic converter. If you choose to use stock manifolds and don't have the one with the O2 sensor fitting, you can do one of two things. 1) Purchase a manifold through a salvage yard or Chevrolet, the manifold is a over the counter replacement and the number is 14060629. Or (2) you can have your manifold modified to accept the sensor. Another option is to have a O2 sensor bung welded in the pipe just below the exhaust manifold flange. Having the O2 sensor close to the conversion point will negate the use of a heated O2 sensor, simplifying the installation.
Single wire O2 sensor, common on the early fuel injected vehicles.
Another thing that must be done is to add a fuel return line to your gas tank. The best way I found and the cheapest is to get a line from a donor car that is the same make or at least the same body style. The supply line must be at least 3/8". The return line must be at least 5/16". Where flexible line is required, use only fuel line that is fuel injection approved.
Use steel line for your fuel line when it is exposed, such as under the vehicle. Even though aluminum fuel line is available, it requires special handling, installation of fittings to insure there is no stresses, which will lead to failure.
WARNING! WARNING! WARNING! WARNING!
Don't think even for one second that you can use regular rubber fuel line and save a few bucks. Regular fuel line for carbureted and tbi applications is for fuel pressures that won't exceed 15 psi. Fuel injection (multiport and tuned port) pressures exceed 40 psi and the fuel line is specifically designed for this. It will say so on the package and is imprinted on the hose itself. Failure to heed this will result in fire, property damage and may even cost you your life!
You'll have to have a fuel line fabricated to your sending unit assembly to dump the return fuel back into the tank. This line should be at least 5/16" in. diameter and should extend long enough to be about the same height of the fuel pick up strainer.
There are different ways you can supply the fuel via fuel pump. One way is to use and modify your stock tank to accept the tpi fuel pump. There are some businesses that may be able to do this for you, you'll have to call around and do some research. When doing a modification on your stock tank, see if its possible to add a internal baffle to keep the fuel from being sloshed around, especially during cornering and causing the fuel pick up from sucking air and possibly stalling the vehicle. The fuel pump unit itself can be found in many GM tbi and pfi vehicles. You'll have to make sure the tank and pump assembly are compatible in height to be installed. If you are using a unit from a tbi car, you'll have to change the fuel pump to a tpi pump. Just remember the tbi pump is only rated for 9-15 psi and will not work in a tpi car. Be sure to get a new strainer for the pump.
Typical parts, not shown is the "sock" filter that goes on the bottom of the pump (A). Don't even think about running a pump with out it. The sock filter is designed to keep hard particles from being sucked into the internals and destroying the pump in a very short time. If you buy a new pump, the warranty requires you to purchase one and it is very cheap insurance ($3-5). (B) is the pulsation dampener (C) is the fuel gauge sender (D) is the tank float connected to the sender (E) is the top cap and locking ring. (F) is the electrical connections for the pump power, ground and sender. (G, H and J) are the fuel return, vapor and fuel supply lines, respectively.
The fuel pump is an in-tank design. The only differences being the TBI pump is a low pressure (15psi) compared to the tpi's 45psi. Also the TBI pump is a high volume vane type pump that operates at a very high rpm (3500-4000). the tpi pump is a roller vane pump. Also the TBI pump has a 3/8" outlet, while the TPI pump has a smaller 5/16" outlet.
Pump Lifespan: Always use the sock filter on the end of pump inlet as instructed by the manufacturer. Buy only high quality, American made brand name pumps (AC-Delco, NAPA). Use a high quality, name brand fuel. Change your in line fuel filter regularly (once a year is good insurance). Keep the electrical connections tight and water resistant, make sure the silicone "boot" is present on the connector to insure a tight seal. Keep the charging system in good working order, excessively high or low voltage is hard on a pump.
With this mind, the pump may last well over 100K miles, but even this is no guarantee. Remember this is an electrical component with moving parts.
If you are not using a internal pump system, like the factory set up, please read this article before starting.
I learned several things about using a external pump and the headaches I went through trying to solve my fuel cavitations and starvation problems.
Aftermarket fuel pump installation.
If you want to use your existing tank like a lot of street rodders would like to do and avoid the fuel delivery problems, visit Tanks. Inc, at their website http://www.tanksinc.com for a kit that allows you to install a internal pump system.
Above shows the Tanksinc fuel pump assembly already installed in my 1978 Camaro fuel tank.. The system is a Godsend as by installing a in-tank pump like the factory will avoid the possible external pump cavitation problems. Be sure to follow all the directions and precautions outlined in the instructions.
The late 1970's Camaro tanks has a vent line that is a a separate raised area on the tank. You will need to cut the line off as close to the tank as possible and then using a hole saw or snips cut a 4 1/2" hole through the tank and then the bottom of the vent reservoir. You'll then need to remove this assembly from inside the tank, it is a pain, but it needs to be remove or you'll wont be able to get the internal threaded split flange and pump assembly into the tank.
With some careful measurements, it is highly advisable to cut a access hole into the trunk floor to gain access to the fuel pump assembly just in case of any problems. I also cut it far enough back to get to the sending unit. On the sending unit, since it is not being used to feed fuel, cut off and crimp the fuel lines and seal them off with a gasoline resistant epoxy. I over kill cut to the left, but you can be just an inch or two from the fuel pump assembly and have enough room to remove pump. Cut the access before you install the tank.
After setting up the tank, I noticed I needed to rearrange the fuel lines. On the late 70's- to 1981, this is what works best to clear the trunk floor to keep lines from getting damaged. I also ty-wrapped them together to eliminate any movement. The lines shown here do not touch the trunk floor pan.
A piece of sheet metal of 28 gauge zinc plated steel will be sufficient to make an access cover. Use #6 by 1/4" long (from top of screw to bottom of thread) sheet metal screws to attached to trunk floor. The screws have to be very short to clear the tank as there is very little gap between the tank and floor. You will noticed in the picture at the top of the access cover, there are no screws because this is where the fuel lines are located.
Installation of the fuel filter which is required as soon as it leaves the pump, installation in the location between the tank and rear end makes access for changing very easy to do.
Another way is to use a aftermarket pump that you can mount underneath the vehicle in a area protected from damage. Follow the manufacturers recommendations in mounting as to allow the pump to operate efficiently. You'll still need a return line in your tank, however, no matter what route you choose.
Also, you will need to mount the pump at a level that is equal to or lower than the bottom of the tank, this will create a "siphon" that will prime the pump and keep the fuel flowing. Otherwise the pump will never prime and will be damaged from running dry.
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Courtesy of GM
Diagram above shows the typical layout of the stock GM TPI fuel system. Use as a guide for installation.
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