Fuel return line

[DblR]

Hello, finally figured this out. So here goes. I have a 72 Satellite Sebring plus. It has been changed. I've worked on it for 8 yrs. It's not original so go easy on me. I'm installing a fast EFI master kit w/inline pump. I'm close to being finished and I'm at the fuel line portion. Would like to use existing line but I'm concerned about return line. It seems smaller. Worried about the pressure with different size lines. It's stock not much hp don't need to much pressure. Any help? Thanks. DblR

 

[kiwigtx]

You will need to install a return line equivalent to the supply line size - typically -6AN .... or 5/16" minimum....... 3/8" would be better. The return pressure is probably quite low at around 4psi, but there could be significant flow....you need to make allowances for that otherwise there will be issues with pressure at the supply side.

 

[DblR]

Thanks for that. I was wondering about the different sizes. Kit came with 3/8 hose. But not enough to return it. Inlet at tank for return is also smaller. Out put looks 3/8

 

[kiwigtx]

Thanks for that. I was wondering about the different sizes. Kit came with 3/8 hose. But not enough to return it. Inlet at tank for return is also smaller. Out put looks 3/8

Standard return/vapour line in the B-Body cars is only 1/4" - which is far too small to be suitable for a return line.

 

[DblR]

I know, bummer. It's sounding like a sending unit replacement and bigger tube welded on for return.

 

[kiwigtx]

I know, bummer. It's sounding like a sending unit replacement and bigger tube welded on for return.

It might be worth checking out if replacement fuel tanks are available that have an in-tank pump c/w return line.

I just did a search and there's not much love out there for your model of car. Modifying the sender unit might be your easiest solution.

 

[DblR]

It might be worth checking out if replacement fuel tanks are available that have an in-tank pump c/w return line.

I just did a search and there's not much love out there for your model of car. Modifying the sender unit might be your easiest solution.

I'm hoping for a comeback on this model. Hated it in highschool but it grew on me over the years.

 

[Don67Satellite]

When I had EFI on my car previously, I was using a Walbro 392 inline pump. The PO had installed a crude return in the sending unit but it worked. Used 3/8" hose to feed the EFI, and the 5/16" hard line was used for the return. Again, it worked. YMMV.

 

[DblR]

When I had EFI on my car previously, I was using a Walbro 392 inline pump. The PO had installed a crude return in the sending unit but it worked. Used 3/8" hose to feed the EFI, and the 5/16" hard line was used for the return. Again, it worked. YMMV.

Not well versed on the EFI. I just wanted easy start ups and smother engine. I hope I didn't go to much. 3/8 in and out sounds alot. Pressure starts at 43 pounds.

 

[Don67Satellite]

No as @kiwigtx stated, equal size feed/return is ideal. I have heard good things about the FAST EFI, my friend uses one on his 340, he set it up, threw the handheld in the glove box and hasn't touched it in 5 years. Car runs great.

Myself, I didn't have as much luck with the EFI, but it wasn't a FAST. My 440 ran like garbage all the time. Went back to a manual fuel pump and a AVS2, and it starts up as easy as the EFI, runs smoother & pulls harder IMHO.

 

[DblR]

No as @kiwigtx stated, equal size feed/return is ideal. I have heard good things about the FAST EFI, my friend uses one on his 340, he set it up, threw the handheld in the glove box and hasn't touched it in 5 years. Car runs great.

Myself, I didn't have as much luck with the EFI, but it wasn't a FAST. My 440 ran like garbage all the time. Went back to a manual fuel pump and a AVS2, and it starts up as easy as the EFI, runs smoother & pulls harder IMHO.

I've decided to do the correct thing instead of the easy. I'll run new 3/8 line both ways. That way one day (ha ha) I'll throw more HP at it. This kit says up to 600.

 

[Don67Satellite]

Here is my old fuel sender. As stated previously, a very crude job by the PO, but it worked, and didn't leak.

 

[Purepony]

I'm hoping for a comeback on this model. Hated it in highschool but it grew on me over the years.

View attachment 1519191

View attachment 1519192

What are you talking about? That model already came back, have you looked at the prices? They used to sell for 15 to 20 all day long in pristine condition now they’re starting at 40-120 from what I’ve seen.

I’ve always liked that body style better than the earlier ones

 

[DblR]

I'm talking about the disdain of some of the square box 70 and later guys have for this model change. Some still hate it. They aren't as valuable as the squares.

 

[DblR]

Here is my old fuel sender. As stated previously, a very crude job by the PO, but it worked, and didn't leak.

View attachment 1519379

Looks like what I need. Is it correct that a line from that new nipple needs to go to bottom of tank? Something about gas bubbles from it spraying fuel from top?

 

[Don67Satellite]

Looks like what I need. Is it correct that a line from that new nipple needs to go to bottom of tank? Something about gas bubbles from it spraying fuel from top?

I have read that it would be ideal to have it do that, to not aerate the fuel, however how you see my old sender is how it was, and didn't seem to affect it getting fuel.

 

[DblR]

I have read that it would be ideal to have it do that, to not aerate the fuel, however how you see my old sender is how it was, and didn't seem to affect it getting fuel.

Am I on the right track about the HP? Do I need to have a bunch of pressure or can it run ok on less pressure? Not trying to set records just hope to finally do a burnout.

 

[Don67Satellite]

Am I on the right track about the HP? Do I need to have a bunch of pressure or can it run ok on less pressure? Not trying to set records just hope to finally do a burnout.

Your engine looks stock. If it ran good with a carb, it will likely run good, maybe better with the EFI.

Most EFI throttle bodies like around 56psi (if memory serves me correctly) so above that you need a regulator if it isn't internally regulated, but don't run below the recommended amount of fuel pressure.

Read the manual for these figures, and your return line routing.

If I understand your question correctly, you won't really be making more HP with EFI. The 600HP just means that the throttle body will be adequate for an engine + any mods, UP TO 600HP. Beyond that, they usually offer upgraded units with larger injectors etc..

 

[DblR]

Your engine looks stock. If it ran good with a carb, it will likely run good, maybe better with the EFI.

Most EFI throttle bodies like around 56psi (if memory serves me correctly) so above that you need a regulator if it isn't internally regulated, but don't run below the recommended amount of fuel pressure.

Read the manual for these figures, and your return line routing.

If I understand your question correctly, you won't really be making more HP with EFI. The 600HP just means that the throttle body will be adequate for an engine + any mods, UP TO 600HP. Beyond that, they usually offer upgraded units with larger injectors etc..

Engine is very stock. It does have headers. It's weak won't even turn tires over but that's not a huge deal. Just wanted to have it run smoothly and start up quick. I know about max HP on this kit. Wondering if not having huge hp that the difference between return line and input line will be a big deal. Read a few posts saying it works fine with different size lines and others that say no. My regulator is mounted above vapor return line and would be ideal to hook fuel return to that. Last resort is to run 3/8 lie provided from pump to carb and buy more 3/8 to return to tank. That will consist of replacing sending unit and tapping a new hole and welding a 3/8 nipple. I really didn't want to do that.

 

[Don67Satellite]

Doesn't have anything to do with the HP of the engine.

Whatever the fuel pressure psi that the throttle body manual wants is what you feed it and set the regulator to this. High pressure EFI hose from the tank to the carb should be SOP with running EFI. While you are under there may as well run a 2nd line for the return. Already spent the money on the kit, may as well do it right the first time.