Has anyone on this board attempted it? For those who don't know what the issue is, I'll lay it out briefly.
Many GM fuel sending units (the entire intank assembly) utilize a venturi pump to fill the canister regardless of the amount of gasoline in the tank. The advantage to this setup is that the pump is always cooled by and fully supplied with fuel even when the tank is nearly empty or during vehicle maneuvers.
Stock GTP pumps have a small (1/8"?) barbed fitting on the pump head that supplies fuel via a flexible hose to the venturi pump located in the bottom of the fuel sending unit. Replacement Walbro pumps do not have this fitting, so far as I can tell there have been two attempts to adapt these to our cars:
1. Racetronix sells a rebadged Walbro with a brass fitting installed in the pump head, similar to the OEM unit.
(LS1 model shown)
2. ZZP sells a kit with a brass t-fitting that installs inline with the fuel pump hose.
I can see two issues with the ZZP solution.
1. The Walbro has a check valve in it's outlet nipple, by installing a t-fitting AFTER this point you provide a drainback path that will allow fuel pressure to fall off after the pump stops. This results in longer cranking times on cold start.
2. The ZZP kit uses rubber hoses. Not only do some people have problems with durability using rubber (even fuel injection safe) hoses in the gas tank, but the fuel sending unit is spring loadad to sit against the bottom of the fuel tank and therefore requires a hose that can change in length. This is why the stock pump is attached to a long corrugated hose.
Alright, finally, here is my question. Has anyone attempted to drill and tap, drill and press, or glue a hose barb into the pump head of a standard Walbro 255LPH pump? Drawing pressurized fuel from this location should bypass the two issues I noted above with t-fittings. Exact location, hole depth, and fitting size would be great. If no one has done it, I'll post up with my findings after removing and examining a Walbro.
Here's a thread I found on the J-body forums. There's no reason to drill out a bolt and use that when NPT nipples are readily available, but whatever:
Walbro 255 1/4 fuel Cut FIX.. - Performance Forum - j-body.org - the jbody organization