[dv657172]

72 GTO, basically stock

Car was idling in garage and just stopped. Was able to get car running again but only after re-filling float bowl and only until bowl empty.

Replaced fuel pump (Ames N128RC) and rubber lines going into pump, didnt fix the problem

Tried running car off external fuel tank, didnt fix the problem (should have done this before replacing pump)

Rebuilt Quadrajet with kit from Cliff R.
Car will still only run off fuel in float bowl for about 10-15 seconds then dies

Engine was rebuilt many, many years ago but only about 1,000 miles on it since then

SS fuel line from pump to carb looks fine with no leaks....could there be an issue with the fuel eccentric or am I missing something else?

[steve25]

Its process of elimination time!

Pull the carb , remove the air horn and confirm that the float or the needle is not hanging up.

Today fuel turns to gummy crap really fast!

[dv657172]

My apologies, I guess I wasnt clear

I just pulled the carb and rebuilt it and put a new pump on it also in trying to find the issue. Unfortunately I am running out of ideas. Can a fuel pump eccentric go bad somehow?

[steve25]

When you installed the new pump did you feel the arm load in and load up under the pump eccentric ?

How did the arm on the old pump look if that looked ok then I would have to say that you need to drop the tank and check to see if the filter sock has collapsed or if it’s just plain clogged off.

Before going thru this dropping of the tank if you have a air compressor take the fuel cap off the tank and blow air back Thru the line from the pump.

Have someone listen at the tank filler neck for air going into the tank.

Also be ready for a rush of fuel coming back out at you once you stop the air if the sock was blocked off .

[dv657172]

Thanks for the ideas

I attached a pic of the armature wear on the old pump. I thought the armature on the new pump had a small load on it although it wasnt too hard to put in. I have only done a few over the years but successfully...at least so far

I guess I will try to run car off an exterior gas tank again and if that doesnt work I would assume its not a tank issue. If it does run off the exterior tank than I will try the tank ideas.

I thought you could replace the sock without dropping the tank or is that for earlier models or not at all?

[steve25]

That’s strange ware on that arm, kinda like the eccentric is warn weird or is wobbling, I mean there’s no sign of any center ware.
Anyway try running it off a gas can .

[indymanjoe]

could you just hook up a rubber hose to where the fuel line goes into the carb? then have someone crank the engine to see if fuel comes out into a can of course.

[Greg Reid]

I had the fuel pump eccentric loosen on a Dodge truck one time. It took weeks for me to find the problem. It was intermittent. It would only act up in the afternoon on my way home from work, never in the morning on my way in. After weeks of troubleshooting when the truck finally just refused to start I was able to verify that the brand new pump wasn't pumping fuel very much at all. When I actuated the pump by hand it shot fuel six feet. I suspect that the eccentric mounting bolt had loosened and it was spinning on the camshaft?
I never went into the timing cover. I blocked off the fuel pump opening and installed an electric pump.

[65 Lamnas]

Originally Posted by indymanjoe

could you just hook up a rubber hose to where the fuel line goes into the carb? then have someone crank the engine to see if fuel comes out into a can of course.

This ^^^

[dv657172]

Rather than try to run the engine off an exterior tank I will just run the line from the pump to a jug and run engine off the float bowl to hopefully pinpoint if its a pump or pump related issue

2 questions

How much fuel should go into the jug if the car only runs for about 10 seconds (stock fuel pump)?

Is it about right for the engine to run off the float bowl for only about 10 seconds before dieing when the float bowl is not being refilled?

[jhein]

Fuel filter installed the right orientation?

[steve25]

The above is a much overlooked point!

If you installed a paper filter the wrong way then the anti-drain back valve will not allow fuel in.

[dv657172]

As far as I know it is....but worth double checking. Which way is correct to be sure?

I thought they could only go in one way, at least according to the service manual.

[jhein]

Spring goes in first, then the filter with the "closed" end facing the carb, "open" end facing the fuel line.

[Greg Reid]

Originally Posted by dv657172

Rather than try to run the engine off an exterior tank I will just run the line from the pump to a jug and run engine off the float bowl to hopefully pinpoint if its a pump or pump related issue

2 questions

How much fuel should go into the jug if the car only runs for about 10 seconds (stock fuel pump)?

A lot. You shouldn't even have to run the engine. Turning the starter should produce a strong stream. Like in my experience above, just pumping it with my hand shot a stream of fuel out. That's how I knew my eccentric wasn't working. It only dribbled out when turning the starter.
I would say 10-15 seconds to empty the bowl isn't out of line.

[dv657172]

Some progress....

I did put the filter in correctly as the car ran today off an exterior tank for about 15 minutes which it wouldnt do previously even after I had replaced the fuel pump.

So I assume there was was a carb (float or needle/ seat) issue which got resolved with the carb rebuild I did after I had already replaced the fuel pump.

However as mentioned earlier it wouldnt run yesterday off the cars fuel tank so I will try Steve's idea on blowing air through line and seeing if sock is plugged before hooking fuel line back up to the tank. Its never straightforward....

Appreciate all the help and advice, will keep you updated

[Tom Vaught]

I had a sock failure on my78 Trans Am one time on a trip to Denver.

Jacked the vehicle up with the vehicle jack, removed the fuel sock (melted shut from bad
racing gas) and reinstalled the pick-up.

Engine fired right up and we drove another 1500 miles on the trip without an issue.

Bad gas caused the melted fuel sock.

TV

[dv657172]

Sure couldnt afford to go 1500 miles on racing gas nowdays at $10 gallon, lol

[dv657172]

Old cars sure keep things interesting. As stated earlier, car ran off external fuel tank fine. Blew air through fuel line to tank and heard air right away at the tank. Hooked fuel line back up and it ran fine for 15 minutes or so with no issue until I shut it off. Still not completely sure if issue was carb (probably), fuel pump, fuel tank pickup blockage or some combination.

I will say I was surprised at how much fuel the car used sitting at an idle for about 15 miuntes when I was running off the external tank, about 1.25 gallons

[steve25]

1 1/4 gallon in 15 minutes at under 800 rpm and no load!

Somethings not right with that.

I know you said you put a new pump in, but please pull your dip stick and see if it smells like gas.