1981 EFI Conversion
 

Hello


Need some advice. I recently installed a Fitech fuel injection on the vette. I tried using their fuel command center and it would constantly overheat. So I want to switch to either an external or preferrably an in tank electric pump. I know the 82 had an in tank electric pump so first question is will the 1982 sending unit direct bolt into a 1981. If so I know the stock 82 pump won't work because I need around 58psi, but couldn't I put an aftermarket pump in place of the stock one? If so what pump do you recommend and if possible and you have some experience what part number for the pump, so I know it will fit and work. Also would the pump have some sort of baffling to keep it from fuel starvation when cornering with a lower level of fuel? Lastly I'm pretty sure the fuel out tube on the sending unit is 3/8. I think at least on my 81 the return line is 1/4 and the vent is 5/16. Assuming the same sizes hold true for the 82 can I use the 5/16 fuel vent as the return instead of the 1/4 inch?

If you know how best to do this, would you consider selling me the 82 sending unit and the aftermarket pump and assemble it for me and wire it so all I have to do is drop in tank then plumb the outside to the efi unit? If so how much? Any help would be greatly appreciated here, as I'm at my wits end trying to get constant fuel, without overheating and dead heading it to just drive 30 miles in the Texas summer. Thanks for your help in advance.

Sender will work.

Get a good port injection pump. It will fit the sender fine.

Holley had a HydraMat that will plug right into the bottom of the. Pump. It will keep it from starving on corners.

The FCC stops fuel flow from the mechanical pump when it's full. That is likely contributing to the overheating. You could gut that system out of it so the fuel can freely flow back to the tank via the vent line connection. Run the vent line off the FCC to the stock fuel pump return line. Block off the return fitting on the mechanical pump. If you think the circulating flow is too high you just put a restriction in the return line.

There are also tanks on eBay that can be used like the FCC but would allow the fuel to circulate to the tank which should stop the overheating.

the 82 fuel pump assembly should bolt right in .you need a fuel pump that is the correct psi for your injection.should go right in place .the wireing is two wires.the hydramat is a good idea.my car does not have it nor does it have any splash baffling.
https://cimg0.ibsrv.net/gimg/www.cor...2a131ab8fc.png

Thanks for responses so far. I've already tried the mods to the FCC but it did not correct the problem. Fitech support says that mounting the FCC by the fender vent in a C3, which is only place I can find the room, puts it too close to the headers so mod won't work. Do you guys agree the 5/16 vent on the sender can be used as the return as the stock return is only 1/4 and I think too small.

I would try it .

I know from a post I saw somewhere, not here, that one guy mounted the FCC in the bracket for the vapor canister. Not sure how close that would put it to your headers. Not that you would be inclined to change, but are your headers ceramic coated. I mainly ask as I am planning for a Fitech in my '80 and planned also to put in ceramic coated headers. If you're using ceramic coating and still having an issue, then I may rethink things.

I'd keep researching. I saw a few other threads where the solution was to install an in-tank pump, and a regulator on the frame-rail near where the stock fuel pump is now. You need a beefier return line, but that solution seems to keep the pump cool (in the tank), and eliminate the fuel center.

Well, no rush, but good to know. I'd be all for reducing the cost of the upgrade.

Fuel Injection Setup
 

Texasthall - check my thread here for info on fuel system parts needed to install an FI system:
https://www.corvetteforum.com/forums...s-of-pics.html

I used a fuel sender from an 82 that you can buy new On eBay for $100. EP241 fuel pump designed for TPI systems. Fuel filter mounted on frame by passenger power control arm. Bigger fuel lines that I sourced from a Caprice, but new ones can be fabbed up. No baffles in my fuel tank, I haven't had problems but make sure there is always fuel in the tank.

I am just west of Austin in case you are near enough by to want to check it out in person.

So, you're overheating the fuel in the main tank too?

The 5/16" return might work, but then it might not. For the best chance at success, I'd run 3/8 line back to the sender so you only have the 5/16" size at the sender.

Great suggestions all. So here are some things I've learned. Regarding the vapor canister location...that's where mine was mounted. Yes headers ceramic coated. Don't need regulator because fitech go street 400 has one built into unit. I'm going to put in an 82:sender and will have a radiator shop put in a 3/8 for return where current one is 1/4. Fitech has agreed once returned they will swap for an in tank pump they have made by a known supplier. They will supply connectors and hoses once they establish the units condition returned. I will remove and block off existing mechanical pump. Plumb it up and hopefully be back in business. FyI their tank pump comes with a mat that works llike the holley suggested earlier for eliminating fuel slosh issue. The mat they have is 3" x 12" should work out ok if all goes right. I can honestly say though that the fitech performance when it has fuel has been remarkable compared to the holley 750 that was on it. From first start it fired and gets better as driven and learns. So for C3 folks in a warm climate go in tank and forget FCC but the injection unit is great. Once I put together in a couple weeks or so we shall see if I feel the same way. Btw I'm near Dallas.

I bought mine from rockauto.com

saw this on another forum where a users was having issues.

Did this. Did not help

Don't know if you have headers or not but according to fitech if a c3, with modified motor and headers, and FCC located where old charcoal canister was, most likely the mod will not work because that vent tends to want to extract header heat through it thus no way to keep FCC cool enough. My experience seems to support this opinion. Assuming my plan for an intank pump works it will cost no more and most likely less than FCC. Just waiting for parts to come in. The

Thanks for keeping us updated! I've been following these EFI threads, and hope to get a Fitech in a year or two, for one or both Vettes. This thread helps to confirm what I thought about the FCC. Hopefully the in-tank solution works.

The 82 sender will get you there, but you'll need to run a bigger return line as mentioned and keep your fuel level high.

I chose to go with a new 78-82 tank, 78-81 sending unit and an Aeromotive Phantom setup as I did not want to risk it without some kind of baffle setup. I will autocross and drag race the car, and I know these tanks will uncover the fuel pump in hard cornering at around 3/8 tank when autocrossing on street tires.