Modifying stock fuel lines?

MNwe4

Member
Joined
Sep 29, 2008
Can anyone clue me in or point me to a thread that shows what can be done to the stock lines to have the best shot at running a DW or TT340 pump and 80lb injectors without having too much of a restriction? The TT340, injectors, and chip are on their way and I've been searching for days, but only found tidbits of info. So far I know that on the feed side of the hanger in the tank a section can be cut off where it necks down and that should help increase flow to the motor. I've also read of people enlarging the line at the saginaw fittings of the return line with a drill bit, but don't know at which locations and what size bit to use. Is it also worth replacing the rubber sections of the line due to their age and the coversion to E85? I'm sticking with the stock fuel rail and billet style regulator also. Thanks.
 
There are MANY GN's using a DW pump with completely stock fuel lines.

I have personally installed 1/2 dozen, and know over twice as many DW pumps others have installed with no issue. :)
 
X2 2 of my buddies installed DWs with stock lines and both did not have any issues
 
Can anyone clue me in or point me to a thread that shows what can be done to the stock lines to have the best shot at running a DW or TT340 pump and 80lb injectors without having too much of a restriction? The TT340, injectors, and chip are on their way and I've been searching for days, but only found tidbits of info. So far I know that on the feed side of the hanger in the tank a section can be cut off where it necks down and that should help increase flow to the motor. I've also read of people enlarging the line at the saginaw fittings of the return line with a drill bit, but don't know at which locations and what size bit to use. Is it also worth replacing the rubber sections of the line due to their age and the coversion to E85? I'm sticking with the stock fuel rail and billet style regulator also. Thanks.

The idle fuel pressure problem is a possibility when using gasoline. Since you're using E85,you should be fine.
 
Well those are some encouraging comments. So do you all think I should just not mess with anything, hook it up, and see what happens? The motor and trans are out of the car right now, but not for long, so if any mods are needed I'd like to do them now.
 
The problem with the stock feed line is it limits the potential flow. You won't hurt your engine if the return line isn't big enough. drill all the Saginaw fittings and the sender tubing out to about .280". Voltage will help more than anything.
 
Well those are some encouraging comments. So do you all think I should just not mess with anything, hook it up, and see what happens? The motor and trans are out of the car right now, but not for long, so if any mods are needed I'd like to do them now.

Normally I would say monitor fuel pressure to see if it keeps up with boost. If it doesn't,then do something. Since your motor is out I would drill out the four Saginaw fittings in the supply line. I drilled mine to .299".
 
Thanks guys, good points. Forgot to mention that I'll also be using the boost-a-pump I already owned. I have always had an electronic sender and fuel pressure gauge, but now it will also be hooked up to the powerlogger so I can look at FP more in depth. Noticed that one of the rubber sections was labeled fluoroelastomer, which is Viton and should be decent with E85. Is this the case with all the other rubber line sections and o-rings in the stock system?
 
I had the DW pump with stock lines in my car....its the pump I went 10.57 on but that was on gas...With the stock lines and no line mods it would only support my build to 18psi on E-85...any more and then inj d/c hits 100%
Jaysen has the pump now and will be running it at BIR in a week!
Your turbo size compared to mine will help you guesstimate how much or little boost it should support on corn
-Dan
 
northerngn said:
Your turbo size compared to mine will help you guesstimate how much or little boost it should support on corn
-Dan

I doubt either of you were/are close to being out of turbo. The engines mass efficiency will determine the fuel consumption. Not the turbo. Whether it happens at 26psi or 17psi if the mph is similar then the mass flow is similar.
 
I doubt either of you were/are close to being out of turbo. The engines mass efficiency will determine the fuel consumption. Not the turbo. Whether it happens at 26psi or 17psi if the mph is similar then the mass flow is similar.
That's not what I meant... I mean that if his turbo is bigger than mine then he will run out of fuel system even sooner at boost or just turn ut way the F down (which sucks)
Before I went to a cell and big lines and pump I could run 26 psi at 80% d/c on gas
Switch to E-85 and I have to back it down to 18 just to keep the d/c less than 100%

-Dan
 
Then,you weren't out of pump. You were out of injector.

Riddle me this my friend;) Why after I did this

http://turbobuick.com/forums/threads/my-e-85-fuel-system.382212/

My 83's now support the identical everything on E-85 but now at more boost:confused:


I was not out of injector, (so to speak) I mean, I do need bigger injectors but the whole adding bigger injectors to a small pump and tiny ass lines didn't make as much sense as going bigger and letting those 83's stretch their legs a little more

But I do have to openly admit this motor wants 120's...Then I can go higher on the boost as now supply WILL NOT be an issue but I have a feeling she will still be faster at 22-23 lbs on corn than it was at 25-26lbs on gas

-Dan
 
I'm one of the few who HAVE to run a new return line due to my return line being restricted. I drilled out the return Saginaw return and I thought I fixed it...I didn't. Just ordered a braided -6 AN Teflon line and fittings for a completely new, larger return. We'll see what happens.
 
Can't believe I forgot to ask this earlier, but Bison and Ttype6 both mention drilling out the supply line, but how about the return line? In the engine bay on the driver's side the return line is 1/4" OD. The actual ID at the sag fitting looks extremely small here. Are people drilling those out and to what size so that the o-ring still seats properly?
 
Normally I would say monitor fuel pressure to see if it keeps up with boost. If it doesn't,then do something. Since your motor is out I would drill out the four Saginaw fittings in the supply line. I drilled mine to .299".

Would anyone mind pointing a picture out that would explain the location of these fittings that need to be enlarged?
 
...If you can't you'll need to drill the two Saginaw fittings to a larger diameter on the return line. One is located where the return line connects to the regulator. The other one is located where the return line connects to the steel line where the line sticks out of the frame by the steering box.

From another thread I was reading regarding Turbo Tweak's fuel pump.

http://turbobuick.com/forums/threads/return-line.382897/
 
The one at the regulator is a bit larger than the one at the frame, isn't it?

Another thought, I know the idea is to adjust to 43 psi line off, but doesn't it actually need to be able to regulate down to say 37-38 somewhere since that's where it will go once the vac line is put back on? I understand it would be fine when in boost, but under normal street conditions the system is in vacuum most of the time. Maybe I'm confusing myself, time to head home.
 
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