Problem is often rust gets into fuel pump inlet valves..remove sock in tank and install moroso race stainless mesh filter (85 but worth it) at tank or at pump inlet. Cleaning / boiling or lining tank has never worked for me..lining falls off. Worse mess than before. Filter will prevent rust from getting to pump like sock is supposed to do, but sock is inside of tank if it plugs, often the problem not the solution. New tanks now available are one sure answer. I am hesitant to use common paper gas line filter in inlet line due to restriction, although have done that and seems to work. All pumps hate suction restrictions. Low vapor pressure fuel makes that worse..suction may vaporize fuel if restricted. Cannot pump vapor.
Suggest measure fuel pressure during accel with tee at carb (careful on this, really ) but can be done. If it drops below 3 or so when floored it is fuel supply if not, ??it is carb. Another way I have done is jug on front floor, rubber line to fuel pump inlet, eliminates tank stuff. Can also use temp electric with that setup right to carb. Carter seems good on electric fuel pumps.
I agree ---interested in what you find.
I am also interested in this issue. I am wondering why can’t we test pump fuel delivery by pumping gasoline from the fuel pump into a container and measure the volume over time?
Do we know how much gasoline that pump should deliver in say, 30 seconds? I can imagine doing that would be an easier test
Thanks, Mike Moore
First, many thanks for all of the advice I received last week on this problem!
Okay, still having some problems with fuel delivery on our 300K.
Here is a quick rundown on what we have had done. Carb was cleaned and fitted with a new carb kit. Floats were set at 23/32 spec?
Items replaced: Fuel pump, fuel pump push rod, fuel filter and all rubber fuel lines.
Fuel tank was removed and sending unit inspected. Blew out fuel lines.
After all of this we still are starving for fuel when the 4barrel kicks in. Also a little harder to start and (at times) some throttle hesitation on normal acceleration.
One question the mechanic had was the engine rebuilt with bored cylinders etc and needs a higher CFM carb. I do not have any history on the engine other then it has been rebuilt.
Any help will be much appreciated! Mark
Arthur L. Davis Publishing Agency, Inc.
ph. 800-626-4081 ext. 1303 cell 319-240-8083
Let's assume the problem is not with the carb.
There are 3 pieces of "rubber" fuel line in the system.
If they are old, they need to be replaced to
ensure you aren't drawing air into the system through an
age crack in the old hose, or perhaps a blockage in the hose.
One is at the fuel tank, connects the sender to the pipe.
One is in the area of the front passenger foot well, connects
the pipe to the next pipe.
The other is from that pipe to the fuel pump inlet.
It is a pretty easy job to replace these pieces with new line.
I think the diameter is 5/16".
It could be the problem is with the fuel sock on the sending unit. If
the tank has rust in it, the sock will plug. While it isn't a terrible job to
get the sending unit out, it takes a while.
If you suspect the sock, but would rather not get into the sending unit,
you could try running the car from an aux fuel tank. Run a long
piece of fuel hose from the fuel pump inlet to an aux tank which
you could place in the pass front seat. Have someone hold the aux tank
so you don't get spills. If the carb performs off the aux tank system, you
know where your fuel restriction is (or isn't).
Posted by: "John Grady" <jkg@xxxxxxxxxxxxxxxxx>
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