Fuel pickup issue on '73 carbed Z, where to start?

[tommott77]

Have a bit of an issue with fuel starvation with my '73 Z. The car is an older (done more than 20 years ago) 350 sbc swap, so we aren't talking about gobs of fuel pressure here. The car seems to be starving out of fuel before the tank empties. The car starved out yesterday (have a clear fuel filter before the carb which wasn't showing any fuel) and I put a couple of gallons in there and it seemed to be back to normal. I thought it was a bit odd as I had put in a good bit of fuel a month ago last time I drove it. Today I ran it a couple more miles (maybe 10 total miles max since putting 3 gallons in it yesterday) and the car stalled out again, thankfully while pulling out into my driveway. Checked the filter and again it wasn't showing any fuel. Note the the fuel gauge is currently inoperable, but after sticking some PEX piping down the filler tube there definitely is some fuel in the tank. At the very least enough to get me down the road if not substantially more.

 

At first I thought I may have a tank issue or perhaps a leak. I did notice a leak once when I overfilled filling up that I attributed to some bad vent lines or perhaps the filler tube. Now seeing that there is indeed fuel in the tank I may be leaning towards a weak fuel pump on the motor. When I got the car there was some hand written notes that have been passed down from owner to owner over the years and one of the notes, which dates back quite some time, which indicated that the car has run out of fuel once it gets below a half a tank in the past.

 

My question is should I start with the fuel pump which would be a trial and error proposition as the current pump is now functional but may struggle some as the fuel level drops, or should I go ahead and pull the tank out and go through everything on that side of the equation including the sending unit? Another option would be to add another electric fuel pump in line somewhere, though that may be overkill. I seem to recollect that stock Zs ran off an electric fuel pump, I don't see one still installed on the car anywhere.

 

Any advice here would be greatly appreciated.

Edited May 1, 2012 by tommott77

[jasper]

I would drop the tank, and do a full inspection.

Refurbish if needed. Maybe upgrade, do a search on

sumps and baffles.

I would pay particular attention to the fuel pick

up tube. Maybe bent, or the end rusted off, and now short.

May also have rust/pinholes sucking air.