Fuel Cell or tank mod?

Yes, I've seen Z-mans setup.....very nice for sure. Gordon also ran his lines from the bottom of the tank

http://www.vettemod.com/forum/showthread.php?t=3271

but don't see that he made the bottom sump to prevent the pump from sucking air. Maybe you don't need it anyway, but either one of these seems to me to be easier than dealing with a fuel cell. I think I would just take it to someone and have it welded if that's the route to go rather than trying to weld it yourself.

Sure would be nice to just pull the old unit out of our tanks and plunk in a new one. Lots of good info here on fittings etc.:

http://forums.corvetteforum.com/c3-...-f-a-s-t-ez-efi-is-anyone-using-this-yet.html

I think the hardest part of these FI conversions is definately dealing with the fuel supply issues:skeptic:
 
Z-man does has a sump, in a sense. The remote reservoir is the sump. And fuel cells are easy, if it fits. Buy it, strap it down, hook up the lines and you're golden. As far as welding, I'm trying to avoid it. But if it has to be done, I can't do it, so no worries about me trying :D I'll check out that bottom thread later on and see what I can dig up. Thanks for the tip :thumbs:
 
TopGunn said:
Yes, I've seen Z-mans setup.....very nice for sure. Gordon also ran his lines from the bottom of the tank

http://www.vettemod.com/forum/showthread.php?t=3271

but don't see that he made the bottom sump to prevent the pump from sucking air. Maybe you don't need it anyway, but either one of these seems to me to be easier than dealing with a fuel cell. I think I would just take it to someone and have it welded if that's the route to go rather than trying to weld it yourself.

Sure would be nice to just pull the old unit out of our tanks and plunk in a new one. Lots of good info here on fittings etc.:

http://forums.corvetteforum.com/c3-...-f-a-s-t-ez-efi-is-anyone-using-this-yet.html

I think the hardest part of these FI conversions is definately dealing with the fuel supply issues:skeptic:
Click to expand...

I can unnersand a BB putting out 500+ having a fuel issue with FI, but for Christsakes, I can't see any issues....my mild <400 hp 355 has been fine for years now....stock fuel lines, frame mounted pump under the tank, no problems what so ever....change the filter once in a while.....

sure I have had 'problems' but the pump and the location, and the overall POWER is not among them...no sump, just keep 2 gallons in the tank bottom, sure I would LIKE to do a safe sump setup some day, and maybe will, but the present stock '72 tank and pump in back pushing forward, return line hooked up per stock configuation....works well....

now I have found something interesting....to use AEROQUIP style steel reinforced fuel lines for the supply, it does help smooth out the engine...

do not use rubber hose, even rated for FI at 250 psi....good but not good enough...

:amazed:
 
You make some good reasonable points Gene, I think sometime these things get carried away designing for the moon and loosing sight of what's necessary for the application. Did you just put a feed line in the bottom of the tank to feed the pump?
 
TopGunn said:
You make some good reasonable points Gene, I think sometime these things get carried away designing for the moon and loosing sight of what's necessary for the application. Did you just put a feed line in the bottom of the tank to feed the pump?
Click to expand...

NO, my '72 has a ~2" hatch/hole in the bottom rear, toward the pass side...I just used the stock pickup with a fresh sock filter on it, then a filter before the pump, the return line remained stock, as with the evap canister hookup...in fact that evap canister had a valve failure, it's always open, so fine, it goes to the induction before the throttle blades, as does the line from the valve cover...

I mounted the pump to the rear frame rail near the tank, just wrapped it in a old cut up rad hose, and used a hose clamp...snug as a bug in a rug in that channel there....short hop to the fuel line going forward....

Fuel pump relay is on the firewall, near the booster...+ wire was run inside, down the console, throughthe package wells, then parallel to the gas lines... pump grounded to the frame back there....I scrape/sand till naked steel, then use a star washer for the ground lugs, then bury it all in RTV rubber, totally waterproof then...forget about corrosion...

I used the cheaper Erol's 250 psi red marked 3/8 line in the back, seems fine there, but when replacing it up front with the heavy Aeroquip steel reinforced line and using good clamps from a industrial supplier here, I noticed a goodly improvement in the idle, something about the pressure waves in the lines from the pulsing injector batches, finally made me change that line setup....funny, as it never gave any problems with the stock TPI setup, but as the years went by the change to LT1 induction brought up that problem.....:D
 
mrvette said:
NO, my '72 has a ~2" hatch/hole in the bottom rear, toward the pass side...I just used the stock pickup with a fresh sock filter on it, then a filter before the pump, the return line remained stock, as with the evap canister hookup...in fact that evap canister had a valve failure, it's always open, so fine, it goes to the induction before the throttle blades, as does the line from the valve cover...D
Click to expand...

Boy you lucked out there, the 75 has the pickup routed down from the top of the tank. I'm just getting started with this so my learning curve is straight up........I think Greg mentioned a pump that was a drop in except for the mounting flange. Wonder about the gage accuracy, pickup height etc. if it wasn't for the 75 tank. Might be easire to just drill the hole at the bottom and be done with it. Thanx for the other good info. also :drink:
 
TopGunn said:
mrvette said:
NO, my '72 has a ~2" hatch/hole in the bottom rear, toward the pass side...I just used the stock pickup with a fresh sock filter on it, then a filter before the pump, the return line remained stock, as with the evap canister hookup...in fact that evap canister had a valve failure, it's always open, so fine, it goes to the induction before the throttle blades, as does the line from the valve cover...D
Click to expand...

Boy you lucked out there, the 75 has the pickup routed down from the top of the tank. I'm just getting started with this so my learning curve is straight up........I think Greg mentioned a pump that was a drop in except for the mounting flange. Wonder about the gage accuracy, pickup height etc. if it wasn't for the 75 tank. Might be easire to just drill the hole at the bottom and be done with it. Thanx for the other good info. also :drink:
Click to expand...

I wonder if they changed the pickup location when going to those bladder tanks/the liners.....never got into that aspect of them....:sos:
 
From what I've read, and this is just hearsay, after a certain year, gas tanks had to have a pick up from the top. A pick up mounted in the bottom is considered a safety hazard, hence the '75 being at the top. Obviously if this is true, it was between '72 and '75 with the switch to a top mounted pick up. The bladder in the '75 and later tanks was also a safety move.
As far as a drop in pump, no such thing for our tank that I'm aware. I was looking into a simple kit from vetteworks that allows the installation of an Fbody pump into an early C3 tank. This option has a lot of advantages, however, about 6" of flat space is needed on top of the tank. No such thing in a '75 tank. I have not spoken to Dan at vetteworks yet about it, because he wasn't sure if it would work for a '75 either and wanted to talk about it. I haven't pursued it much because I figured I would cross that bridge when I came to it. The fuel system isn't my top priority at the moment.

As far as over-engineering your fuel system, yeah, haha, you really can get wrapped in. Like Gene said, keep focus on what you want to accomplish. I know the LS1 won't require any crazy fuel systems as it will be run for now, but when I redo (N/A or T/C) the LS1 the power goal is 550hp to 650hp. I will have a fuel issue then using the stock pick up and such. The question for me is do I build the fuel system for now or then? Could I build it for now and have it easily upgraded for then or do I have to tear it all out? My goal is to have a reliable system, but not overdone to the point of excessiveness for the application, nor do I want to throw money away on a system that will be obsolete when the engine upgrades come. That is why I, personally, am looking into so many options. If I was keeping the LS1 stock I would do something similar to Gene and call it a day. Done deal.
 
Yeh, I hear you man, course you could just keep in mind that it's a continuing project, like my attitude, over the last 15 years this car has changed personalities and composition so many times, it's a joke.....course in that time frame there are SO many options opened up too, hell, they don't even MAKE a SBC anymore that I know of.....unless Mexico maybe??.....

and yes If I had the money and desire I would be into a LS engine at some elevated HP for sure....lets just refer to it as a 'rolling test lab'.....
:lol::trumpet::friends:
 
Why couldn't you replace the tank with one from a 72 that already has the bottom feed point? I be it would bolt right up in the chassis, then all you have to do is plumb it in. Well as I write this maybe not so easy......fuel gage stuff would be different.

Edlebrock sells a kit to retrofit the GM TBI fuel pump to the Edlebrock MPFI system that drops in the tank from the top p/n 3581. It would be a miracle if the flanges was the same.
 
mrvette said:
Yeh, I hear you man, course you could just keep in mind that it's a continuing project, like my attitude, over the last 15 years this car has changed personalities and composition so many times, it's a joke.....course in that time frame there are SO many options opened up too, hell, they don't even MAKE a SBC anymore that I know of.....unless Mexico maybe??.....

and yes If I had the money and desire I would be into a LS engine at some elevated HP for sure....lets just refer to it as a 'rolling test lab'.....
:lol::trumpet::friends:
Click to expand...

I envision my '75 being that way. My future mother in law thought after the engine swap the car would be done. I laughed pretty hard until I realized she wasn't joking. I'm glad she likes me! :clobbered:

TopGunn said:
Why couldn't you replace the tank with one from a 72 that already has the bottom feed point? I be it would bolt right up in the chassis, then all you have to do is plumb it in. Well as I write this maybe not so easy......fuel gage stuff would be different.

Edlebrock sells a kit to retrofit the GM TBI fuel pump to the Edlebrock MPFI system that drops in the tank from the top p/n 3581. It would be a miracle if the flanges was the same.
Click to expand...

I have considered going with an earlier tank, but not for the bottom pick up. I figured If I went with an ealier tank I could surely install the Fbody pump into the tank. It has been done. But what keeps me hesitant of that is cost. New tank + new pick up (for the float and overrated hole plug) + vetteworks kit + pump = a decent amount. But you're right, one could do that and isn't out of the running yet. I'm just trying to keep it to my tank if I can.

I think we need to hash out a few things about what to keep in mind concerning your tank and EFI:

-Keep the pump intake fully submerged in fuel and do not want air getting in
Solution: sump or baffle the tank or buy a tank with either. There's also some foams that can be used that you find in fuel cells. If either are not an option, or it's out of the budget, keep a minimum of 1/2 tank of fuel in the tank at all times (this is what you do, correct Gene?) A plus to the Fbody pump is the whole unit is self regulating (if plumbed correctly), has a 'bowl' internal to the unit (pumps fuel to the 'bowl' where the pump intake is, then from the bowl to the fuel line).

-Inline pumps like positive suction so an intake from the bottom of the tank is the best for this.
Solution: A sump once again or use a tank with a pick up at the bottom. Even though a '75 pick up is ultimately at the bottom, the "U" shape pattern the fuel path has to go (from the bottom of the tank, to the top out of the tank, back down to the pump) apparently can really wear out inline pumps. This is not a concern for intank pumps.

-Pumps like to be cool. Heat kills them.
Solution: Intank mount so the fuel can act as a cooling medium or plenty of air flow for the inline pump.

One could argue Many things about fuel tank, pump location, etc, but one thing I've noticed is most, if not all, OEM's mount their pumps in the tank. There are many benefits to it, and this is why I feel is my strongest option. I plan on either modding the stock '75 sending unit for intank pump mounting or somehow getting a Fbody pump in. The great thing about using an Fbody pump is you open yourself up to the Fbody aftermarket. Lots of those guys do some heavy duty stuff to their engines and there are options I can take advantage of in the future when I build my power.
One thing that needs to be mentioned: When installing the Fbody pump, vetteworks didn't utilize the float. They instead stuck to the original tank's float system. However, it may be possible to use the Fbody float system because they are 0-90ohm/empty-full sending units just like ours. Just need to calibrate the float (read: bend it up to read correctly). This just may be the ticket for our '75 tanks. The only flat spot is the sending unit, so maybe it can be placed in there and not interfere with the filler neck. This is another option I'm toying with. So many ways...so little time.
 
greg75vette said:
mrvette said:
Yeh, I hear you man, course you could just keep in mind that it's a continuing project, like my attitude, over the last 15 years this car has changed personalities and composition so many times, it's a joke.....course in that time frame there are SO many options opened up too, hell, they don't even MAKE a SBC anymore that I know of.....unless Mexico maybe??.....

and yes If I had the money and desire I would be into a LS engine at some elevated HP for sure....lets just refer to it as a 'rolling test lab'.....
:lol::trumpet::friends:
Click to expand...

I envision my '75 being that way. My future mother in law thought after the engine swap the car would be done. I laughed pretty hard until I realized she wasn't joking. I'm glad she likes me! :clobbered:

TopGunn said:
Why couldn't you replace the tank with one from a 72 that already has the bottom feed point? I be it would bolt right up in the chassis, then all you have to do is plumb it in. Well as I write this maybe not so easy......fuel gage stuff would be different.

Edlebrock sells a kit to retrofit the GM TBI fuel pump to the Edlebrock MPFI system that drops in the tank from the top p/n 3581. It would be a miracle if the flanges was the same.
Click to expand...

I have considered going with an earlier tank, but not for the bottom pick up. I figured If I went with an ealier tank I could surely install the Fbody pump into the tank. It has been done. But what keeps me hesitant of that is cost. New tank + new pick up (for the float and overrated hole plug) + vetteworks kit + pump = a decent amount. But you're right, one could do that and isn't out of the running yet. I'm just trying to keep it to my tank if I can.

I think we need to hash out a few things about what to keep in mind concerning your tank and EFI:

-Keep the pump intake fully submerged in fuel and do not want air getting in
Solution: sump or baffle the tank or buy a tank with either. There's also some foams that can be used that you find in fuel cells. If either are not an option, or it's out of the budget, keep a minimum of 1/2 tank of fuel in the tank at all times (this is what you do, correct Gene?) A plus to the Fbody pump is the whole unit is self regulating (if plumbed correctly), has a 'bowl' internal to the unit (pumps fuel to the 'bowl' where the pump intake is, then from the bowl to the fuel line).

-Inline pumps like positive suction so an intake from the bottom of the tank is the best for this.
Solution: A sump once again or use a tank with a pick up at the bottom. Even though a '75 pick up is ultimately at the bottom, the "U" shape pattern the fuel path has to go (from the bottom of the tank, to the top out of the tank, back down to the pump) apparently can really wear out inline pumps. This is not a concern for intank pumps.

-Pumps like to be cool. Heat kills them.
Solution: Intank mount so the fuel can act as a cooling medium or plenty of air flow for the inline pump.

One could argue Many things about fuel tank, pump location, etc, but one thing I've noticed is most, if not all, OEM's mount their pumps in the tank. There are many benefits to it, and this is why I feel is my strongest option. I plan on either modding the stock '75 sending unit for intank pump mounting or somehow getting a Fbody pump in. The great thing about using an Fbody pump is you open yourself up to the Fbody aftermarket. Lots of those guys do some heavy duty stuff to their engines and there are options I can take advantage of in the future when I build my power.
One thing that needs to be mentioned: When installing the Fbody pump, vetteworks didn't utilize the float. They instead stuck to the original tank's float system. However, it may be possible to use the Fbody float system because they are 0-90ohm/empty-full sending units just like ours. Just need to calibrate the float (read: bend it up to read correctly). This just may be the ticket for our '75 tanks. The only flat spot is the sending unit, so maybe it can be placed in there and not interfere with the filler neck. This is another option I'm toying with. So many ways...so little time.
Click to expand...

My '72 assy still has the pipe going to nearly the top of the tank, then U bend down to the pickup sock....and it supports the sending unit float in that travel....and once that line is primed, it don't matter to the pump at all, the gravity going down and out is still greater than going UP.....

I lost the info on exactly what pump I been using, I want to say it's a Walbro ...it's about 1.5" diameter and 6" long....80 bux at Auto Zone some time ago....the original I had from Wash DC area, failed some years ago....but this one been in there for a long time....best I can get out of it is 65 psi with a blocked return line....I have a adj. FPR, so I can jack it around as needed...they only 24 lbs injectors....but I only doing <400 hp....

I THINK the primary reason they do the in tank pumps is for assy ease on the line, it's a complete assy that way, plug and play....ONE hose instead oa 1/2 dozen....etc....

I know nothing of F body pumps and/or tank mods....I kept it simple....something I can DO....I have fucked around with regulator placement and tons of other shit due primarily to a very devious water in gas problem, where I had a gallon or so of water in the tank bottom, it managed to suck just enough water to completely fuck the idle, and leave me crazy....

until I ran it outta gas, and found the culprit here at home....

got some good injectors the engine seems to like much better, and better hoses, and a locking gas cap, car seems fine now for many a month....
:bounce::bounce::cussing: it was a dirty rat to finally kill though....
:surrender::eek::cussing:
 
Gene, I completely agree with you. I deal with water a lot in pipes and all that matters most of the time is where the in and the out are with a pipe, not in between. In fact, as long as the pump is below the tank, and once the tube is primed, it should be a positive suction head on the pump. However, there are practical limits. If the pressure in the pipe drops too low (most likely at the top of the "U"), the liquid will flash to vapor and cause all sorts of problems including dropping prime and potentially cavitating the pump. Since the vapor pressure of gasoline is higher than water, this can happen more easily with gasoline. I'm not sure if this is what is wearing the pumps out or not, but I wouldn't discount it.
I also thought you cut off the pick up tube that ran in the interior of your tank and stuck a sock on the new end. At least that is what I thought you wrote.
Regardless, I won't be chancing it mostly because of my future power goals.
 
Update

I figured I would do a little thread revival and give an update:

Looks like the strongest possibility for me is using the Fbody pump into a stock tank. I believe it to be the simplest solution without loosing too much 'future-proofing'.

There's a large enough aftermarket of boosters and mods that I can do later on to support more power. I also get my built in sump since each of the fuel units has its own fuel pump bowl to prevent pump starvation at high cornering loads. Installation is simple and hook ups are even easier.

This was all known before hand, but I was hung up on the potential problem with my tank's stock design. I plan on contacting Dan (the maker of the adapter plates) later on this week to see if my tank can be used. If not, I'll simply buy an earlier tank (found a cheap source of new ones) and sending unit, then modify it accordingly.

I should be making a move on the parts within the month. Thanks again for all of the help.
 
Greg, I think you may be over thinking this, it is really a easy fix. If you prefer a sump which if you run your car low on fuel you will need. You can buy a small one from ATL, they sell one to convert the fuel cell over for FI equipped race cars. I don't know how low you could go without one and effecting fuel starvation.
Anyways to the pump. The walbro 255 will supply you with all the fuel you need. You could easily adapt one into the factory sending unit with plenty of room. You could run it outside of the tank also, but after many times of doing it that way I now prefer them intank. There are a thousand ways to skin a cat, but if you keep it simple, there are less items to break down on you. I would stay away from cheap pumps, but also be leary of the ultra expensive billet aluminum frame mounted pumps. I gave my Dad the same warning and had to go rescue him in Myrtle beach when his big bad Edelbrock pump that was new decided to stop working after filling up for fuel. I don't think I have ever been let down by a Walbro pump, at least not that I can think of right now. Out of curiosity what computer system are you using to run the LS1?
Justin
 
At some point last winter, I cross drilled the stock pickup tube and got rid of the sock in the tank, just a good large filter before the pump, and I also plumbed in a 5 gallon Harbor Freight/China made steel air tank lower and in front, where the spare tire would have been....so 5 gallon extra capacity, and no slosh problems now...the plumbing that finally worked is a bit complicated so if anyone interested, PM or email, as I maybe not see the thread....

:surrender::eek:
 
Justin, I do tend to overcook things like this. I'll be the last to deny that :surrender: However, I feel I made a good choice. I wasn't really interested in putting a sump in my stock tank for a number of reasons. There was also no fuel cell that met the envelope size, minimum capacity I desired and had the filler neck in a good location. I almost did just stick an in-tank walboro pump on my stock sending unit, but I was concerned fuel starvation, as you mentioned. Seems like the consenus I found was don;t go any less than 1/2 a tank, and I would be fine. However, having effectively a 10 gallon tank was out of the question for me.

Ultimately though, I've chosen the Fbody pump (and sending unit) to be used. The modification to the system is minimal, it's self regulating, there's a wide aftermarket for replacement parts (I could fit a walboro in the Fbody unit if need be), it's an in-tank pump and has its own fuel bowl effectively creating a sump.
The only drawback would be it would not work with my original '75 tank. However, it will work great for a '74 and I bought a new tank for a great price. All-in-all, I think I am still breaking even (if not saving money) over my other options and I have none of their drawbacks.

As for the computer, I'm using the stock Fbody ECU and harness. I will have it slightly reprogrammed to remove the emissions stuff and a slight remapping for a little more punch, but nothing serious.
 
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