bubbles in 1946 Cadillac fuel bowl

[Glen]

Dave T.

Another thought: What happens to the bubbles you see?  If the bubbles collect in the bowl getting larger until they force most of the fuel out, then they are most likely air.  If they move to the top and the large bubble at the top never seems to get any bigger then the bubbles are fuel vapor.  Now on the pressure side of the pump they condense back to liquid. 

Does that make sense to everybody?

Glen

[Skipper236]

Dave, I have the exact same problem with my 1939 LaSalle. Did you get your situation resolved? Sk

[robert G. smits]

Don't totally rule out the contribution of faulty hose to the air bubbles until you make certain you are using Fuel Injection grade hose (SAE 30R9).  The old hose we used for years (SAE 30R7) is not ethanol resistant and will deteriorate over years of ethanol exposure.  During the 2010 Sentimental tour in Texas I was having vapor lock issues and noticed the air bubbles in the fuel pump.  The electric emergency pump also quit working(again a ethanol problem in a 7 year old pump)  I removed the old pump and installed fuel injection hose and was able to complete the next 4 days of the tour with only mild problems. The same goes for fuel pump diaphragms.  If you rupture your diaphragm and are using an emergency electric pump you will full your crankcase with gasoline.  It is getting to the point that I am considering going to electric only systems on my touring cars.
Bob Smits #2426

[R Sotardi #11719]

In Arizona we have no choice on ethanol it's 10% or nothing. 10% will flash off(boil) in winter at 105F and summer at 145F. With fuel components running at @150 +, you can see the problem. I have been adding 1 qt of kerosene to 10 gal of 87 octane in my Hudson( 50 Caddy has no problem) to avoid vapor lock but I feel it doesn't do much. BUT, sleeving the fuel pump lines, incoming and pump to carb, with mylar  definitely had an effect. I also placed a mylar pad between the fuel pump and the exhaust manifold. This is a concern area on flatheads. You can use a gauge to test for pressure and suction if you think there is an air leak.

[62droptop]

there are comercially avail thero sleeves for fuel lines
the new fuel is crap lilke everyone else is saying
there is a website, puregas.org    i believe that lists gas stations that still have gas with additives like ethanol in them anywhere in north america

the idea if using an electric pump to back up a mechanical pump is not the best idea
most electric pumps do not allow fuel to free flow through them while they are not running
also the pressure from a electric pump may burst the diaphram and fill engine with gasoline

i just replaced a suspect mechanical pump on my 62 cadillac with an electric mounted close to tank outlet as possible,that is where they should be mounted,they push fuel,not suck it
as far as originality is concerned, you can remove pushrod from mechanical pump and leave there for looks,and run a new hidden fuel line to the carb to run the motor
i would rather be running and not original than not be able to use the car  because of vapour lock
to me a car that doesnt work right or has to be babied  is not worth owning.
i was towing a wood chipper behind my cadillac tonight down the highway.i
treat it just like any modern car,i added disc brakes to stop the beast,now electric pump and i use it like a truck to haul anything, anywhere