EFI Install: Fun With Fuel Lines!

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I crawled under the 1972 Pontiac LeMans for the 50th or 500th time of the weekend. I laid on my back on the Craftsman creeper, the Ford nine inch rear end inches above my head. My daughter crouched in the trunk directly above me, tightening a button-head bolt with an allen wrench so we could mount the fuel pressure regulator/filter. I kept the nuts from spinning underneath the car. Then our fifteen year old daughter exclaimed “It’s tight”, referring to the last bolt. I rolled from underneath the car and replied “Thanks for your help. I think I’m done for the day.”

This all went down when I decided to install the Holley Sniper EFI unit into the Pontiac. Installing the throttle body in place of the carburetor took twenty or so minutes. Wiring took all of an hour. I spent most of that time determining optimum routing of the wires. I drilled the exhaust and installed the oxygen sensor, removed the mechanical fuel pump and replaced it with a fuel pump delete plate. To compliment the fuel injection, I purchased an EFI fuel tank from Holley, with their in-tank fuel pump and a new sending unit. Preparing and installing these two items was straight-forward thanks to the clear instructions provided in the kit.

Fuel level sending unit. Basically, a ping pong ball on a stick.
Sending unit on left and fuel pump, on right, both installed in the new tank.

Then… then it came time to make a path for the fuel from the tank to the engine, like a pioneer venturing out on the Oregon Trail (ideally without the whole dysentary thing). Holley’s documentation indicates I need at least a 3/8 inch supply line and a 5/16 return line. The throttle body regulates the pressure to about 60 psi. Any extra fuel is returned to the tank via the “return line”. My Pontiac had supply and return lines. Neither were of adequate diameter to supply the Holley throttle body. Thanks, Pontiac. Way to go guys.

You might think one would just buy fuel lines of adequate size to feed the new throttle body. That would be ideal, but the process to install fuel lines in the factory location requires one to lift the body from the frame. I know myself. I know if I lift the body from the frame, I will realize how “easy” it would be to purchase a tubular frame chassis for ten grand from Art Morrison and spend the next ten years installing it under the body I just lifted. This would not do, as I’d like this car back on the road while I am still young enough to enjoy it. I really only had one choice… I would have to bend my own fuel lines.

Sometimes working on the fuel system requires snacks. And wine.

The process of creating fuel lines is tedious. Meaure, bend, test fit, bend again, test fit, bend again, measure, make the next bend… it goes on and on. Once the line is bent, one must make sure that the fittings are slid on the tubing before the flaring process takes place (otherwise there is no way to install these fittings). My method involved bending standard steel fuel line the length of the car and then test fitting it on the car. I used this line as a template for bending the stainless steel line that would be the final product. In addition to the steel line, I used Holley’s Earl’s Vapor Guard hose. This hose is compatible with modern fuels, is very durable, easy to bend and can withstand pressure up to 220 psi. AN fittings from Earl’s were used on the lines.

Stainless lines routed into throttle body. Earl’s gauge verifies adequate fuel pressure.

While fabricating the supply line, I realized how long this would take, since a return line was needed and I would have to go through the process twice, essentially. Midway through, though, I discovered that Holley makes a filter/regulator that can be mounted near the fuel tank (link here). This piece has a return port in it, which reduced the required length of the return line from fourteen feet to eighteen inches. I purchased it, and a plug for the return port on the throttle body and saved about three full days of work. Our daughter climbed in the trunk to help mount the filter and our day was done. Things were looking up.

Once the fuel line had been routed and secured, I plugged in Holley’s handheld little computer doo-hickey, put in some settings (such as number of cylinders, type of cam, idle speed, etc.), disconnected the fuel line from the throttle body and attached a hose to it, which I routed to a fuel container. I was pretty careful cleaning lines before I attached them to the car, but I wanted to run some fuel through the entire system to flush out any remaining debris that could clog the fuel injection system. I got in the car, turned the key to run, and heard the electric fuel pump in the tank buzz to life. A second later, fuel was flowing into the jug. One more minor victory!

Once flushed clean, I connected the fuel line to the throttle body and proceeded to re-check my wiring work. Everything looked right, so I readied my fire extinguisher (safety first) and turned the engine over. It cranked, but failed to come to life. Looking at Holley’s handheld computer thingy (sorry to get so technical), I saw that it wasn’t recognizing the signal from the distributor. I checked the wiring again, and realized that two of wires were switched, likely because they were the same color. I think they were the same color, any way. I’m a bit color blind, so one could be green and one yellow, for all I know. I got back in the car, watching the handheld device for the tachometer to change from “Stall” to an actual RPM reading. I turned the key and before I could note an RPM, the car started! I let it idle, as the ECU went in to learning mode, its artificial intelligence becoming conscious that it was connected to a 400 cubic in Pontiac engine.

I reigned in my excitement, exited the car, got on my hands and knees with a flashlight looking for fuel leaks, but there were none. A check of the fuel pressure gauge revealed that the system produced the appropriate 60 psi. Even the fuel level looked to be about right. With all systems checking out ok, I let the engine come up to temperature.

The engine temperature settled in at 195° F, which is typical of the LeMans at idle on a warm day. Idle was at 1100 RPM. The instructions stated that when the coolant temperature reached over 180°, I should adjust the idle to where I like it (750 RPM) and then shut the car off and restart it. With these steps completed, the 400 cubic inch engine idled as smoothly as a 400 cubic inch American V8 of this vintage can. One issue I had with the carburetor is that the idle would sometimes drop too low when the air conditioning engaged. I cranked up the a/c in the car and the efi unit compensated for the extra drag on the engine without fear of stalling.

Pontiac 400 at idle with new Sniper EFI.

The test drive has not yet happened, but that will be the next chapter. I am installing new parking brake cables in the LeMans, which I should be able to complete in an afternooon. Unfortunately I haven’t had an afternoon as I’ve been busy preparing the 1985 Toyota Celica GT-S for a 24 Hours of LeMons race at Thunderhill. Yes, NachoFriend Racing will battle the 5-mile track. Read all about that soon at needmorecars.com.

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