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  1. #1
    FEP Power Member Broncojunkie's Avatar
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    Default Fuel sump, pump, and lines?

    I'm completely redoing the fuel system in my pace car...2.3t to 331 stroker. I have an electric inline pump, fuel regulator, 3/8 braided fuel line with a return.

    I've decided that the best route is to go ahead and install a sump. I already have the tank out and dry, with no signs of fuel whatsoever. So I figure this would be a good time to just do it once and do it right.

    My question is, why do I always see the sump and pump mounted toward the rear of the tank? I already have my pump mounted just in front of the tank, which appears to be a nice little home for it, all tucked away and junk. Is there a reason people do this set up on the backside of the tank instead? If you have it on the front, can you post up some pics to show me how it works out? I'm worried that I'm going to get it all finished and realize that it won't work for some reason or another.

  2. #2
    FEP Power Member Broncojunkie's Avatar
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    By the way, this is a carbed motor and low pressure system.

  3. #3
    FEP Power Member STL79Coupe's Avatar
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    I don't have any pics, but mine is in the front between the tank and rearend. I think most people mount it tin back by the sump for the ease of mounting the pump etc. I now have a coyote in my car with a gravity feed inline 255 pump and had to make a long bracket to try and get it lower then the sump.
    Keith formerly STLPONDS
    '79 V8 coupe in the works!
    Build thread http://vb.foureyedpride.com/showthread.php?t=89153

  4. #4
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    My understanding is that, for light trucks and suv's, you want the fuel pickup at the point where fuel will be when climbing a hill.
    The same vehicles usually have rear-sump oil pans so that the oil will be where needed when the engine is under heavy load, that is, when climbing a hill.
    For drag racing, weight transfer and acceleration will cause fuel to shift to the rear of the tank. If the tank is full, this is less of a problem, but a full tank is extra weight.

  5. #5
    FEP Power Member Broncojunkie's Avatar
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    Ok that makes sense. I think I'll be ok with a front- mounted setup. I don't think I'll be standing wheelies and running low on fuel lol
    Last edited by Broncojunkie; 12-29-2017 at 03:18 PM.

  6. #6
    FEP Senior Member droopie85gt's Avatar
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    I think it has to do with electric fuel pumps don't like to have to 'suck' the fuel uphill. So people mount them low by the sump.
    1985 GT, Sunroof, 5 Lug, Rear Discs, 01 Graphite Bullets, 88 forged piston shortblock, 2.02/1.60 Alum heads, Weiand Stealth, Holley C950 TBI, BBK Long tubes

  7. #7
    FEP Power Member Broncojunkie's Avatar
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    Quote Originally Posted by droopie85gt View Post
    I think it has to do with electric fuel pumps don't like to have to 'suck' the fuel uphill. So people mount them low by the sump.
    True, but I don't think the pump will be any lower if mounted on the rear as opposed to in front of the tank. And regardless, if you can get it down toward the bottom of the tank at the rear, it will hang down and be unsightly. I noticed it on my 82gt, which is mounted just like that. Probably wouldn't be noticeable on my 88gt with the rear bumper that comes down lower to match the ground effects. Where I have mine mounted, it's not at the bottom of the tank, but roughly around half way up. It will need to pull a little, but I read up on it and most people aren't able to get them way down low and they still work just fine. If I have problems, I'll make a drop bracket for it. The only thing I'm not 100% on is whether I have everything out of the way enough for the exhaust. I think I'll be ok, just judging by how my other cars are.

  8. #8
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    Rear mounted pumps and sumps are for drag racing.

  9. #9
    FEP Power Member Broncojunkie's Avatar
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    My original plan was to just drill into the tank and wiggle in a couple bulkhead fittings toward the bottom. I'm just not sure how hard it would be to get them tight and I would worry about them coming loose or leaking. The sumps come with threaded bungs and you don't have to worry about threading them in. Of course, it's a trade-off because you have to weld the sump pan in and that has to be leak-free.

    I'd really like to see or hear about how others are doing theirs.

  10. #10

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    Here's the fabricated fuel tank pickup from the Mustang Performance Handbook by William R. Mathis...





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    Mike
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  11. #11
    Moderator wraithracing's Avatar
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    Along the lines of the Mathis modification, here is a drop in option if you don't want to sump the tank.

    Name:  Fuel Inlet.JPG
Views: 663
Size:  40.5 KB

    https://lmr.com/item/GRN-GMTI7998/19...et-Fuel-System
    ​Trey

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  12. #12

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    Quote Originally Posted by wraithracing View Post
    Along the lines of the Mathis modification, here is a drop in option if you don't want to sump the tank.

    Name:  Fuel Inlet.JPG
Views: 663
Size:  40.5 KB

    https://lmr.com/item/GRN-GMTI7998/19...et-Fuel-System
    I had 2 threaded bungs welded on the front of my tank 1 down low and another near the top for the return only problem im having is if i have less than half tank i lose fuel to the pump if the car leans too much in a right turn , a problem without having an internal sump in the tank.

    Sent from my LG-D852 using Tapatalk

  13. #13
    FEP Power Member STL79Coupe's Avatar
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    He won't be able to use the drop in pick up on his 79-80 tank unless he drills an access hole in the top for the pickup.
    Keith formerly STLPONDS
    '79 V8 coupe in the works!
    Build thread http://vb.foureyedpride.com/showthread.php?t=89153

  14. #14

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    My car (1982 GT) was a bracket racing car, and had the drop in (like LMR above) with a Edelbrock Hi Volume mechanical pump - it worked great although I didn't like how I had to run the lines . Now I have a Holly blue pump behind the rear bumper and a Franks Tanks sumped tank - it works great too.
    1982 Mustang GT - Black with Red Interior
    Engine: Former 306 with AFR 185's, F Cam, RPM Air Gap, Barry Grant 650, Ford Racing shorties, and MSD 6AL. Coming soon a 408. Transmission: Broader Performance C-4 with Reverse Manual Valve body and Ultimate Convertor Concepts 3500 Stall.
    Rearend: 8.8 with 3.73 Gears and Moser Axles.

  15. #15

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    With a '79 to early '81 tank's front angled pick up hole, a fabricated pick up like the Mathis one should actually work very well, especially for go fast situations, modified with a shorter or longer 45-degree (to the rear) cut pick up tube tip position down juuuuuust above the tank floor at the back/bottom... and an external filter installed prior to whatever external fuel pump...
    Last edited by Walking-Tall; 01-11-2018 at 12:56 AM.
    Mike
    1986 Mustang convertible ---> BUILD THREAD
    Past Fox-chassis "four eyes":
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    1986 Ford Thunderbird ELAN
    1980 Capri RS Turbo

    Work in progress website ---> http://carb-rebuilds-plus.boards.net/

  16. #16
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    If you are running a return line back into the tank, it must go all the way back down to the bottom of the tank, just like the pick up tube. Why? because the high volume flow of the returning fuel will aerate the fuel (if dropped in from above the fuel level in the tank) and cause the pickup tube to such a lot of air with the fuel and cause a lean out. The greater the flow, the more air it will suck up.

  17. #17

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    ^^^ Very true. Return tube should be submerged, and even directed away from the pick up tube.
    Mike
    1986 Mustang convertible ---> BUILD THREAD
    Past Fox-chassis "four eyes":
    1983 Mercury Cougar LS
    1986 Ford Thunderbird ELAN
    1980 Capri RS Turbo

    Work in progress website ---> http://carb-rebuilds-plus.boards.net/

  18. #18
    FEP Power Member Broncojunkie's Avatar
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    I have a tank that is already sumped, but it's for a later efi car. How hard would it be to make it work in the 79?

  19. #19
    FEP Super Member xctasy's Avatar
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    http://vb.foureyedpride.com/showthre...68#post1869268
    Mr Basin Motorsports from Sprague River, OR

    79-80.5 Carb fuel tank verses later EFi fuel tank

    Quote Originally Posted by Basin Motorsports View Post
    Before I hauled off the crashed notchback, I spent a few minutes documenting the difference in the carb vs EFI fuel tanks. I see this question pop up once and a while and hopefully it answers a few questions.

    .....
    Note well

    This is a primary safety issue. Stock 1983-2004 EFi Fox derived tank and fuel pump, great.

    The net positive suction head a modern staged fuel pump can dead lift is still not as good as any old diaphram engine mounted fuel pump, so all EFi cars require a stillage pot and return line areation protection.

    The best example of danger is a tail up stall at maximum gradient emply plus 33 US fluid ounces of gas. Thats the emply plus 1/4 US gallon test. On my 1998 Explorer, it stalled on a 8% gradient with 5 gallons in it. Maximum statutory gradient is about 12% . Unless your in San Fransico...

    Yet nose up, it would scavage to the last drop.

    The Fox to SN95/99 Mustang tank eliminates the need for a stillage pot due to the tank shape, but all these modern Fitech/HolleySniper/MegasQuirt and EECIV retro fits put you in a serious risk of


    1. road camber,

    2. road gradient and

    3. net postive suction head zero fuel delivery issues.

    Fords 1983 on EECIV twin pump or later single pump fuel tank is probably one of the best systems at the sub 325 hp level around.

    The 1998 Explorer EFi fuel tank, potentially fatal on steep trail.

    On my 1996 Nissan Stagea (AWD R33 Skyline or 810 Maxima derivative), just a 3% road lean (normal camber on a tar macadam road), it would run out of gas with even 2.5 gallons or 50 miles of fuel in reserve.

    There is a reason I detest retro fit EFi systems, because the factory design safety is gone, and on a high way or emergency situation, fuel cut to an engine just isn't acceptable. Added to the electric fuel pump earthing issues and preciptate issues with modern Ethanol based gas, a US Coast Guard style "Granma's minium standard" for EFi fuel pump operation should be used for peace of mind.

    The common thought is just don't let you gas level drop below 1/4 full, but that isn't the asnwer to the the actual root problem.

  20. #20
    FEP Power Member Broncojunkie's Avatar
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    That video was informative, but man...he mentions at the end to stay tuned for a video showing the later model tank swap into the earlier car. I looked through his videos and don't see it.

    Anyway, I think the best route is to stick with the 79 tank. It's in good shape, so that's one less tank I'll have to buy later on down the road. The 82 and 86 very well may need tanks, once I start tearing into those builds. I'm hoping the sump pan shows up tomorrow. I'm not much of a welder, so I may take it to my buddy and see what he can do with it.

  21. #21
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    Just curious why you think you need a sump in your gas tank. On my carbed 85 Mustang, I used the stock gas tank and sender/gas pickup tube, along with a Holley "blue" electric fuel pump attatched to front edge of the spare tire well. My Mustang was a factory 4 cyl. car, I ran a new 3/8" steel line from the tank to a Holley regulator in front of the LF strut tower, and from the regulator to the Holley carb. My engine is a 331, that does get drag raced, and does do wheelies, and the stock tank and pickup tube seemed to be up to the task, running mid 1.3 second 60 foot times, and 10.3/4 second ETs @ 128 MPH in the 1/4 mile.
    1978 Fairmont 2 door sedan, 428CJ 4speed. 9.972ET@132.54mph. 1.29 60 foot
    Replaced the FE big block with my 331/4 speed in my Fairmont, best 10.24ET @128 MPH.
    1985 Mustang LX hatchback NHRA Stock Eliminator 302 4 speed best in legal trim 12.31@107 mph, but has gone 11.42@115 with aftermarket intake, carb, and iron Windsor Jr. heads.New for 2012! 331 cube SB Ford, AFR 185 heads, solid flat tappet cam, pump gas; 10.296ET@128.71 mph, 1.37 60 foot.
    1979 Zephyr Z7, all original 302 auto, 2nd owner.

  22. #22
    FEP Power Member Broncojunkie's Avatar
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    Quote Originally Posted by mcfairmont View Post
    Just curious why you think you need a sump in your gas tank. On my carbed 85 Mustang, I used the stock gas tank and sender/gas pickup tube, along with a Holley "blue" electric fuel pump attatched to front edge of the spare tire well. My Mustang was a factory 4 cyl. car, I ran a new 3/8" steel line from the tank to a Holley regulator in front of the LF strut tower, and from the regulator to the Holley carb. My engine is a 331, that does get drag raced, and does do wheelies, and the stock tank and pickup tube seemed to be up to the task, running mid 1.3 second 60 foot times, and 10.3/4 second ETs @ 128 MPH in the 1/4 mile.
    I really didn't trust the 39-yr-old lines and figured the smaller factory tubing was near the limit. I figured since I was running new lines anyway, I'd go ahead and upgrade them.

    I ended up having the sump pan welded on. It has 1/2" bungs, although I ran 3/8" braided line. It turned out great and I love the setup. Sometimes I like to improve on things even though the factory stuff would have worked ok.

    But now you have me curious about your car. What are the specs? Auto or standard? I'm getting excited about this build since I just got the car running a couple days ago. Motor sounds great. I won't get to drive it till I get the brakes lined out and probably the 8.8 rear and 3.73 gears installed.

  23. #23
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    I originally raced my 85 Mustang as a NHRA legal Stock Eliminator car, so all steel, including factory flat hood, battery under the hood, full factory interior etc. In Stock, I had to use the factory unported, stock sized valve E5 heads, stock, unaltered E4 intake and E5 carb, no more than stock lift (.444" max). The best it ran in Stock (M/Stock) was a 12.32 @107 mph. At first I ran the stock T5, but later converted to a much stronger Jerico 4 speed.Name:  PhotoScan6 (4) - Copy.jpg
Views: 552
Size:  112.3 KB Name:  PhotoScan6 (3) - Copy.jpg
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    When I installed the 331, I left everything else on the car identical as when ran in Stock. The 331 has flat top pistons, about 10.5 compression, runs fine on Chevron Supreme), out of the box AFR 185 heads, a Ford Motorsport single plane intake with a stock Holley 650 DP. Cam is a flat tappet solid (.560" lift), headers are 1 5/8" FlowTech long tubes. 10" McLeod Soft Lok clutch, the same Jerico 4 speed (3.19 low gear), and 4.88 gears. With 9x29" Hoosier slicks, best 60 foot time was 1.37, best 1/4 mile 10.29 @128MPH. The car weighed 3050 lbs with me in it.
    Last edited by mcfairmont; 01-14-2018 at 03:08 PM.
    1978 Fairmont 2 door sedan, 428CJ 4speed. 9.972ET@132.54mph. 1.29 60 foot
    Replaced the FE big block with my 331/4 speed in my Fairmont, best 10.24ET @128 MPH.
    1985 Mustang LX hatchback NHRA Stock Eliminator 302 4 speed best in legal trim 12.31@107 mph, but has gone 11.42@115 with aftermarket intake, carb, and iron Windsor Jr. heads.New for 2012! 331 cube SB Ford, AFR 185 heads, solid flat tappet cam, pump gas; 10.296ET@128.71 mph, 1.37 60 foot.
    1979 Zephyr Z7, all original 302 auto, 2nd owner.

  24. #24
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    Quote Originally Posted by Broncojunkie View Post
    That video was informative, but man...he mentions at the end to stay tuned for a video showing the later model tank swap into the earlier car. I looked through his videos and don't see it. .
    Here is the EFI tank in a carb car.

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