trying to figure out my itb parts

Belgian1979vette

Belgian1979vette

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Joined
Apr 4, 2008
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Koersel/Belgium
Just to ventilate a little bit.

I have my FI ITB intake, got the megasquirt ecu and all other necessary hardware and i'm getting ready to get the other parts, that is fuel pump, fuel pressure regulator, fittings, fuel lines,.... boy oh boy this is going to be a big order I have in front of me. Sorting out all of the fittings to use without having any possibility of comparing if I got them all right, right angle, size etc. what a nightmare.

Anyway to sort out the problem with a fuel sump with my 79 tank, i decided to make a round fuel tank that mounts in the engine compartment (small one :huh:) with 2 connections for the high pressure side of the efi system and 2 connections for the low pressure side coming from the tank. Need to sort out how i'm going to get it filled. Seems like I have to use a low pressure electric fuel pump for that, which ads more money to it.

Who said, that sometimes these things are better left as they are. Well...:lol:
 
You want my honest opinion?? after 13 years with TPI on my '72 here....

forget about the problem....if you corner agressively enough with less than 1/8 tank...it MAY die ...but driving normally it will not....

it's a NON ISSUE....

run a large filter in the line behind the fuel pump....
 
I really don't see why you are going through all that hassle. Buy a 82 pickup unit and an LT1 pump and you're golden. No need to buy super fancy stuff and buy who knows what kind of stuff.

You could also use on of those mech. Race Pumps piston pumps, they have the capacity to run FI.
 
Twin_Turbo said:
I really don't see why you are going through all that hassle. Buy a 82 pickup unit and an LT1 pump and you're golden. No need to buy super fancy stuff and buy who knows what kind of stuff.

You could also use on of those mech. Race Pumps piston pumps, they have the capacity to run FI.
Click to expand...

I havn't heard of a mechanical pump since the daze of VW injection, the old Bosch crap....but I was outta cars for about ten years there in the late 70-80's...

I would buy a simple pump for less than 100 bux at AZ or similar, they are generic allmost these daze...it's meant for mounting outside the tank, are about 1/5 inches in diameter metal case, white plastic on the input end and the output and electricals on the other end....the output goes to FI hose I use Erols rated at 250 psi and go from there, to a filter, then into the injection course mine is a '72, the '82 tanks did have baffles in there but I don't think the 78-81 tanks did....no need, still carb'd....I have thought of some extra crapassity for the tank in a baffle under there, auz tank, but from experiments I have done, the return hose needs be run to the top of the tank just as with the carb setup...what happens if done down lo at the pump is the pump starts making noise as if it was cavitating...engine seems fine though, but the pump is in a world of hurt, grinds like a mofo diesel or some such....

I have a complete TPI except tBody, if anyone is interested, cheeep.....

I even have extra sensors kicking around....

and a K/N oval/conical air filter for the intake on the Tbody...you can find stock tbodys around for cheep....unless it's a LT configuration or other hotrod item, 48mm flows well to 6000 rpm....supposedly....

I used the stock carb lines to feed and return...they fine in spite of who says what....IF the return was restricted any, the pressures would be high in the fuel rail, as that is what the reg is...just a vac controlled spring valve restricting the line....the pumps I describe are cabable of 60psi or so....plenty for our 45 psi systems....Hell, I have done 4500 rpm blasts twice with the thing at WOT running 150 mph, and plenty of beans left the way that mofo was pulling above that, I"m chicken....

come think of it, I even have a computer to run it with speed density...it's what is used for the K/N filter above.....1227730 I have several known good units....

you can go junkyard for the connectors....and I have wiring diagrams from '91 Fbody V8 to give you all the wiring you need.....I just spliced into the wires off the junkyard connectors....much easier than special tool kits to try working them plugs...they are a tiney little bitch to do anything with....

I vote the stock computer cause I tried doing the Mega Squirt thing, and found the old style Dport connector did severely limit the assess of information over the web, as I found NO computer that had any capacity to do both...no D port, but USB, or if USB, no D port....and then files wouldn't transferr for some damn reason....fuck it....fought it hard and furious for 2 weeks and tossed the towel....I think Bullshark bought it

IF I ever go to upgrade my computer which runs fine with the Alvin Anderson chip/calpac in it...I will go with a sequential system, and some program for a more modern computer....LS maybe....something I CAN definately controll with some program off my wife's laptop with USB connector and get hell over it allready....that or NO GO....

:smash::surrender:
 
Well Gene, I cannot use my original tank, because there is no baffling and it will suck air in. I will need to use something else. I cannot use a weld on sump, since the tank has a plastic liner in it.

As far as the ECU, I already have go a megasquirt (fully assembled) here and i tested it with an old laptop i bought for something like a 125$ that still has a serial port. Works like a charm (with the stimulator).

Anyway, i want a system that is completly safe for fuel (avoiding fire) so that is why i want to go the an-route.:beer:
 
Your pump will not suck in air unless you run the tank lower than 1/4 full. You can weld a cylindrical sump to the level sender/pump bracket to make sure the pump is always submerged in fuel.

You could also make a template off the fuel sender flange and fabricate a new flange with an ports, a picup w/ pump inside and trapdoors.
 
Belgian1979vette said:
Just to ventilate a little bit.

I have my FI ITB intake, got the megasquirt ecu and all other necessary hardware and i'm getting ready to get the other parts, that is fuel pump, fuel pressure regulator, fittings, fuel lines,.... boy oh boy this is going to be a big order I have in front of me. Sorting out all of the fittings to use without having any possibility of comparing if I got them all right, right angle, size etc. what a nightmare.

Anyway to sort out the problem with a fuel sump with my 79 tank, i decided to make a round fuel tank that mounts in the engine compartment (small one :huh:) with 2 connections for the high pressure side of the efi system and 2 connections for the low pressure side coming from the tank. Need to sort out how i'm going to get it filled. Seems like I have to use a low pressure electric fuel pump for that, which ads more money to it.

Who said, that sometimes these things are better left as they are. Well...:lol:
Click to expand...


So to recap, you are talking about running a low pressure pump from the tank to an underhood accumulator (sump) with a high pressure pump to the fuel rail. Unused fuel is pumped back into the sump and the sump would have a return line to the tank?

Seems like a complicated system. You will also be pressurizing your return line with fuel from the low pressure pump.
 
And that pressurized return throws off the pressure regulator as the pressure drop is not the same anymore, requiring you to change that also.
 
Why would there be a pressure drop ? I would think it would have the same pressure drop as a return line connected to the tank. The regulator only opens when a specified pressure is reached and the high pressure fuel will end up in the sump, which pressure is lower and open to the tank side. However I'm not sure though. I got the idea from a guy over at CF that posted a link. In that link they used a plastic sump, which I don't like at all.

TT, I'm not exactly understanding what you are trying to discribe.
 
Something like this, this is out of a modern european car, a contained fuel pump:

d585_3.jpg
 
Yes, but even with the fuel sloshing back and forth the pump will always have a semi steady volume of fuel around it, you won't run the pump dry due to fuel sloshing.
 
Belgian1979vette said:
Why would there be a pressure drop ? I would think it would have the same pressure drop as a return line connected to the tank. The regulator only opens when a specified pressure is reached and the high pressure fuel will end up in the sump, which pressure is lower and open to the tank side. However I'm not sure though. I got the idea from a guy over at CF that posted a link. In that link they used a plastic sump, which I don't like at all.
Click to expand...

The fuel rail regulator is always basically "open". It is returning fuel into your sump at whatever flow rate the regulator will deliver and still maintain ~43 psi. At the same time you have your low pressure pump supplying fuel to your sump at say 8 psi. Your sump will fill with fuel.

The configuration you describe is the same that EFI boats use (only because the tank is usually lower than the pump) however, they use a float valve in the sump to isolate the high pressure circuit from the low pressure
 
TT,

Ok, let's say that fuel sloshing around won't be a problem, but what when the fuel level gets below 1/4 ?

BB,

I more or less think i see what you want to say. You mean that the amount of fuel ending up in the sump would be to much to return via the 1 return line. Maye a second (high pressure line) could solve it. But then again, it would get complicated.
 
Belgian1979vette said:
TT,

Ok, let's say that fuel sloshing around won't be a problem, but what when the fuel level gets below 1/4 ?
Click to expand...


The 2 are related, the fuel sloshing is why it's possible for the pump to suck in air, the fuel sloshing around can leave the pump dry. With a setup like above that won't be an issue, the fuel in the container will be at about the same constant level, even with fuel sloshing around in the rest of the tank.
 
I checked out the racepump (piston type) also. They seem not to be working with a return line. The drawback however is that it makes it possible for the pump to put air in the system when it sucks air through the tank.
 
That's because the return is not on the pump, it's on the external regulator. Your fuel system will have a diaphragm type return style regulator, excess pressure is bled off back to the tank. The regulator is situated after the last injector on your fuel rail or close by, this pressurizes the entire system between pump and regulator.
 
If you plumb the return into the accumulator tank like you described it will most definitely not work because of the perssure differential Larry pointed out. If you plumb the return straight to the tank, then it will work and it will be exactly what I described above, a surge tank. Like used on old mech FI systems, those simply use a set of holley float bowls to regulate fuel level in the accumulator tank.
 
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