6mpg, dying with a tank thats half full. Help guys!

[ShakotanLife]

Hey guys,

background on the car: 73, l24 with weber downdrafts, 280 dist. of an unknown year, Timing is at 14 at idle, and an Electric pump at the rear.

Problem: Ill be cruising at freeway speeds(60-75) and the car will just lose fuel delivery. You can hear the carbs sucking in air. IT will buck as it gets the occassional taste of fuel. Ill have to limp my way over to the side of the road. Add fuel with my little 1.5gl gas can. Luckily I have made it to gas station each time. My gas guage doesnt work by the way. On top of that I only get to drive about 40-60 miles each time before this happens. Which means im only getting 6-8mpg. Im trying to get this fuel delivery problem solved before I worry about tuning the carbs.

Ive replaced the front fuel pump, fuel filter, plugs, cleaned the rotor.

So any help on what I should be checking out would be appreciated...

[psdenno]

Have you checked the new fuel filter to make sure it hasn't clogged with tank debris? Have you pulled a fuel line at the carb to make sure gas is getting that far?

Dennis

[ShakotanLife]

the fuel filter is perfect with no clogging that I can see at all. I was wondering if it was common to put a fuel filter before the electric pump in the back? I havent pulled it at the carb while on the side of the road when the car is dying. Ill do that next time it happens.

[JLPurcell]

I would install a fuel gauge and place it in view while driving. This would be my first step to establish fuel delivery. JLP

[FastWoman]

Happened to me in a '75 280, not a 240, but it might be the same problem:

My car was only 10 years old at the time. I would fill up the tank, and by the time I had used approx 1/2 of the tank, I'd be "out of gas" and stranded on the side of the road. I took the car to my mechanic (because I didn't work on cars as much back then and had a really good mechanic -- rare). He found that the siphon tube inside my fuel tank had a rust hole in it. I could draw gas as long as the fuel covered the rust hole. He fixed the problem for very little money. I guess he was able to braze the tube closed through the gas sender hole. I suspect this isn't a common problem, but it *might* be what's happening in your case.

[Gary in NJ]

Floats out of alignment or float valves that are sticking. If nothing else, something to rule out.

[kenz240z]

Open up the electric fuel pump back by the tank and check the filter inside it. Chances are it is clogged.

[Gary in NJ]

Opps...just saw that it's Weber's...forget my useless suggestion.

[ShakotanLife]

Do you guys know If I have to drain the tank to pull the filter out? The tank Is full!

[5thhorsemann]

no to draining the tank to check your filter. You think you have half a tank, but no gauge. Read this http://www.classiczcars.com/forums/showthread.php?42135-Car-won-t-swallow

I just went through a similar issue with only getting a half tank off running out of fuel. Could be your trouble. Drain your tank and start by seeing how much fuel you can get in the tank from jump.

Edited May 30, 2011 by 5thhorsemann

[ShakotanLife]

That was helpfull, Ill check out the vent tubes tomorrow. That seems like a very viable solution. Ill also pull the filter tomorrow and check it.