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Discussion Starter · #1 ·
Hi I have done a search of the forum but haven't found much info in relation to my year Corvette, 81. Correct me if I am wrong but the design of this system change through out the life of the C3s?

I believe my tank has a bladder in it so that rules out cutting a hole in the tank to install an in tank assembly I guess. So I guess I have to use an external pump right?

Did the earlier C3s have the fuel exit from the bottom of the tank instead of through the assembly that is found in my year?

I am interested in how cheap I can pick up an aftermarket fuel tank? I live in Australia though so shipping will probably kill me on that purchase.

Anyway would be good to hear from someone who has done the conversion on an 81 (I think the 80 is pretty much identical as well?)
 

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You should be able to find a used in tank 1982 fuel tank sending unit/fuel pump combination. It should bolt right up to the tank. There are several later model C-4 pumps that may fit into the assembly, like an '85 or '86 pump. The flow and pressure should be fine for up to 450 hp. Look into this option.
 

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you have two options.

get a 82 sending unit, it should drop right into the top of the tank but I am not sure.

Or get a 82 gas tank with the sending unit and install it.

then just take the stock 82 sending unit, get a 4th gen f-body pump and mount it onto the stock sending unit in place of the old pump and your done. The only issue you will have is when you are at less than a 1/4 tank under acceloration you may get some fuel starvation. there are ways to fix that though.

finish it up with a c-5 fuel filter/regulator and your all done.
 

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Discussion Starter · #4 ·
Ok where is a source to get a cheap (even second hand) 82 fuel sender unit? Remember I am in Australia so please don't suggest wreckers.
 

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Ok where is a source to get a cheap (even second hand) 82 fuel sender unit? Remember I am in Australia so please don't suggest wreckers.
Google is your friend here...along with E-bay. There are many Corvette specific salvage yards in the States also. Should be easy finding one.
 

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Discussion Starter · #6 ·
Ok a few of quick questions to wrap this up:

- How much should I expect to pay for the sender unit? ($100?)

- I thought the F-body internal pump was in a big plastic enclosure and included the regulator, etc?

- Do I need to modify the sender fittings?
 

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Discussion Starter · #7 ·
Ok after a bit more research here is what I have come up with for the system:

- Replace sender with 82 sender unit
- Install Walbro 255 fuel pump in 82 sender
- Install C5 regulator/filter

Does this sound like it will work? I am guessing I will need to modify some fittings for this?

Final question:
Could I run the fuel to the engine bay down the old evaporating line on the drivers side and move the canister over to the passenger side in the engine bay? This seems like a good idea since the fuel rail input on the LS1 is on the drivers side of the vehicle. The smaller diameter pipe for the fuel sending won't be an issues? Or has someone done this change before with just a big flexible hose in the engine bay from the passenger side?
 

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Ok after a bit more research here is what I have come up with for the system:

- Replace sender with 82 sender unit
- Install Walbro 255 fuel pump in 82 sender
- Install C5 regulator/filter

Does this sound like it will work? I am guessing I will need to modify some fittings for this?

Final question:
Could I run the fuel to the engine bay down the old evaporating line on the drivers side and move the canister over to the passenger side in the engine bay? This seems like a good idea since the fuel rail input on the LS1 is on the drivers side of the vehicle. The smaller diameter pipe for the fuel sending won't be an issues? Or has someone done this change before with just a big flexible hose in the engine bay from the passenger side?
I'd recommend using a 3/8" fuel line. The evap line is either 1/4" or 5/16", I can't remember which. I have seen installations that have used stainless braided hose running from the regulator to the fuel rail. Just make sure you buy hose that is rated for fuel injection. There is a quick-connect fitting for the fuel rail available that will attach to an AN hose fitting.

You could always use the original 3/8" fuel line on the passenger side and run a flex hose from the original fuel pump fitting end over the transmission and into the fuel rail. There should be adequate room to run the hose away from the exhaust. With the C5 regulator you just need to run a short hose back to the tank. I used the evap line fitting because it was larger than the original return fitting on the 72.

:cheers:

Rick B.
 

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I went for Walbro inline pump: http://www.summitracing.com/parts/VPN-GSL392/ converted to -6 AN fittings (walbro pumps are 10mm fittings, you can buy adaptors)



It would be a nice time to converted to AN

I'm running -6 for feed line and -6 for return line as well + russel fuel filter. -6 AN is good for up to 500 hp setups.
 

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Discussion Starter · #10 · (Edited)
Ok been away a while and was thinking about the fuel system again today.

Do I really need a 82 fuel sender or can I not just modify the current send to have a fuel pump on it? I am guessing I will need to get the pump power wiring out of the tank somehow but that wouldn't be too hard.

Perhaps I should be using an external pump attached to my original sender for simplicity. Or are these too loud?
 

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You will never hear the fuel pump once the engine is running. I have an electric water pump on my engine that starts running before I start the engine and just the gurgling of the water masks any fuel pump noise that might exist. Not even worth worrying about unless you use a pump that is known to be very noisy.

:cheers:

Rick B.
 

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Discussion Starter · #12 ·
Don't know why I had it in my head that I needed a intank pump.

Well the big questions are then:
- What is a good option for a pump? (I won't be modding the engine so just stock fuel pressure and flow is fine)
- Where should I mount the pump? (Do you think on top of the frame rail right next to the tank will be ok?)
- Anyone know a cheap source for the C5 fuel filter/regulator?

Thanks for all the help.
 

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Don't know why I had it in my head that I needed a intank pump.

Well the big questions are then:
- What is a good option for a pump? (I won't be modding the engine so just stock fuel pressure and flow is fine)
- Where should I mount the pump? (Do you think on top of the frame rail right next to the tank will be ok?)
- Anyone know a cheap source for the C5 fuel filter/regulator?

Thanks for all the help.
Here are a couple of pics of the mounting on my car and the layout of the components:





I bought the C5 filter/regulator at NAPA. IIRC it cost ~$45.00 or so.

:cheers:

Rick B.
 

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Discussion Starter · #14 ·
Thanks for the input.

However I live in Australia and I will not be able to get the car road registered here with the fuel system mounted like that. It would have to be somewhere above a frame rail, so there is no line of sight to the road. Also on the 81 the line feeds from the top of the tank not the bottom.

I am assuming that I need to get the pump below where the pickup is in the tank for most reliable operation?

Is that a filter you have before the pump? Do you think I might be able to go without this because I have the filter sock on the bottom of my sender unit?
 

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Thanks for the input.

However I live in Australia and I will not be able to get the car road registered here with the fuel system mounted like that. It would have to be somewhere above a frame rail, so there is no line of sight to the road. Also on the 81 the line feeds from the top of the tank not the bottom.

I am assuming that I need to get the pump below where the pickup is in the tank for most reliable operation?

Is that a filter you have before the pump? Do you think I might be able to go without this because I have the filter sock on the bottom of my sender unit?
Those pics were taken before the body was put back on. You could mount the pump and regulator above the frame rail considering that your fuel pickup is on top of the tank.

The fuel pump sucks fuel from the tank so you will want to mount it as low as legally possible. I have a pre-filter before the fuel pump but you could eliminate that if you want to. Depends on how comfortable you are with the internal condition of your fuel tank.

:cheers:

Rick B.
 

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I used a walbro 255 and C5 filter/regulator (ebay).
I mounted the pump in the passenger side rear frame rail and the filter above it. I routed my fuel line in the original passenger side location. This allows you to keep the spare tire too.
 
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