View Full Version : My New Fuel System

01-02-2003, 05:15 PM
Well I redid my fuel system over the past 3 days thinking it would help my fuel starvation problem. It made it a little bettter but didn't cure it. I'd think 200 needles would let enough fuel in, but it seems they don't unless what did can't supply enough fuel for the motor (I doubt that). Looks like I need to invest in some 300s.

Any way on to the fun part. This is all done on my 2g but it'll be similar for a carbed 3g except that the 3g has its pump in the tank. You 3gezers also luck out not haveing to pull the tank down to get the pickup out, though you might want to take the tank down to make it easier to run new lines. Now find a lap to sit in cause its story time.

This is the old 2g pickup, The 3g part looks nothing like this.

Then I bent up a piece of 3/8" steel tubeing to sort of resemble the original tube.

If you're wondering why go to all this trouble, here's the diference in the pipes.

Then cut the old tube off and drilled the hole out to fit the new tubing, got out my welder and did a really bad job of welding the new tube on. I managed to set the connector for the fuel gague on fire 2 times as well.

I had to trim it up a little bit to get it into the tank. I also tossed a coat of paint on the top (don't paint the part that goes into the tank). Once it was all dry I put the tank back together and bolted it back up.

With the tank in place I tossed the old 2g prelude pump I was useing, and replaced it with this nice holley red. (The stock pump was on the frame rail next to the tank. This one is on the spare tire well, it was too big to ever fit where the stock one was. Stock 3g pumps are in the tank.)

Next I ran some 3/8" soft tubing up to the motor. Soft tubing is so much easier to work with but takes twice the room of hard lines. That was boreing so I didn't take any pictures.

Then I mounted the holley regualtor that sean (formerly known as funstick) had given me when he helped me with my trans. Spliced in my fuel gague and fired up the pump.

Once I got the regualtor figrured out, didn't have the spring in right after cleaning it, the pressure stayed at a steady 4psi. It held 4psi when the motor was running and when it was floored. Thats alot better then the old pump which was at 2.5psi (2-3psi is spec for the pump), but fell to 2psi when the motor was running at 2000 rpm and fell to barely 1psi as soon as it was floored. I can now get about 1/2 way though 2nd gear, depening on how much I let the tires spin when I shift, before it runs out of fuel which is a little better then running out of fuel just as I shift as it was before.


01-02-2003, 05:29 PM
Wow, do you suggest that I would invest in a better fuel pump? It doesn't look too difficult to do. What gains do you think you got?

01-02-2003, 05:48 PM
Its not easy, getting the old lines and the tank out are both real pains in the ass. I spen't the better part of 3 days on this. I you don't need one with a dgv, I didn't even need one with the 40 DCOEs (I was problaby right at the limit, but I never checked). I seem to need it now with the 45s though. There is no performance to be gained by just the pump. Its needed to support other mods, like big carbs and a cam, that let alot more air/fuel into the motor.


01-02-2003, 05:50 PM
Ok thanks for clearing that up for me. :bow: PhydeauX :bow:

01-02-2003, 06:57 PM
cool... could you use an efi pump with that pressure regulator and run the returnline?

01-02-2003, 07:35 PM
I don't know if it'll hold back that much pressure. The pump puts out 7 and it holds it back to 4 no problem. I'm pretty sure it'll hold back a blue pump to, puts out 15 psi or so. But I'd really doubt it could hold back 50psi.


01-02-2003, 09:22 PM
Well, Jan 15th is the day I send out my $850 for my set of brand new 45's and manifold. So, I'm thinking I'll be knocking on the door labelled PhydeauX in just a few months time! Thanks for the post on that. Do you think that with my 45's I'll have to mess with the fuel system? I'm not positive on the jets yet, but I know that the chokes are 36's if that help determine the fuel answer at all.

PS.. What jets/chokes are you running with on those 45's? Any estimate on hp/torque gains from stock with those nasty carbs? I know you got a cam too, I'm talking from dead stock to now, what sort of gains?

01-02-2003, 11:13 PM
The car never was dead stock, at least not in my hands. I bought it with a blown motor and trans so its had the cam and a20 motor swaped in from the beginning. I still don't know how fast it is with these carbs, I still can't get more then half way though second before its starving for fuel. It definitly pulls, and it pulls hard. As for performance gains, when I first built it it had the same cam, a stock a20a1 manifold on an a20a3 motor, and a DGV down draft carb. It was running 16.7s @ 82, when I changed to the 40 DCOEs it ran a 15.9 @ 86. Its yet to be run with the 45s. My butt tells me that it feels faster, but I have also been doing alot of driving in my TDI which isn't very well endowed in the horse power department. I'm useing 36mm chokes, off hand I forget what the jets are. I haven't done anything as far as tuning them anyway because I can't get enough fuel in them for some flat out tests. Though even partial throttle acceleration is rather impressive. I can't tell you if you'll need to do something like this or not. If you still have a stock cam then you problaby won't have to. It wont be reving high enough to pull enough air in to need as much fuel.


01-02-2003, 11:27 PM
here is part of mine..


01-03-2003, 02:20 AM
so you painted the entire pickup and return assembly, what kind of paint did you use?

01-03-2003, 03:33 AM
Probably a real stupid Question But, Did you increase the lines going from the tank to the engine compartment?

01-03-2003, 04:14 AM
Next I ran some 3/8" soft tubing up to the motor. Soft tubing is so much easier to work with but takes twice the room of hard lines. That was boreing so I didn't take any pictures.

01-06-2003, 03:05 PM
Sean gave me a little lecture on using soft tubing for the entire run the other day. There was something about my safety and then the part that finally convinced me. Most race tracks, especialy the ones that put some care into their tech inspections, won't let you run if you do something silly like that. So I pulled the hose out, it was run in the cabin which makes it even worse, and replaced it with some aluminum fuel line. I had a spring bender this time and that made it a hell of alot easier then when I did my corolla. The reason I didn't use the hard line in the first place was because I had such a bitch of a time running it in that corolla. I did take some pics, but they arn't very interesting so I'm not going to bother to upload them.

I'm just posting this incase someone decides to follow in my foot steps and do it the wrong way.

Justin you make my pics look so small. I didn't paint the underside of my pickup because I was worried about the fuel disolving the paint. I wasn't going to be bothered with looking up to see if that would be true or not. By the way, I've always been under the impression that the return line should be the same size as the feed line in a high volume system. I've been told that this is done keep any restriction in the return line from causing a higher fuel pressure at idle and low load conditions when most of the fuel is just being pumped back to the tank.


01-06-2003, 09:01 PM
Well the whole set-up is for a supercharged mustang in which I modified it to fit my car. As far as I know, that is what I thought about the return line, but most say it does not matter, the positive is -10an and the return is -4an, which I though was too small, but it is a kit that aeromotive puts out stating is can support 1,000 hp.

01-06-2003, 09:48 PM
Jeez.. thats a -10, I thought it looked pretty big. I thought the -8s (send and return) that I used on my corolla were overkill. -4 seems kinda small, that works out to somehting like 5/16" doesn't it.


01-14-2003, 11:16 PM
Would changing the fuel line configuration effect the carbs at all.
I mean like having the fuel line split into a "Y" and then go to the carbs instead of one carb is in front of the other. And have a pressure regulator on each line to the carb and not before the split.

01-14-2003, 11:36 PM
At the top of the pic I put what I though would be a good idea.
Below I put my concerns about hooking things up in a series...
like how one LED will be slightly dimmer then the LED that came first in the circuit.