So i have had a 2004 g35 sport 6mt (vortech supercharged) that i've been working on for a while, slowly reviving it from the dead(thank you cleric670, for the help a couple of months ago) (was sitting for 7 years with occasionally oil changes and startups in a carport in a field in Tennessee). I have managed to sort out all of the engine problems myself so far so I am about ready to send it to smog.Because the car hasn't been registered, I didn't want to risk driving it to a gas station-no plates. So if I needed a quick test drive between repairs here in California, I would get my red gas can and use that to fill the car.

I noticed a leak a couple of months ago-after i would fill the car up(from red can) like 20 secs later, the gas would leak from the top of the gas tank.This wasn't when the car was idling or driving and my fuel pressure was always good (have defi fuel pressure gauge). I assumed that there was a hole or leak in my fuel filler hose (thats where most of the gas would leak around). So I made plans to drop the subframe, so I could finally get this car on the road. I decided to kill 2 birds with 1 stone and do the differential nose bushings,diff mount bushing, and subframe mount bushings. I also bought the nismo diff cover. So before i parked the car and removed the subframe i drove, and idled the car long enough to let the gauge drop to empty and waited for the gas light to turn on. So at this point I assume im close to empty, I add 2 gallons- no leak, add another 3 gallons- it starts to leak (same place as before), the source of the leak seemed to be somewhere from the top of the tank, so i popped off the access cover under the rear seats.Sure enough the area around the pump was wet- I also noticed I was missing like 4 of the pump housing screws that mount it to the tank. This is where it gets interesting. Some quick math said I probably had around 5 or 6 gallons in the tank no, I originally suspected a fuel pump housing gasket failure, so i removed the 3 screws that were holding it down, the pump bobs up and i look. The tank is full to the brim. The car was level, but there was so much fuel, pushing down on the pump assembly pushed more fuel out.

I found a nearby dealership that had the same amount of bolts thats I was missing and replaced those. I connected the quick connect and fuel pump electrical connecter back, put the negative on the terminal without tightening it down and turned the key to on without pushing in the clutch, my defi gauge said something like 55psi at the rail but the gas gauge was still empty with the yellow light. I turned the key off and tried again, this time the gauge went to a line above empty.

Now while this is clearly a fuel sending unit problem, I need some advice. Would it be smart to replace the pump assembly and the fuel sending unit here? Can i replace everything but my good oem pump( the housing) and switch in the pump and the fuel sending unit.
I tested for resistance at the fuel pump housing side between terminals 2 and 5 and got a resistance of 9ohms which is way under the spec of the factory spec at 80ohms(on full), but i got a good reading of 3.13ohms on the driver side sending unit spec 3ohms(on full). Are there any other fuel related things i should replace with my subframe out?

 

solved- the 4 missing bolts were the key, the bolts keep the fuel in the tank so it travels across the middle of the saddle to reach the other side. I re-tested both the pump and level sensor and they were within spec and fuel pressure.