stock tank w/ls1 swap?
 

Hey guys,

I have a few questions, I'm in the process of swapping over a ls1 from a 01z donor car and was wanting to keep my behind the seat tank. What mods have to be done to the tank in order to do this?

The truck is '70 shortwide btw.

Re: stock tank w/ls1 swap?
 

I have pics of how I modified the sender for a return line on my build thread on ls1tech. Click on the link in my sig. Its on page 2 or 3 I think.
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Re: stock tank w/ls1 swap?
 

AWESOME!

thanks, that was the info I was looking for. You most likely had a regulator on the rail, where as I will need to run my feed out of the tank into a walboro pump then into a filter/regulator combo??

sorry for all the questions, but this whole swap is all new to me.

btw, how loud is the external pump? I've heard they are noisy?

Re: stock tank w/ls1 swap?
 

If you have a returnless fuel rail, then yes, fuel pump to filter/regulator, then return line to tank and feed to engine.

The pump wasn't as loud as some other aftermarket pumps but is louder than an in tank pump, but once the truck was running you couldn't hear it and the truck wasn't super loud it had full exhaust all the way out with flowmasters.
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Re: stock tank w/ls1 swap?
 

I just attached all my lines to the stock tank, nothing special using EFI hose.

Re: stock tank w/ls1 swap?
 

I removed my factory tank and had it cleaned at a radiator shop. While it was there, I had them weld a bung into the tank and ran my retun line into the tank. When the truck is running, you can't hear the fuel spray into the tank. It works good. My tank builds up preasure after running for a while but I haven't had any problems and have put about 5,000 miles on it.

Re: stock tank w/ls1 swap?
 

Thanks for the pics awhite!

I'm starting to get a much better grasp on this fuel stuff, even though
this is just a basic install.

Re: stock tank w/ls1 swap?
 

Would it be possible to weld another bung onto the top part of the tank, or even by the filler neck, then run a line somewhere to the outside of the truck as a vent?

Re: stock tank w/ls1 swap?
 

I have a question for you two guys that have done this already... Have you ever had an issue with the fuel pump cavitating? It seems like that would be an issue using an inline style pump to suck the fuel up a tube and then back down before it even gets to the pump.

Re: stock tank w/ls1 swap?
 

what about fumes? my tank is a emissions tank and has fittings all over it and I put my return line to the one on the filler neck and it works. But I do have gas smell, but i had that carbed or efi. its the problem with having the tank inside.
I am assuming with the emissions style tank there is enough venting going on b/c I do not run into a problem or my gas cap doesnt seal 100% and allows enough venting.

I am using the stock pickup and do not have a problem, or at least I do not think I have a problem, if the system stays primed I do not think there should be an issue.
The only issue I have is that about every 4th key on, the thing will drive fine until you mash it, it down shifts but its lean and will not go any where, I can turn it off and start it back up and all is fine, till the 4th key on. If that was cavitation would it be OK right after turning it off and turning it back on? I think its in the tuning somewhere, which I have went thru several times and can not find anything....

Re: stock tank w/ls1 swap?
 

LS1nova? has the truck you worked on back
in '05 with this setup had any issues?

just trying to make sure this is a good working
setup before I take the plunge
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Re: stock tank w/ls1 swap?
 

Well, I would run a line to the outside of the truck.


Thats weird that it happens at that frequency...

Re: stock tank w/ls1 swap?
 

Not that I'm aware of, but it isn't a daily driver, it gets driven to shows in the summer and I'm sure if Jimmy had any problems with it he would have said something. My blue '72 never gave me any problems either but I didn't drive it that much before I sold it.
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Re: stock tank w/ls1 swap?
 

sounds great. I plan to daily drive this truck for the next year or so at minimum.

Re: stock tank w/ls1 swap?
 

I have only had one issue with my fuel system. I had less than 1/4 tank of fuel and drove through my neighbors property at an angle which had the fuel run to the side of the tank away from the pick-up tube. I was able to restart it after it died and drove off. I now keep it above 1/4 and haven't had any more problems. I've never had a cavitating problem but the way I installed the return line, I belive the fuel sprays against the back side of the tank, not the bottom near the pick-up tube.

Re: stock tank w/ls1 swap?
 

I've wondered this myself but most older fuel injected vehicles have preasure in the tank when you remove the cap. I would rather have the tank outside the vehicle. The reason I used the factory tank was due to the fact that I drive my truck as my regular transportation and my spare tire is under the bed where the tank would have gone. I am going to check into other possibilities later but it works fine as it is so I am leaving it alone for now.

Re: stock tank w/ls1 swap?
 

Would attaching the return line toward the bottom of the tank cause any issues? I just don't want to hear a waterfall behind me.

Secondly, I heard external pumps are not designed to pull thru a pickup tube and they can burn out. On mid to late 80's Ford Bronco's had an external and internal pump. The pump in the tank is a low pressure/high volume pump to get the fuel to the high pressure pump half way up the vehicle which in turn increased the pressure to the engine. I had a 1986 Ford Bronco with fuen injection that ran at 48PSI that had this pump setup with over 145,000 miles. Has anyone came up with a way to implement a low pressure pump in the stock tank to push fuel to the high pressure pump? Thinking this may help extend the life of an external pump.

Kevin C

Re: stock tank w/ls1 swap?
 

Theoretically, you would want the return line end as close to the pickup tube as possible I would think. seems like it would help if the tank was getting low and fuel was sloshing past the pickup, the return line would always be spraying some fuel.....but that's just my opinion.

As far as the external pump being over worked, once the system is "primed", like mentioned earlier, the pump has less work and force to overcome to continue to supply the rail.

just my .02, learned a lot from this thread already...

Re: stock tank w/ls1 swap?
 

you not going to hear a waterfall of fuel....

Re: stock tank w/ls1 swap?
 

Ok, how about welding a bung to the bottom of the tank? That could be a feed to an external pump with the force of gravity. Then use the old pickup tube as a return line.

Re: stock tank w/ls1 swap?
 

run what line to where?
my tank is stock, ie behind the seat, where would you recommend running the line if tank is inside?

Re: stock tank w/ls1 swap?
 

I dont see why that would not work.

Re: stock tank w/ls1 swap?
 

The down side to this is if you got a leak from a broken or rusted line the whole tank would empty out. Also if you ever had to take a line off for any reason you wouldn't have a way of stopping the fuel flow. It would however work way better than siphoning the gas up and out of the tube, gotta pick your poison I guess.
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Re: stock tank w/ls1 swap?
 

Same problem as above if you put a fitting in the tank. Could also raise fuel pressure trying to push fuel into a full tank, by causing a slight restriction. You do want the return to go close to the pick up, but that may only be for intank pumps.
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Re: stock tank w/ls1 swap?
 

If its a '72 I would use the hose that comes out of the passenger side that hooks to the line that goes up into the rear b pillar and back down. Then run it outside where the charcoal canister used to hook to it. Being higher than the tank it would be a fine vent.
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