Fuel Problems

[dkclark]

61 Catalina 2-door 389 Tri-power Auto. With a new gas tank, sender unit and pickup filter sock and electric fuel pump installed, I get "running-out-of-gas" feeling. All carbs have just been rebuilt. The first 20 mins or so all is fine, even when I go through passing fear, the engine takes all I give it. As I travel at 50 mph, the engine cuts out and tries to stall. If I slow to 20 mph, it moves along. Its not electric, just installed a 140 amp alternator, battery is in the trunk w/ negative ground back to engine, not the frame. The fuel pressure shows 7 psi. Any thoughts ?

dkcphoto@swbell.net

[Larry]

My '69 Lemans has too much engine for fuel pump, so also will starve out sometimes if I get on it too much (usually if I've been just sitting idling for a while). It literally sucks the carb too low and the fuel pump must catch up and refill bowl before. But, it does in fact refill if I let up on it and I'm fine again.
Have you tried pulling over when this starving happens, perhaps even shuting down for a couple minutes, then turning power back on (fuel pump should pump up to pressure), and then restarting and trying to go again? If it runs OK again, then it would seem to have perhaps a low float problem (maybe on all all three carbs). Perhaps the fuel pump just can't catch up to refilling the bowls. Sometimes when they rebuild carbs they tend to put the floats pretty low (perhaps to avoid the overflowing/fire situation-- can't blame them).
We are assuming the car straightens out after sitting for awhile, right? Is the tank vent line clear?
Let us know how this progresses.

[Stu Norman]

It sounds to me like you may have some sort of fuel starvation problem. The timing of the event (after 20 minutes) makes me suspect it is heat related, vapor lock from a fuel line being too close to an exhaust pipe.

The second thought that comes to mind (with the tank replacement and all) is that maybe your fuel tank vent is plugged? Easiest way to check that is to drive the car until you feel the loss of power, pull over as fast as you can (SAFELY!) and remove your gas cap. Do not turn off the engine, just get back in and drive a few more miles to see if the problem suddenly cleared up.

[64catdroptop]

Try a new fuel filter. I had the EXACT same problem - replaced the little cartrige fuel filter just as the fuel line enters the carb. Fixed everything.

-r-

[clh11380]

Had a problem similar to what you are experiencing. One of the things that get overlooked is the heat riser. The thermal spring on the riser is missing on my 63 Cat. I was having hot start problems, miss at highway speeds, but would run ok at low speed, or WOT. I replaced the fuel pump with a Carter mechanical unit with about 6.5 PSI, and had replaced the carb with an Edelbrock 650CFM 4bbl. electric choke. What I found was that at higher speed, the heat riser was closing, and forcing exhaust through the intake causing the carb to overheat and boil the fuel out, and at moderate speed would act like fuel starvation. Solved problem by brazing heat riser valve open, and blocking exhaust crossover at intake manifold. The excess heat in the manifold was boiling the fuel out of carb when engine was shut off, causing the hot start problem. With the above fix I solved both the running and hot start problems.

[Stu Norman]

Did this issue ever get resolved?