Once again I would like to use this platform to give some input on a subject it seems folks are having problems with installing the new FiTech fi system in their coach. A “kit” like this needs to be of enough universal design to be able to work in many applications. In fact they need to make to be installed as simple or as complicated as someone feels they want to make it. And for those wanting this option to be really complicated to show their superiority over some mere mortal that can’t understand whay you did something….. I may be reading this wrong but there are so many different designs of the fuel delivery system on these FiTech kits, I figured I’d throw out my version, lets see if I can make it simpler.
OK, our fuel delivery system was designed by someone thinking of 2 tanks on a pickup truck…. kinda. We probably had another engineer in the fuel system project had the list of “fixed” parameters and the blended the 2 ideas together.
In that constant flow of fuel has to be for fuel injection so it won’t loose prime, a 2 tank system really isn’t the best idea. In that you have a return line to deal with that brings the not needed pressurized fuel back to the tank….. fuel gets hot under pressure, releasing this fuel back into the main tank will tend to heat up the fuel in that enclosure. Heat is already a problem with Ethanol laced fuel, we were forced to install a “fuel cooler” on the return line before it reached the tank to try and drop the fuel temp. Yet another “bandaide”. I hate all the bandaides we’ve been forced to put on the carb fuel delivery system and I sure don’t want to start doing this on these new systems.
So lets list the parameters that need to be considered in a fuel delivery system to this new FiTech fi system:
- There needs to be complete access to all fuel without using a fuel tank selector switch.
- There needs to be a return for the unused fuel
- There needs to be a cooling design for the returned fuel
- Being the highest failure rate component, the electric fuel filter needs to be easily accessible and easy to procure a replacement.
- Positive tank ventilation making up a sealed system is a component of all modern fi systems.
So why am I bringing it up here and not on the social network sites? I don’t want to be confused with arguing about someone elses idea and have a short word comparison. When I come up with something it’s ultimately important that it works as needed. My customers never stay nearby so everything I do needs to be serviceable by others and be the best possible way I can to do something. If ya wanna do it the way we do it…. here it is…
It needs to be simple to understand and EVERY consideration made. If anything fails I’m in the loop. It may not have been a fault of me doing something wrong still…. I am in the loop and I am the one always looked at to make it right. It could be a bad part… I must deal with it. Could be the roll of the dice or even an “act of GOD”…. I am still attached and I need to have a way out… Welcome to my world, the seat is hot I sit on so it’s more important than ever to me that I get things as right as I can! Hey, you have to have wide shoulders in this business but please remember…. “don’t shoot the messenger” at least I will be here to help, my phone is on 24/7 and I answer it! Hey, be nice I’m doing my best……
OK, so considering the FiTech fuel delivery system we do this:
Every fuel delivery system today must be sealed or as sealed as possible. We don’t put up with smelling fuel anymore. We’ve been spoiled with the completely sealed new computer controlled factory fi systems so the lines connecting the vacuum of the carb to the charcoal canister and twin tank venting system must be reused. Some say it’s not enough venting and I may agree but for now, we need to at the least retain the original positive tanks ventilation system fuel/vapor separator and all .
We have them new $89
Next, there needs to be a fuel return to the system that is a main component. This hot fuel needs to be processed (cooled down) before returning to the main fuel volume plus flow back with little retriction from the unit.
If we pump fuel out of our rear tank and back into the front one, the warmer return fuel can linger in the front 25 gallon tank, mingle with that fuel before being reintroduced to the rear main volume tank where the fuel is being taken from. The fuel will return in 2 ways from the front (accumulator /cooler tank We tie the 3 tanks together at the drain openings via a 3/8″ steel line… now I know, some pupu this idea having a fuel crossover line low on the frame. The forward suspension, motor and muffler system hang lower than this modification. This is a steel line, not a droopy rubber hose. If it bothers you, install a metal “skid plate” and this objection is over.
The 2 fuel tanks are already tied together via the fuel inlet hoses by them entering on the sides of the tanks. From 1/4 level up the 2 tanks have always acted as one, the crossover will only effect the last 1/4 of the system.
Doing this eliminates the A/B electric fuel solenoid that if original probably doesn’t work anyway! Having the return fuel go back to the system via the original front tank feed line means you do not have to drop the tanks to make any connection. I’ve found in a really good field test that the fuel filter socks in the tank do not restrict the fuel leaving or coming back into the system.
Hmmm, well maybe you SHOULD drop your tanks if you want to have a reliable fuel delivery system. Above is a bad design, aftermarket sender that has rusted apart from the Ethanol. You don’t want to put your beautiful FiTech fuel injection system connected to this piece of work! I just hooked mine up to see if we could leave the filter socks, you may wanna go ahead and drop yours. Hey good news on doing that, you only need 1 good sender in the rear tank. We’re only using 1 sender, the “fuel selector switch” on the dash will be bypassed. Connect both the light brown and light brown/white stripe wires to the original senders together. That way you can leave the switch in the dash alone and always look at the rear tank. The front sender only needs to be the fuel return so the electric part of it does not have to work. New senders are the price of the electric fuel pump the FiTech system uses … so buy an extra electric fuel pump and keep it in the coach. Good insurance because electric motors are 1 of the 2 highest failure rate components in electronics. Never leave home with an fi system without an extra fuel pump!
And speaking about this pump, we don’t use the special FiTech electric pump… we’ve sourced an off the shelf “Airtech” brand pump you can procure most anywhere. When the first pump dumps, install your extra and get a new extra! Trust me on this…..
Also thinking of that poor shlub that will have to replace that pump at the worst possible time, we mount the pump and a 12 microm in line fuel filter on the ouside of the frame where it’s easy to get to. Yeah, yeah I know…. “sure hope you’re not T-boned….” Me too but in that the FiTech computer shuts off power to the pump immediately upon turn off or any issue I feel for the sake of maintenance I’m putting the pump and filter there…. you want it inside fine,…… do that.
Now look at what we have now in this system….. we have contained venting, we have all fuel directly available to the electric fuel pump, we have a 25 gallon accumulator/cooler tank feeding the main 25 gallon feeder tank. We have ease of maintenance.
The “fuel commander” FiTech offers I feel is their attempt at standardizing fuel delivery to their system no matter what system the vehicle hases so yes, you could use their extra tank accumulator system and keep all that crap in our original system…. or you can adapt our unique system to do more. We have a very special 2 tank system…. lets use that uniqueness!
Now it goes without saying any fuel hose between the FiTech inlet and the electric fuel pump must be hi pressure fuel line and all the rest of the hoses must be rated 30R for Ethanol use. We install a standard steel fuel injection hi pressure 12 micron (standard) fuel filter before the pump just cause. The FiTech folks say their system only needs 30 micron filtration…. Wow, it means those injectors are spitting bolders! Think of the dreaded 5 micron filter in the snout of our beloved ole Q-jets Yuk!!!!!
There’s a good reason all motors today are fuel injected, the fuels today are formulated to work better in pressurized systems. Carbs. still work but any more funny business with our fuels (like E85 and worse) our carbs are not going to work! Welcome to our new world…..
I’m most interested in your thoughts on our fuel delivery system design. All I want is the best for our classic babies, I want them to work well, give me the fun it always had and not break down.
OK… any updates from your comments I’ll post below. This is the way we do things…. this is NOT the only way but it seems to work well for us.
It’s a new world out there brother, you need to get in it!
Today Savory brown exits the big house buffed out, seats installed, cleaned out and ready to meet the world…. I’ll do pics.
Thanks for dropping by we’ll see ya tomorrow…..