Fuel Problems


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By Oldzcool - 14 Years Ago
Hi All, I have a fuel problem on my stock 272.

She runs good but stops pumping fuel after a short time.

I blew out all the lines from the pump back to the tank ....all clear.

I fitted an in-line filter just before the pump.

I cleant the carb which seemed to be very clean.

Still the fuel is not pumping to the carb as it should.

So I presumed it was a faulty mechanical fuel pump so I bought a new one from Macs.The one that I presumed was faulty was only 3 years old.

After fitting the new pump it is still doing this crazy thing.

Any thoughts ?

Cheers

Oldzcool
By Hoosier Hurricane - 14 Years Ago
Try driving it with the fuel cap off.  Maybe the vent is clogged. 
By shakey pete - 14 Years Ago
maybe its sucking air instead of  fuel  loose fitting  or bad connection or cracked fuel line how much fuel in the tank add a gallon or so more and see if it rrun,s longer maybe pick up tube in the tank is cracked or broken  just athought Shakey Pete disconnect  fuel line from the suction side of fuel pump put rubber fuel on the pump and into a gas can an see if it runs longerSmile
By YellowWing - 14 Years Ago
I would use a vacuum gauge to check the vacuum reading on the input side of the fuel pump, install it with a clear piece of hose. The hose will allow you to see any air bubbles in the incoming fuel indicating an air leak from a possible cracked pickup as already discussed. Vacuum should be very low, less than 1 inch. If it is higher (due to clogged pickup, pinched hose) it will lower the boiling point of the fuel so that as when engine compartment warms the fuel in the lines will vaporize. This will also be visible in the clear line.
By aussiebill - 14 Years Ago
Oldzcool (1/30/2011)
Hi All, I have a fuel problem on my stock 272.
She runs good but stops pumping fuel after a short time.
I blew out all the lines from the pump back to the tank ....all clear.
I fitted an in-line filter just before the pump.
I cleant the carb which seemed to be very clean.
Still the fuel is not pumping to the carb as it should.
So I presumed it was a faulty mechanical fuel pump so I bought a new one from Macs.The one that I presumed was faulty was only 3 years old.
After fitting the new pump it is still doing this crazy thing.
Any thoughts ?
Cheers
Oldzcool

You should check the flexable fuel line at frame to the pump, if still original? they often sucked air, yet never leaked fuel. regards billSmile

By Ted - 14 Years Ago

Just as Bill says, I had a ’54 Crestline that was sucking air at a crack in the flared end of the steel line where the flexible line for the fuel pump attaches.  That problem took awhile to find as it was very intermittent.  Might go 3 weeks without a problem and then might show up a couple times in a single day.

 

On my ’55 Customline the fuel line was cracked just inside the fuel tank where the steel fuel line connects to the inside bulk head of the tank.  That particular problem only showed up when the tank was ½ full or less.  This one also took a while to find as it was in the tank itself.

By jonnireb - 14 Years Ago
If the problem is intermittent there could be something drifting about in the tank.

I had a friend with such a problem some years back. It turned out to be a leaf that

one of his kids dropped into the tank. It would drift about until it came near the fuel

line and would be sucked to the outlet stopping fuel flow.  The engine would die,thefuel

pump would stop, and the leaf being freed from suction would drift on and the engine

would then start. The problem would repeat at random intervals.

By shakey pete - 14 Years Ago
just 1 more thought I,ve found a rubber gas line once that seperated on the in side and created a flap that blocked fuel  going to  the pump acted the same way  Shakey Pete
By Oldzcool - 14 Years Ago
Hi, you guys are awsome......thanks heaps.

Can you check the internal pickup pipe without splitting the tank ?

Cheers oldzcool
By Ted - 14 Years Ago
Oldzcool (1/31/2011)
Can you check the internal pickup pipe without splitting the tank ?
If the fuel line has been repeatedly blown out with air pressure from the engine end back to the tank without the fuel cap being removed, then the tank may have been distorted enough from air pressure to have cracked or broken the interior fuel tank line.  Removing the fuel gauge sending unit from the top of the tank will allow you to shine a light at the fuel line which may or may not help spot a problem with that section of line.  Another option while the sending unit is out is to put a light stream of air into the tank at the disconnected fuel line port and look for bubbles.  This means the fuel level has to be above the line that’s within the tank.  On the '54-56 cars, the fuel sending unit can be accessed through the trunk floor without removing the fuel tank.