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Discussion Starter #1
Just finished hooking up the fuel cell, and it idles like crap. What's the minimum EFI return line for a TPI 350? I'm running -4AN, and I'm thinking it's too small. I don't have an inline pressure gauge handy, but that seems like the most problem/solution.

:confused:

Anyone run a -4AN return on a V8?
 

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too small, I would run 5/16 or 3/8.

Try just running some larger line, dumping in to a 5 gallon can, just to see if thats the problem. (alot easier than completely re-working the return line to find out that wasnt the problem)
 

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Discussion Starter #3
bgreen said:
too small, I would run 5/16 or 3/8.

Try just running some larger line, dumping in to a 5 gallon can, just to see if thats the problem. (alot easier than completely re-working the return line to find out that wasnt the problem)
I thought about that after I cleaned up, it's 5/16" to the bulkhead fitting, then it's -4AN so it'll be easy to just disco and put into a can. I'll try this tomorrow.

It ran fine before the cell, if this doesn't work I'm guessing it's not getting the FP it needs...(but I think it's the return line)

:beer:
 

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I use a 8 feed, and a 8 return. Really cant be too big for the return, but a 6 should be minimum.
What pump are you using? The one I have was available at Autozone. Running about 40psi.
 

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indysand said:
I use a 8 feed, and a 8 return. Really cant be too big for the return, but a 6 should be minimum.
What pump are you using? The one I have was available at Autozone. Running about 40psi.
TPI should run at least 45 psi at the rail. Will perform better with about 47/48 at the rail. This is checked with the motor running and the vacuum hose disconnected from the rail. Only the 85 TPI used less fuel pressure at 39 psi.

The 4AN is too small. The adapters from Accel that you purchase are 6AN. Are you saying what's happening is that it can't return fast enough and is reducing the pressure on the feed side? Please post the solution.
 

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Discussion Starter #6
MrWillys said:
The 4AN is too small. The adapters from Accel that you purchase are 6AN. Are you saying what's happening is that it can't return fast enough and is reducing the pressure on the feed side? Please post the solution.
My pressure gauge is busted. :rolleyes: I haven't used it in awhile, and the feed hose is all fubar'd.

Anyway, the high return line pressure would increase fuel rail pressure and run too richly.
 

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If you need fuel cell parts in Northern NJ.. Daves Speed shop in Harrison has all the goodies in stock. Your return line is the problem.

Good Luck,

RK
 

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Discussion Starter #9
chris demartini said:
Ox, I am going to be hooking up my fuel cell soon. I have the same engine as you, what size AN did you use for the supply?
I used the -8AN to the fuel pump, then 3/8" line from there (My original 3/8" line). The return is 5/16" up to the bulkhead fitting, then I used a prefab line to the tank.

I used the Walbro 255 with the custom fittings from http://www.fuel-pumps.net/
 

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Discussion Starter #11
chris demartini said:
Can I slip -8 over a ford fuel pump I have, or do I have to drop the $160 for that Walbro pump?

The E2000? I got a large 1/2" NPT (I think) coupler so I could run a female barbed fitting for it, you could do the same.

Unless you want to buy a backup pump and I'll send you what I have for it...
 

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I'm running one of the ford v8 fuel pumps (inline 90psi pump) to my EFI 2.5L V6 in my sammy. I can assure you the return line is well used, as the motor can't burn in an hour what that pump pushes out in a minute.

My return line necks down from 5/16" at the motor to what appears to be 1/8" or 3/16" (metric commie goofy sized shit) hard line at the tank inlet (stock carbed sammy tank, I used one of the vents as a return). I have no problems with the return line being over pressurized. It is held together with crappy hose clamps and line and still seems to hold up.

Mike
 

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Oxjockey said:
The E2000? I got a large 1/2" NPT (I think) coupler so I could run a female barbed fitting for it, you could do the same.

Unless you want to buy a backup pump and I'll send you what I have for it...
Whats the inside diameter of the -8? Can I use -6 for the supply? Basically, I want to be able to run the Ford pump since I already have one and so does every parts store around. The return I will probably run -8. Also, what are you doing about a fuel filter?
 

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AN line goes in 1/16" so -04 = 4/16" or 1/4". -08 is 8/16 or 1/2". Flex line will have a bit smaller ID then hard line.
 

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Discussion Starter #15 (Edited)
chris demartini said:
Whats the inside diameter of the -8? Can I use -6 for the supply? Basically, I want to be able to run the Ford pump since I already have one and so does every parts store around. The return I will probably run -8. Also, what are you doing about a fuel filter?
You can probably get away with -6 for the supply, but the cell has a -8 output so I thought it would be easier.

For the filter, I got a little filter to go between the tank and the pump. I originally bought the BG log, but it's like a foot long and not really practical.

I'll see if I can get a part number.

I ordered the -6 AN crap, I'll have it tomorrow to test the return line.



It's for a carb setup, but it's on the supply side of the pump so it should be fine. If that return line isn't my issue, this gets bypassed at least temporarily.

Edit: I just swapped in the BG filter log thing, and same results.
 

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thanks for the info ox. I will probably head down to Dave's Speed Shop like Rob said to, he helped my dad out when we put a V8 in his S10 this summer. let me know what works out for you.
 

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if you're looking for a parts store available part for your filter, I'm using a stock filter from a 1990 nissan 4 cylinder in mine, it is shaped basically like an oil filter with a nipple poking out of each end. Easy to plumb, easy to mount, and pretty decently sized so it should flow well.
 

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Discussion Starter #18
Update:
I got the -6AN return line, a 3/8" NPT to AN adapter, etc, and it idles OK now. It seems like when it's going into closed loop it's not idling well, but I figure the computer is just going WTF :confused: at this point.

Thanks for all your help!

:beer:
 

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I use two fuel filters on my setup. One mini filter in front of the pump and one stock Jeep filter after the pump.. Those ford pumps are pretty tempermental when it comes to dirt and debris.

RK
 

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Discussion Starter #20
rocksteadyrobk said:
I use two fuel filters on my setup. One mini filter in front of the pump and one stock Jeep filter after the pump.. Those ford pumps are pretty tempermental when it comes to dirt and debris.

RK
I have a second one closer to the motor, it's a generic parts store filter. I only used the fancy red one above because the cell doesn't have a screen vs a tank and pickup. It's cleanable, etc, and it seems to work fine.

Bryan
 
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