Cost to modify gas tank for internal fuel pump

[denniswagnerusa]

I'm getting an estimate of $450 to modify the gas tank to accept the new fuel pump assembly and possibly move the sending unit. This does not include the cost of the pump, pump assembly, or the sending unit. This seems excessive. Am I right?

[mraitch]

Can't exactly answer - but I had my filler neck moved 7 inches and the hole filled up - v. nicely I thought for $75 in Van Nuys

[spriso]

We charge $500 to build a gas tank... so, it seems right to me!

Michael

[fixitman04]

fuel cell sump, welded to the low point in the tank and an external pump would be significantly less

[spriso]

fuel cell sump, welded to the low point in the tank and an external pump would be significantly less

If you like starvation issues and noisy EFI pumps-- go for it!

Michael

[Kevin Desirello]

Sounds right to me to.

[datsun1500]

Did the pump in this thread not work?

http://www.311s.org/phpBB3/viewtopic.php?f=3&t=18898" onclick="window.open(this.href);return false;

[denniswagnerusa]

Not sure what you are asking. The pump has not been installed yet. Converting to internal pump for SR swap.

[datsun1500]

Not sure what you are asking. The pump has not been installed yet. Converting to internal pump for SR swap.

I got the impression that the pump in that thread was close to a bolt in and didn't need as much modification as the Honda pump.

[Alvin]

I had an external 280zx fuel pump for my SR swap and ran it for years. It was definitely audible, wonky fuel level readings and I had starvation issues on the track. I had a internal pump installed about 4 years ago, Wallbro 255 and I've had no issues on the street or track.

I would recommend the Honda/acura in-tank route, and the 400-500 range sounds reasonable, imho.

[denniswagnerusa]

Thanks for all the replies. Being particularly cheap and having already spent a bundle on this restomod, I was wondering why no one was simply cutting a hole for the fuel pump assembly and dropping it in with no welding and fuss. The fuel pump assembly comes with a rubber gasket which should seal on the flat top of the tank. If the sending unit interferes couldn't it be rotated so the float was out of the way? That would not allow placement of a catch basin in the bottom of the tank. How important is that catch basin anyway? The tank already has baffles that concentrate the gas somewhat in the center. I realize that the pump could become starved for gas with heavy cornering and steep uphills or downhills. I don't plan to race this car and there are no hills in Florida. Wouldn't the catch basin actually be a negative with a low tank and flat straight roads?

[spriso]

Dennis,

Your SR20DE engine requires a much higher fuel pressure than a stock fuel pump-- EFI systems typically run in the 40psi range-- so you need a constant feed of fuel to your injectors-- the excess is returned to the fuel tank to complete the loop.

While there are 2 baffles in the roadster tank, they won't stop starvation when the tank is low on fuel or you are going around a long sweeping bend (when all the fuel sloshes to one side of the tank).

Modern cars (and when I say modern, anything with EFI from the 80s and up) have a fuel catch can built into the tank that the fuel pump sits in. This assures a constant flow of fuel to the EFI fuel pump and the return line on the pump dumps the fuel into the catch can first, and then it overflows to the rest of the tank.

Honda catch cans are a double box, one drains into the other and the fuel sock fits down into the center of the can:



To get the fuel pump to attach to the fuel tank it is best to use the stock mounting ring (cut out of the Honda tank). The mounting flange has a raised ring on it which the gasket for the fuel pump sits on to give a positive surface for the gasket to sit on-- and to prevent leaks.



We re-use the fuel pump catch can and mounting flange from the Honda tank, and relocate the fuel sender so it sits out of the way. Needless it say it is lots of welding on a paper-thin fuel tank and it is critical that there are ZERO leaks (we have our tanks independently inspected) to make sure that they don't leak.



Fuel tanks are very labor intensive-- and not something that should be attempted by just anyone-- DO NOT attempt to weld a gas tank that has not been professionally cleaned-- save this one for the experts.

My .02 yen, spend at will.

Michael

[mraitch]

I think Michael has it covered.

[denniswagnerusa]

Thanks. I guess I will need to bite the bullet on this one.

[bobd]

Is mig welding the gas tank out of the question?