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Wed Nov 25, 2015 10:46 am

Hey guys, I've got a question about my EFI setup. Do I need, or should I incorporate a way to bleed the air out of the lines? I'm familiar with fuèl injection, but I've never installed a system that I've made from scratch. I'm getting fuel pressure, no leaks but a ton of gurgling and squeeking noises coming from only the regulator. I changed the spin on filter and allowed the tank to drain out of it all the way to the pump inlet. Then I connected to the pump. Do I just run the engine until air goes away?

The regulator is the highest point in the system, but sounds like a whoopie cushion every 10 seconds or so.

I have the return line routed back to the fuel inlet instead of dumping into the top of the tank.

The gauge bounces around when I hear the gurgling but mostly stays around 40 psi.

Wed Nov 25, 2015 11:22 am

"I have the return line routed back to the fuel inlet instead of dumping into the top of the tank. "

So the air just runs around.

Look at swirl pots and running a low pressure loop throuh the pot
or simply dup the hot aerated fuel back into the tank.
Otherwise your burps and squeaks may end up with boiled fuel instead and no FI until it all cools down.

The choice of how to return fuel to the tank is one thing stalling my FI project.

Wed Nov 25, 2015 11:58 am

The injectors should run a priming pulse when you turn the ignition on. This should purge any small amounts of air out. If its a new motor, you might just need to turn it off and on a few times.

Wed Nov 25, 2015 12:26 pm

fastfil wrote: The injectors should run a priming pulse when you turn the ignition on. This should purge any small amounts of air out. If its a new motor, you might just need to turn it off and on a few times.

Yes, new everything. I don't have an ECU to connect to the injectors yet. I've just been putting power to the pump in short cycles so far.

Wed Nov 25, 2015 12:32 pm

mikedjames wrote: "I have the return line routed back to the fuel inlet instead of dumping into the top of the tank. "

So the air just runs around. This.

Wed Nov 25, 2015 12:50 pm

i ran it like you did. no problems. it will go away once you purge out the air the first time.nothing wrong with running a tee instead of returning to tank.

Wed Nov 25, 2015 1:24 pm

There is a reason all manufacturers run an extra hose back to the tank.
I will likely work most of the time anyway, but not well enough to sell new cars.

Wed Nov 25, 2015 1:46 pm

I had a system like that, burned up 2 pumps. There is a reason factory efi systems return in the top of the tank

Wed Nov 25, 2015 1:46 pm

and there are also new cars that dont return at all. i guess they are wrong too. alot of people including myself have run it this way without problems. if it idles ok than it should be fine becouse thats when you get the most return. the more rpm the less return.

Wed Nov 25, 2015 1:56 pm

So, some undiscosed manufacturer runs without return. This is interesting, I would like to know more about this.
The rest of us should clearly do it as well, because those who burned pumps and suffered from hard starting with warm engines simply dont know what they are doing.

Wed Nov 25, 2015 2:05 pm

You're probably familiar with "return-type" fuel injection systems, but have you worked on a "returnless" system?

Returnless systems are found on many late model cars and trucks. The first ones appeared back in 1993 on certain Chrysler V6 and V8 truck engines. By 1998, all Chrysler cars and light trucks had them. In 1996, Toyota introduced its first returnless system, followed by General Motors and Ford in 1999. Honda went "returnless" in 2001, and today you'll find returnless fuel injection systems on almost all new vehicles.

http://www.aa1car.com/library/returnless_efi.htm

Wed Nov 25, 2015 2:21 pm

I read through the link you provided. Interesting stuff. But as expected, those systems serve the purpose to solve a problem few of us are concerned about - namely emission control.
In order to make this work they have to raise fuel pressure to avoid vapor buildup in the lines.
I have never worked on newer tech like this, and still fail to see any relevance to us.

Wed Nov 25, 2015 2:26 pm

So you just want to argue. well my dad can kick your dads ass!!!
next up religion!! :P

Wed Nov 25, 2015 2:36 pm

No, advocating returnless fuel injection with older tech pumps and regulators is bad advice. The fact that more modern systems use this with completely different hardware is no reason for us to do it.
Experimenting should be encouraged, but this forum supply advice to people who need help on their builds.
Saying that a return is not necessary without also saying that you need a special pump/regulator/software is not nice.

Wed Nov 25, 2015 2:40 pm

ok ok you caught me i was advocating returneless fuel injection. dang nothing gets by you.

Wed Nov 25, 2015 2:41 pm

before you reply. you win! everything you say should be followed to a tee...

Wed Nov 25, 2015 2:48 pm

Very clever conclusion. It has nothing to do with the discussion, but hey - we can't have everything.

Wed Nov 25, 2015 3:14 pm

there is more than one way to skin a cat. why you would want to skin a cat is beyond me! i prefer woking the dog..... :lol:

Wed Nov 25, 2015 4:12 pm

Hey now.... :)

I tried to research the pros/cons of the different returns before I set it up. The main reason I did it this way was the single cab tank placement. It was also easier to plumb into the existing tank drain. I'm using a fuel cell with no baffling so it seemed this method would keep air out of the drain while fuel sloshes around.

I've read that some guys feel the return in the top of the tank aerates the fuel? I tried to keep the lines away from heat and even made the rails out of steel to lessen the impact of heat soak. You can see I even used a Y fitting instead of a regular tee since some guys said the CB system's tee was no good... Hmmmmm...I went overkill on the tubing and hose sizes and used AN to keep flow restriction to a minimum. The pump volume is also ridiculous for my hp level, but that's how I roll. Overkilling the hell out of everything I build lately. :wink: carry on

Wed Nov 25, 2015 10:46 pm

I have almost 12,000 miles on my FI turbo with a fuel tank tee.

I have not had any issue with fuel.......except I am now at 94% duty cycle on my 32# injectors at 22 lbs boost........ :cry: :cry: