EFI Anyone?

[RallySnake]

I drive my car a lot. I run TSD, Monte Carlo and touring rallies and have run events to Las Vegas, Santa Cruz, Austin, Texas and all over California. I have probably put 200,000 miles on my Arntz Cobra over the last 32 years and just spent 4 months rebuilding the engine. Again! This is the third rebuild on the the third engine. It's a '74 400 block. I don't want to do this again. Carburetors leak too much fuel in the engine during cold starts and that washes the oil off the cylinder bores and causes them to wear rapidly. EFI on modern cars has reduced engine wear so that they last much longer.

So I got a "Black Friday" deal on a Holley Sniper EFI system and have been gathering parts to complete the project. I bought a tanks.inc fuel pump system to fit the pump in the gas tank. I got an extra Walbro pump as a backup, a bunch of 3/8" brake line and the biggest EFI fuel filter I could find.

I have read everything I could find about the conversion on the internet and I have installed a mild Comp cam that makes plenty of vacuum and mid range power. The new Total Seal rings have seated nicely in the freshly honed cylinders and I have found and fixed all the oil leaks. I am about ready to start pulling the old parts off the car.

I plan to pull the old tank out first and have it cleaned and pressure tested. Then, start installing all the new stuff. I would guess that some of you have already done this and you may have gone through some learning experiences that you may like to share?

[joyridin']

I am not sure which tank you have in your Arntz, but mine did not have baffles of any type. It was a big open tank. After cleaning it out, I added 3 baffles in the tank. This was done with SS plate stock and numerous small holes drilled throughout. Also, I added a small section around the pump pick-up so when going through long curves, it would not run the pump dry. On the return, I built a can around the pump and directed the return to fill up this can. This allows the pump to always be submerged in the gas keeping it cool. I have a Walbro 450lph pump. I ran it through the filter, regulator, then to the engine. The regulator and filter are mounted in the trunk and the return line coming off the regulator is about 6" long. There is no return line traversing the length of the car. Mine is set at 60 psi per the EFI specs. There is no vacuum line, but I originally did install one using aluminum tubing from the engine to the regulator in the trunk.

For the O2 sensors, I added a square block between the header and sidepipe where they bolt together. Mine has 2 O2 sensors. In the block, I drilled and tapped each block for 2 sensors. This allows me to run an AFR monitor on one side, or both sides.

I have probably 4000 miles on this set-up and no problems so far.

Good luck!

[RallySnake]

You had to cut the tank in half to install the baffles?

[joyridin']

No. Mine has a large opening on top. There is a plate that mounts on that opening and the pump, fuel level sending unit, and fuel inlet are mounted on it. I cut the plates, fed them through that hole, and welded them in place.

[Luce]

What I did on the wife's c3 that worked great was kept the original (not factory, but...) mechanical fuel pump and added a surge tank where behind the drivers wheel well. Put a walbro under to feed efi, regulator return goes back to surge tank. Then the excess volume from the surge tank goes back to the tank via the old vent line. Without a float, the mechanical pump keeps fresh cool fuel in the surge tank, full to within 1/2 of top giving 1.5 gallons or so reserve if the mechanical sucks air. So I didn't have to mess with the original tank.

Also, there's a filter between mechanical pump and surge tank to keep debris from original tank out of the surge tank.

In my cobra, the surge tank is inside the main tank, kept full by venturi pump fed by return. Also has trap doors keeping fuel in middle section of tank. Never had any starvation.

Get it in and tuned and you'll love it.

[spdbrake]

If I eventually go to a in-tank pump for my FiTech EFI I will def add a Holley Hydramat to the pump Pick up.
https://www.holley.com/products/fuel_systems/hydramat/

[Tom Wells]

RalleySnake,

I have one of these feeding the 557 in my Mercury Zephyr station wagon: https://www.summitracing.com/parts/aei-18688

It is installed in the stock Mercury wagon tank following Aeromotive's instructions.

I run the car on the highway, in town, and also do track days at Daytona on the Rolex 24 Hour course with it. Highly recommended. Easy install as long as you have a tall enough tank, and can remove/replace the tank without too much hassle.

On the other hand, I have a drag racing type sump welded to the bottom of my Cobra's aluminum tank, about 4 or 5 inches deep and six inches or so square. It extends down at the rear of the bottom of the tank, so you can see it if you know to look for it. The pickup is under the sump, a fitting installed as a drain so to speak at the bottom of the sump; there are circular holes in baffles above the sump to further contain gasoline. I use an external Aeromotive A1000 pump located in front of the tank.

Both setups use 100 micron filters in front of the pumps, and 10 micron filters just before the injectors.

These obviously are not the only two ways of doing this job; they do seem to work. Each has run 10s of thousands of miles with only one A1000 pump failure. They each seem to work fine on the street and on the track.

Before I did the tank mod for the Cobra, it would run out of gas during a 75mph turn on the Interstate. Now it is fine!

Hope this is of some help,

Tom

[RallySnake]

You guys are a wealth of knowledge, thank you very much!

Joyridin', I would really like to see a diagram of your baffles. Since I read your reply, I have been studying tank baffles and have learned that there are wrong ways to do it. The blocks for O2 sensors sounds like a lot of work. But, putting the sensor out on the side pipe collector would not look good. I have been running an A/F gauge with an O2 sensor on the pipe for #3 cylinder and it gives pretty stable readings. Do you think that will be good enough for the Holley system?

Luce, How did you get a surge tank inside the main tank? The venturi pump is a second electric fuel pump? Please tell me more.

spdbrake, The Hydramat gets raves from off-roaders and it is my backup plan, too. It is just SO expensive!

Tom, I considered putting a sump in my tank. But, I have track rods for the suspension running under there. The Aeromotive system is beautiful, but twice the price of the tanks.inc PA-4 system. There is no way to add a second pump to that one. It is interesting that even the high dollar Aeromotive pump can fail. That's why I feel strongly about having a second pump. Last time it failed (when I had only 1 pump) was in East Los Angeles. Not a great neighborhood to be waiting for a tow truck!

[Cracker]

I had Fuel Safe build me a new cell this last Fall...I run a swirl pot but was a little concerned about the pick-up in the cell. I opted to have them install a Hydromat but later found out they can cause issues with overheating the pump. Now, I wish I hadn't added it - just a thought.

Cracker

[spdbrake]

Originally Posted by Cracker

I had Fuel Safe build me a new cell this last Fall...I run a swirl pot but was a little concerned about the pick-up in the cell. I opted to have them install a Hydromat but later found out they can cause issues with overheating the pump. Now, I wish I hadn't added it - just a thought.

Cracker

Thanks for the info Cracker. Can you link the pump heating issues you found please. I've spent a bit over an hour now on Google doing various searches and Nada thus far. Thanks.

[Texasdoc]

I tried a Holley Terminator system and it was a colossal failure. I went thru three WBO2 sensors at $120 each over a few months. Ended up needing a complete head rebuild. The whole ordeal is documented on this site. Don't know what the problem was - did the heads cause the holley to fail or did the Holley system cause damage the heads? Which was first, chicken or the egg?

I ripped it all out and went back to carb. YMMV (hopefully).

[Luce]

[quote=RallySnake;1436479]You guys are a wealth of knowledge, thank you very much!



Luce, How did you get a surge tank inside the main tank? The venturi pump is a second electric fuel pump? Please tell me more.




I made my own tank, 16 and 18ga 304 stainless, and it included a 1 gallon milk jug sized box, 1/2 open on the top.

I got the idea from my 88 ramcharger.

Where the return line comes back to the tank, it's pinched down to 1/16" nozzle. It provides 30 psi backpressure when the pump is running full speed (and the engine is using zero of the fuel) so it doesn't interfere with the regulator. Than nozzle is at the bottom of the tank, and it squirts into a 1" tube that enters the box. The velocity of the fuel out of the return drags gallons of fuel per minute into the box, keeping it full at all times.

Found a pic. I tested it in the swimming pool with an old fuel pump pumping pool water. You wouldn't believe how much fluid the nozzle drags in. I would say better than 1200 gal/hr. It could fill in under 3 seconds. The flat bottom sits and is welded into bottom of the mail tank. I also added a skirt around the cutout so it would suck the last 1/2" of fuel from the main tank.

[Luce]

Here's a view from the top. It took a little playing with the top baffle to get a shape that kept the pot full as possible. What comes in through the 1" tube washes op the wall (back of the car) and the top redirects it onto the pot.

[RallySnake]

That is f***ing brilliant!

[Luce]

I have to give credit to Dodge. I scratched my head for an hour when changing a fuel pump on my ramcharger in my poorer younger days. Why the hell did they do all of this? Then it hit me. This was my first EFI car repair.

The tank has 2 baffles with trap doors that try to keep the gas in the center compartment. The only place with room for the sender is the right compartment. If I have less than 3/8 of a tank, and swerve left and right a couple of times or take a long right sweeper, it'll read empty for 10-15 seconds until fuel seeps back to the right compartment.

Those picks were too big to attach.

This tank was my first TIG welding project. The first go was a fail. Had leaks and bad welds I could never get sealed. Second go I had learned to weld.

[Luce]

Another thing to make sure you're aware of. With a carb, if the fuel pump gets a bubble of air, it's through before you know it, and what's in the bowls barely flinches. If an EFI pump sucks up air, it has 43PSI of head pressure keeping it from getting fuel back into it's wheels. A little tiny 1/4 oz of air can cause a 10 second loss of fuel pressure, and zero fuel delivery as a consequence. This could be disastrous in a long sweeping maximum speed curve.

[RallySnake]

You have convinced me to build a tank. I will have to sharpen up my welding skills.

[spdbrake]

VS building a tank you maybe interested the FITech surge tanks. I'm using the fuel command center model fed by a Carter low press pump, but they have others. All are universal on application.
Fuel Systems – FiTech Fuel Injection

[Luce]

I have read lots of stories of heartache with those. The problem is they have a fuel float setup, and instead of returning excess fuel back to the main tank, it stops flow into the surge tank. At low speeds and load, the EFI return pump heats the fuel in the surge tank if to the point the EFI pump starts to cavitate and lose pressure.

I made something very similar on my wifes C3, but rather than stop fuel when it's full, it returns excess back to the main tank. This keeps the fuel in the surge tank from getting hot and causing the EFI pump to cavitate.

The surge tank is a good idea, but I'm not a big fan of the way the fuel commander tries to avoid having a return line.

[spdbrake]

Yes I have read the some folks having Command Center heating of fuel issues (which is returnless). The TSB from FiTech changes the duty cycle (aka pulse width modulation) from 90 to 40% which decreases the voltage to the pump to lower the the dead-head fuel pressure at low speed cruising or idle. Some folks are removing the rollover vent valve)which already runs back to the tank and essentially making it a return type system. I personally haven't seen those issues but then again I haven't been stuck in traffic yet in the summer plus I've done the TSB. I may need to mod mine if that occurs.

Granted the Command center would not be a good choice for you since you'd not have any control over the duty cycle with the Sniper.

The Hyperfuel G-Surge tank pumps are return style so no issues there.