Bog and stall issues
 

I have a 66 GTO with 389 and Tripower. Lately started having issues with the fuel supply. Runs fine most of the time. Problem starts when I get low on gas. (1/4 tank). Starts to bog down when I accelerate going up hills. Before long it will happen on straight away too. Bogging leads to sputtering and smoking and finally stalls. Fires right back up and idles fine. Press on the accelerator and it stalls again. I can make it to the gas station and fill up. Let it sit a while and it will run okay until the gauge reads low again.

Not sure where to start. Gas tank? Fuel pump?


I had the carbs, sending unit cleaned. The mechanic dropped the fuel tank to look for trash. Didn't see anything to cause concern. It is an old tank. Replaced the fuel filter and the dirty air filters.

Anyone else had this issue or have a suggestion?

This is not a problem due to the Tripower setup. You're obviously running the carbs out of gas, hence the backfire and problem going up hills. It could be the fuel pump, but it sounds like a fuel tank pickup tube location issue (the tube with the sock on it).

A similar situation I had once was due to a tiny crack in the high spot of the steel line over the rear axle. With tank full it didn't leak enough to ever see a spot on the ground. With fuel level lower than that spot, the pump would just pull in air.

Stall and Bog
 

I would check the sock on the fuel pickup in the tank. Debris in tank can accumulate there and, after running a while, stop fuel. When you turn off motor, the debris falls off, only to start the cycle over.

The fuel out there today is hard on the original fuel socks typically that have never been changed in the fuel tanks. Practically any modern fuel sock with the same tube diameter inlet can be used. Actually a pretty easy fix but I would also look at the fuel lines closely, like Mr Gifford mentioned, before I would drop the tank.

Easy enough to remove the hoses on each end, install a plug on one end of the hose and connect it to one end of the fuel line.

Then you pressurize a second hose (with a cheap tire inflater) connected between the inflater and the fuel line for a few seconds and then spray the fuel line with soapy water. If you see bubbles you have a fuel line hole sucking air when you are driving the vehicle with low fuel in the tank. The Fuel Tank is not connected during this test.

Tom V.

Fuel pump