Howdy

I ordered a master kit to install a sniper efi system on my 512 streetrod truck. The fuel system works flawlessly with my 950 carb but I want to insure my pickup won’t get uncovered and stall, stutter, or stress the high pressure pump with cavitation so I am planning to make a surge tank to keep the big pump fed.

I am not interested in cutting my tank for baffles, sump, or in tank pump. I don’t want to spend $$$ on a fancy surge tank with a pump in it.

I am considering making a small tank but a few issues are above my pay grade. Pix are worth 1000 words so check out my drawings. If I feed the tank with my stock mechanical pump will that work? Should have enough volume right? As long as I prime it first and it isn’t in a hot place it would be simpler than the other option of using a small low pressure (5ish psi) lift pump to keep the surge tank full.

Second question- my return will go to the bottom of my main fuel cell, so aeration shouldn’t be a problem but would it be ok to vent/return the surge tank to a tee in the return line from the sniper? I want the fuel to circulate and stay cool and not deadhead a lift pump. I also would not want to vacuum lock the surge tank so I want a vent/return on it.

Any thoughts? Thanks!

Radar

I think either of the surge tank ideas will work fine. I do like the one with the electric pump feeding the tank better. That way you could keep it all down on the frame and out of sight.

What kind of fuel tank does this have in it? Seems like a lot of extra hassle, more fittings, lines, and an extra pump to worry about.

Why not just fix the tank and be done with it?

Your surge tank will need its own return line to the tank. If you just run a tee from the throttle body return line the fuel will take the route of least resistance and fill your surge tank.

You could run the TB return to the surge tank only with a separate return from the surge tank to the tank. The surge tank has to be air tight as its the internal pressure that's going to force the fuel through the return line.

Returning fuel back to the main tank offers it the opportunity to cool, I wouldn't run return fuel to the surge tank.

The best idea !!

It’s a 17 gallon tank, rectangular and kind of shallow. I don’t weld aluminum and making some kind of trapdoor anti slosh thing to live inside this rank seems like a ton of work. This thing works perfect and when the bed is on the truck I have a filler plumbed to it from the tub and a vent that goes up the stake pocket.

I just didn’t plan on efi but while my chassis is stripped and I have access to everything I figured now is the time. I think my tank would be OK off the line till 1/4 full or less but hard right turns would be rough.

Agreed that a second pump is an annoying possible failure point. Just weighing my options and would like to build on what I already have instead of replacing or but hering new parts

Side view

Have you looked into any of the fuel mats? Add some fuel cell foam, and this...Might be a cost effective solution.

https://www.holley.com/products/fuel_systems/hydramat/

can't you buy something like that already made up in one neat little package ?

I worked on the last production Imperial which had a TBI unit.. that car
had issues of cornering and the pick up coming uncovered.. after a
ton of work we finally came up with a reservoir inside the tank.. this
solved the problem.. it had a return line to a jet valve then dumped
into the reservoir which would over flow into the tank

If that is a fuel cell flange on your tank then just get a fuel cell drop in EFI pump.

https://www.holley.com/products/fue..._cell_efi_fuel_pump_modules/parts/12-144

My tank only has a bolt in filler neck and a fuel level sender- dunno if it’s a standard size but when the bed is on the truck the screw on cap comes off and the fill hose clamps on there. I don’t see how an in tank pump would help with fuel slosh unless I install some kind of trapdoor or tank in tank sump or at least baffles. I would really like to avoid whittling on my new tank, plus I can tig weld steel but I only have a DC machine so I still have to farm out aluminim. The holley wet mat or whatever looks like an awesome product but it costs as much as a new baffled tank then needs the cank cut open to install.

I’m not the fanciest tig welder but I am confident welding vessels so a surge tank would be basically free. I figured out how to retrofit a second return line for the swirl tank too- I can make a sleeve that goes in the filler hose pierced by a fitting that turns down into the bottom of the tank. That way if I make a little 2 liter tank with a lift pump it will fill quickly and circulate with very little resistance to heat up the gas or an electric pump if I use one and not interfere with the sniper return line.

Drawing

Pics of current carburator fuel system

I got everything plumbed and wired except for switched power and rpm signal which have to wait until the cab and fenders are back on the body. I have high hopes for smooth power and drivability which can only get better if I do a hyperspark distributor and sniper timing control later. I’ll probably switch my electric fan from a probe controlled window switch to a relay and let the sniper run that too.

I ended up making a .45 gallon tank from 2x4 steel tube with an integral bracket for the pumps. Like most of the stuff on this street build it is way heavier than it needs to be with 1/8” wall tube and 3/16” end caps but it was easy to tig up airtight and won’t be breaking any time soon.

I ended up using a 4-6 psi carter which flows more volume than the efi pump supplied in the holley kit. It takes 12 seconds to fill the surge tank and the sniper has a 5 second priming cycle so I ran both pumps off the holley ecu triggered relay.

The biggest concern was whether teeing the surge tank return and efi fuel pressure regulator return together would present too much restriction. They are both 3/8 and use a Y adaptor to a short piece of 1/2 hose then down into the -8 tank return.

With the motor off and both pumps jumped to power there was steady 62psi in the high pressure line. It was the same with the lift pump off, so I think I’m good. The return seems open enough that it can’t build enough pressure to unbalance the regulator and demand on the return system flow should be even lower with the motor running.

Here’s pics of the install. Once the cab is back I will secure the floating lines in the engine bay.

One more pic

I would consider putting check valves in the two returns before they go into the Y. Hate to have a return turn into a feed line if something went wrong.

Not sure what you mean? A lot of people run their high pressure fuel pressure regulator return back to the surge tank to mix with cooler gas and insure their gas supply never runs out. Then the surge tank vents/returns to the tank. I’d rather have cool gas in there from the main supply but if they mix that’s fine- just as long as the efi pump doesn’t suck air. The lift pump is high volume low pressure and the efi pump is lower volume high pressure. The main tank has a rollover protected vent line run up high so if the efi pump somehow out sucks the lift pump and the return becomes the feed that’s unlikely but fine too- as long as the injectors have 60psi and no air bubbles it will be happy.

If the lift pump fails I can bypass it and get home running only the efi pump. If the surge tank gets a crack I can bypass it and deadhead the lift pump into the efi pump. Also if my lift pump ever dies the system could theoretically still work using a siphon effect until the pickup hits air. If the efi pump or FPR ever die I will probably be riding home on a tow truck anyway. It is all a little complicated compared to the old mechanical pump and a carb but I made it easy to service, fairly sanitary, and it will be worth the trouble for the easy startups and drivability of the efi. I hope.

the only thing that makes me a bit uncomfortable, is the amount of rubber line used. other than that, it looks like a well thought out system. that's just me [and rubber hose], not trying to slam you, as i really like your design and execution.

Thanks man I’m trying. I am here on moparts to learn and get constructive criticism- not feeling slammed at all!

I know on a racecar you want almost no rubber to pass tech right? The runs from the back to front are all steel with bubbles flared to retain the hoses. There is a loop of rubber from the tank to the lift pump, then two pieces from the firewall up over the motor. One is regular 3/8 fuel hose and the other is earl’s vaporguard high pressure line. The spot that looks like rubber on the steel return line to the Y is just heater hose zip tied on for abrasion resistance where it could touch the frame. The whole rest of the steel run only touches the rubber lined pico clamps.

So the three places on the system with rubber hoses more than like 4” long to connect metal things are the loop to the lift pump from the tank with the pre pump filter and the two hoses from the engine side of the passenger footwell/firewall. Once the cab is back on I could easily make mounts/supports for hard lines from the throttle body to the firewall with short rubber connectors if that is worth doing. The low pressure line in the back might be stronger if I used some stainless braided hose? I have some but its been sitting around for 5 years or so.

I’m totally open to suggestions. I want this setup to be safe and reliable. I don’t want the expense or bling of all AN connectors everywhere but I don’t want to build dangerous hacked together garbage!

Thanks!

Radar

*and it is missing two hoseclamps 😂 still have to finalize everything but there are no leaks.

I got it running today!

The efi is sweet so far. I went with the hyperspark distributor and I’m super glad I did. I had a stock replacement mechanical advance/magnetic pickup distributor in there for break in and all I did was set total to 34 and later hooked up the vac line. The sniper lets me run plenty of timing at idle and still have a lower number for easy cranking & startup, plus I can add or take away WOT timing on the touch screen. Giving a stock dizzy a twist is easy but the rest of the curve beats the heck out of welding up the slots and swapping out springs, then still needing an ignition killswitch or retard box to avoid kickback.

It starts up immediately which is such a drastic change for me. Every hotrod I build ends up having a race carb which is cool but starting them is like opening a safe then watching water boil.

Anyway, the surge tank is working great so far and I couldn’t be happier