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EFI and small stock fuel tank

51K views 68 replies 36 participants last post by  1bad68cat 
#1 ·
As I get ready to install the engine, etc I was thinking about my EFI setup and the stock 16 gallon tank. I've heard the stories...where fuel starvation occurs in fast acceleration on <1/2 tank during quick accel/decel or in turns.

An option is to install a '70 22 gal tank with a '70 EFI fuel sender. All that is needed here is to modify the filler tube to fit the higher height of the 22 gallon tank.

The question is for you all out there that have done the EFI swap and kept your 16 gallon tank. How is your fuel feed? Any issues? I have the Ron Morris EFI fuel conversion ket. Just wondered if the 22 gallon will make that huge of a difference. This is not a daily driver, so how many miles I get to a tank doesn't matter to me.

Thoughts?
 
#4 ·
Great question

This is a great question, and I hope you get a lot of responses from others who have done this conversion. I've seen some pretty excellent installs.
I had started on baffling and sumping the stock 16 gallon tank and adding an intank fuel pump setup, but decided the 16 gallon tank was too small for what I wanted. There is a thread on here somewhere with pictures of what I was doing.

After some long time thinking and searching, here's the conclusions I came to (right, wrong, or just anal :shrug: ):

1). Best not to go below 1/4 tank on an EFI car because the lower the fuel level, the warmer the fuel and The more aeriated the fuel becomes, the hotter the pump runs (leading to pre-mature failures, and fluctuating stoich).
2). That leaves about 12 usable gallons in a stock tank, which is about 240 miles cruising range. Which seems a bit short for touring, to me.
3). I really like the idea of keeping the pump in the tank. It's quiet, cool, and out of the way. No catch tanks, minimal connections, and a very tidy appearance.
4). No fuel lines in the trunk! the thought of fuel lines in the trunk scares the heck out of me.
5). 22 gallon tank sits up too high to put a flat plate over the trunk floor.

So based on that criteria, I bought a '69 tank (20 gallons), allows a flat plate across the trunk floor), and a Tanks, Inc fuel pump kit. Optimally this would have been mounted in the left rear corner with the tray facing forward. My arms are too short to have been able to hook up the lines inside the front of the tank, so I opted for the left front corner, with the tray facing the left side.
http://i104.photobucket.com/albums/m184/66Runt/IMG_1699.jpg

I ran a 3/8" hose from the pump to the -AN 8 bulkhead, and then 1/2" hose to the filter and engine. For the return, I am using the stock '69 sender, and 3/8" hose. I did not want the hot return fuel to go back into the pump tray, and staying above 1/4 tank there won't be a starvation issue.
The capped off Bulkhead is for a second pump, should I end up going to 60# injectors and more boost. I didn't want to have to mess with drilling or welding on a "used" fuel tank down the road.
http://i104.photobucket.com/albums/m184/66Runt/IMG_1697.jpg

I decided not to run the fuel lines down the tunnel, like stock, due to exhaust pipe heat, and incase of a catastrophic clutch or driveline failure (just a bit nervous of the prospect of a flame thrower cotterizing the area of leg that used to have an ankle attached :loco: ). So I ran them down the frame (and subframe) rail, and up into the right side behind the shock tower. Still have to finish installing the nut-serts for the clamps. I went through the tunnel brace to keep things up and tight, and away from the header. going from this support into the engine compartment the hoses will be inside of heat shield tubes.
http://i104.photobucket.com/albums/m184/66Runt/IMG_1698.jpg
 
#28 ·
this is a great question, and i hope you get a lot of responses from others who have done this conversion. I've seen some pretty excellent installs.
I had started on baffling and sumping the stock 16 gallon tank and adding an intank fuel pump setup, but decided the 16 gallon tank was too small for what i wanted. There is a thread on here somewhere with pictures of what i was doing.

After some long time thinking and searching, here's the conclusions i came to (right, wrong, or just anal :shrug: ):

1). Best not to go below 1/4 tank on an efi car because the lower the fuel level, the warmer the fuel and the more aeriated the fuel becomes, the hotter the pump runs (leading to pre-mature failures, and fluctuating stoich).
2). That leaves about 12 usable gallons in a stock tank, which is about 240 miles cruising range. Which seems a bit short for touring, to me.
3). I really like the idea of keeping the pump in the tank. It's quiet, cool, and out of the way. No catch tanks, minimal connections, and a very tidy appearance.
4). No fuel lines in the trunk! The thought of fuel lines in the trunk scares the heck out of me.
5). 22 gallon tank sits up too high to put a flat plate over the trunk floor.

So based on that criteria, i bought a '69 tank (20 gallons), allows a flat plate across the trunk floor), and a tanks, inc fuel pump kit. Optimally this would have been mounted in the left rear corner with the tray facing forward. My arms are too short to have been able to hook up the lines inside the front of the tank, so i opted for the left front corner, with the tray facing the left side.
http://i104.photobucket.com/albums/m184/66runt/img_1699.jpg

i ran a 3/8" hose from the pump to the -an 8 bulkhead, and then 1/2" hose to the filter and engine. For the return, i am using the stock '69 sender, and 3/8" hose. I did not want the hot return fuel to go back into the pump tray, and staying above 1/4 tank there won't be a starvation issue.
The capped off bulkhead is for a second pump, should i end up going to 60# injectors and more boost. I didn't want to have to mess with drilling or welding on a "used" fuel tank down the road.
http://i104.photobucket.com/albums/m184/66runt/img_1697.jpg

i decided not to run the fuel lines down the tunnel, like stock, due to exhaust pipe heat, and incase of a catastrophic clutch or driveline failure (just a bit nervous of the prospect of a flame thrower cotterizing the area of leg that used to have an ankle attached :loco: ). So i ran them down the frame (and subframe) rail, and up into the right side behind the shock tower. Still have to finish installing the nut-serts for the clamps. I went through the tunnel brace to keep things up and tight, and away from the header. Going from this support into the engine compartment the hoses will be inside of heat shield tubes.
http://i104.photobucket.com/albums/m184/66runt/img_1698.jpg
very nice!!!!!
 
#5 ·
That's an awesome write up Scott, thanks for all the details. I am going to print this off and re-read it 10x to fully understand all that you've done. Seems like you got yourself the perfect solution for this.
 
#7 ·
I did pretty much what 66 Runt did but I ran my fuel lines on top of the tank then covered the tank with a 14 ga steel plate to provide a 'real' trunk floor, effectively isolating the lines from the trunk. I also put the steel divider behind the back seat (I'm real paranoid about gas in the cabin). I used the Tanks pump, but bought a new 20 gal tank for a 69. I mounted my pump as far back and to the right as I could get it. I also used the GM fuel tank vent (I can look up the part number if needed).

It works great, is quiet and I have 3500 miles on it so far with no problems.

Here's a little write up on mine. Also do a search on HoosierBuddy. He did a Tanks pump as well. Fuel pump install
 
#8 ·
what I'm planning on doing is leave the tank stock...use dual in-tank 255lph warlboros, and use a fuel pump canister like my neon's...heres a picture of the neon canister...



not that the neon canister is all that great...however it provides a simple solution to the problem, the sock at the bottom draws fresh fuel in...which the pump sends to the rail through a regulator which sits on top of the canister(metal thing at the top) excess fuel is returned to the inside of the canister through an internal line(not to the tank) the fuel pump actually has two inlets...one that draws fuel through the external canister sock and an additional inlet that draws fuel through another sock inside the canister...this is used when the fuel coming through the external sock is insufficient for whatever reason(heavy cornering...empty tank, whatever)...regardless I am sure a lot of modern cars have these canisters...I was planning on modifying a neon canister for several reasons...

1. I am very familiar with them...having modified several in the past to supply large amounts of fuel in my turbo neons.
2. I happen to have an extra one right now(as well as an extra 255lph neon pump)
3. its fairly compact as far as canisters go...it should fit through the stock sender hole

its possible i wont be able to use a neon canister...regardless though I am going to base my design on it simply because it works and I'm familiar with the setup
(I do see a couple hangups with my solution...the canister was never designed for 2 pumps....its possible I may not have enough space left for sufficient fuel after adding the second pump...the other being I dont have a tank yet, so I cant tell for sure it will fit...however it works on a swing arm...so I dont think that tank angles will be much of an issue...not sure what I'll do about the sender, but I'll figure something out)
 
#9 ·
It's not so much the capacity (stock Fox Mustang tanks are 15.6 gallons), but having the pump properly baffled for EFI use and low fuel levels, as already noted. Lots of EFI conversions using the stock 16-gallon tank for sure. Go 20-gallon if you want more cruising range and just tweak the filler neck opening...
 
#10 ·
This was an area of the EFI conversion where I thought I'd try cutting a corner.

I used a stock 16 gallon tank with the Ron Morris EFI sender unit and an externally mounted in-line fuel pump.

No sump. No fancy work.

As with anything else, I believe that it's possible to "over think" things. Keeping it simple has worked fine for me.

I've got well over 5000 miles on the car now and have never had an issue. I'll usually top off the tank when it gets down around 1/4 tank, but not because I'm worried about fuel starvation, I'm just worried about running out of gas as with any other vehicle. Why run around with 1/4 tank.. or less?

I've pulled the front tires off of the ground during a hard launch and have done donuts like a crazy HS school kid without issue.



I'm using a Ford stock high flow in-line fuel pump and the only time it's even slightly audible is the split second between "key on" and "ignition". Other than this brief time, no-one could possibly hear it running.

Here's a picture:

 
#15 ·
I have a stock tank with an external pump and the fuel line is plumbed into the tank where the drain hole used to be. I've run the tank pretty low and have never had any issues with fuel starvation in 2 years. The external pump is a bit noisy, although I was able to get it quieter by putting a thick piece of rubber between the pump and the frame rail it is mounted to.
Hi Trevork;3891642! I'm interested in how you setup your fuel tank. Could you explain what you did exactly and what parts or part numbers you used to achieve the conversion.

I have a 1956 Chevy Short Box Step Side P/U truck with a GM 350 TBI engine. I have the 1964 Mustang fuel tank as I would like to mount it under the bed. I just don't know how to convert it for the 350 TBI Engine. As simlpe and cheap as possible.
Thanks Buddy.
Reg.
Cobra47sc
 
#11 ·
Just my $.02, but if I had it to do over I would go with an in tank setup. I know it's probably going to be considered lame, but my external pump makes a crapload of noise (and not cool noise like a throaty cam/idle/exhaust rumble, more like an irritating whine that never stops). Maybe I just got the wrong type of pump, but good lord is it ever loud.
 
#12 ·
I doubt I would mind the noise of an external pump myself, but I just want to try an internal pump setup, however I agree, an external pump setup works perfectly fine for most people...warlboro 255lph pumps actually tend to be quieter than a lot of stock fuel pumps from my experience...also ford trucks(F150s) in the 90s used inline pumps that were quiet as well...you might need two in parallel to feed a high HP engine though
 
#13 ·
I have a stock tank with an external pump and the fuel line is plumbed into the tank where the drain hole used to be. I've run the tank pretty low and have never had any issues with fuel starvation in 2 years. The external pump is a bit noisy, although I was able to get it quieter by putting a thick piece of rubber between the pump and the frame rail it is mounted to.
 
#14 ·
Hi Trevork;3891642! I'm interested in how you setup your fuel tank. Could you explain what you did and exactly and what parts or part numbers you used to achieve the conversion.

I have a 1956 Chevy Short Box Step Side P/U truck with a GM 350 TBI engine. I have the 1964 Mustang fuel tank as I would like to mount it under the bed. I just don't know how to convert it.
Thanks Buddy.
Reg.
Cobra47sc
 
#19 · (Edited)
Hey Buddy! I think this is may work.

How to setup the fuel run for a TBI Engine and with a 1964-68 16 gallon fuel tank.

Parts New Mustang 16 Gallon fuel Tank with drain plug.
1) New low volume fuel pump.
2) New Universal Complete Fuel Surge Tank 2 Liter Swirl Pot System Aluminum Surge tank. http://www.ebay.com/itm/Universal-Co...a22d00&vxp=mtr
3) New Fuel filter.
4) High Volume fuel pump.
5) New fuel filter.

This is what I think will work for my setup.
It’s going in a 56 Chevy Step Side Short Box Pick Up Truck.
I’m just getting my info from fellow builders and tiring to get a grip on this fuel tank TBI conversion for my GM 350 TBI engine with a Mustang Fuel Tank. The truck is still covered for the winter but need to be ready for when the weather gets better and maybe this will help someone else out in the process.

I have never set up or installed a TBI engine before, so bear with me. If I’m not in the ball park please help me out!!!

What I figured on doing is.
Add a AN fitting in the fuel tanks drain plug location and from there to a low volume fuel pump then to a 10 to 40 micron filter, then from there to a fuel surge tanks line in.

From the serge tanks line out to a high volume fuel pump (or whatever PSI I need for my engine) then to a 10 micron fuel filter and from there to the TBI/Carb.

For the return line using the same type 3/8” fuel line, run it back to the surge tank and from there to a newly drilled in line fitting on the left or right side of the fuel sender.

Now there maybe some over kill on the filters and there may be an issue with or if I need a vent for the tank, but I think if that is a problem I could just use a fuel filler shaft with a AN fitting for the vent.

The fuel tanks original fuel sender is just for the gauges. Not sure if I could use the fuel line from the sending unit for something.

Ok to all the brains out there will this work? That is the question!
Thanks for everyone’s opinion and help.
Reg . Cobra427sc.
 
#23 ·
Hey Fox Rodder! If you could break that down so I could understand the complete fuel line run. As from were to what and so on. As I'm not sure of the tank you have. Mine has a drain plug that I could use for an AN fitting and then go from there.....to???

My engine is just a Regular 1988 GM 350 TBI. I'm sure the psi is low also somewhere in the 12 to 18 psi range...I'd have to look it up as this is all new to me. The TBI fuel setup is definitely screwing up my mind. I'm probably over thing it but.... I'm new to it so just tiring to find something that works and is cheap. :)))
Thanks.
Reg.
Cobra427sc.
 
#21 ·
Something to consider...

I don't use a stock tank anymore, when I did, I had plumbed in an 8an bulkhead at the back corner to feed the 1/2" line I was using. I thought this was okay, it never appeared to lean out on the street, however at the drag strip it would lean out part way down the track.

When I installed a wide band O2 sensor it was easy to see the engine going lean (even on the street), it was not breaking up like it did at the strip, just going noticeably lean, I could not feel it or at best it was subtle. On the street you rarely if ever go full throttle for more than a short burst so the fuel bowls can mask fuel delivery issues.
 
#24 · (Edited)
Hey JamesWnew! That looks pretty sweat!! Not sure where all the lines are running but it looks like you did your work on it.

Now if you wouldn't mind breaking it down for me with parts list and what you used. That would be really cool...and pictures even better!
Also what did it end up costing you?

I'm new to the TBI engine and really not sure what to do for my 64-68 Mustang fuel tank to set it up for the TBI. My engine is just an 1988 GM 350 TBI so noting special as the psi is not that high for this engine.

I'm just tiring to get around what will work well and not cost an arm and a leg.
It's for my 1956 Chevy step Side P/U truck so I won't be racing with it.

Any help would be great and any info on how it runs with the setup?
Thanks Buddy really nice work!!
Reg.
Cobra427sc.
P.S I would love to come to Greenville...but I live in Montreal, Canada...just a little bit to far for me. Thanks for the invite though buddy.
 
#25 ·
Sure, come on down...it's been aboot the same temperature here this winter!
The brace is a section of 1.5" x 1/8" angle iron that runs the width of the fuel tank. It picks up the holes along the front lip of the tank. I welded sections to mount the pump and the tank.


The fuel is drawn from the gas tank up through the low pressure pump (Carter P60430) lower right and into the accumulator tank from BC Broncos. This tank holds a half quart of fuel and circulates back to the gas tank through the tank drain port via the tee fitting above. The high pressure pump (Airtex E2000) draws from the holding tank and feeds the fuel injectors. The return line from the injector manifold feeds into the other side of the tee, returning fuel to the tank. Both the fuel pumps can be sourced from Rockauto.

 
#27 ·
While the execution of this design looks very nifty and will most certainly work, it sure strikes me as being an unnecessarily complicated solution. Seems a proper small sump would do just as well for 99% of the street applications we are describing. Another thing that helps a ton is keeping the regulator and return circuit short and close to the tank (e.g. similar to a “returnless” system). Just a couple of thought-starters.
 
#31 · (Edited)
Hey SWPruett! So far that is the right answer. You see the question for me was that I'm using a 1988 TBI 350...but is in my 56 Chevy P/U truck and I'm using the 1964-68 16 gallon fuel tank with the drain plug. So I have never setup this engine or fuel run to the engine and back.The tank does not have baffles in it.

So what was the easiest way with a low cost?
From another site this is what BO185 said.

Ok so from the EFI sender you linked. http://www.mustangsplus.com/xcart/1970-EFI-Fuel-Tank-Sending-Unit.html
You run a 3/8'' fuel line to a Frame 3/8 clear plastic fuel filter mounted on the frame rail clear of the exhaust. Then fwd of it with 12'' mount the fuel pump low on the frame. Then run a TBI stock steel fuel filter. Then 3/8'' line straight to the TBI unit. Then run 5/16'' straight to the return port provided on the sender.

You will need a relay for the fuel pump triggered by a signal wire from the PCM.

So what to use for the line. I actually use steel brake line. And cut and flared the ends with GM fuel fittings. But use short jump rubber line to make the hook ups. Using Fuel injection rated rubber line fwd of the fuel up as needed. Now this is really really cheap. And not for everyone.

Next you could look at pick and pulls and find the steel braid stock GM truck lines and make them work with some mods. The good thing is this will get you to were the high pressure TBI fuel filer on the rail is then you only have worry about the low pressure lines.

Next you could convert to AN fittings and run A/N braided lines which is expensive.

Reg.
Cobra427sc.
 
#38 ·
In my 65 mustang with a stock tank and mechanical pump when I go racing if the fuel level gets below half'ish in the tank when I hit third gear I go lean and slow down enough that I need to lift slightly to allow everything to catch back up. Doesn't happen with a full tank...so slosh can be an issue depending on the application....and with an electric pump it has always been conveyed (at least to me by others) the easiest way to shorten your electric pumps life is to let it try sucking air frequently
 
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