Caddy fuel pump

[Inprimer]

My friend(neighbor) has a 56 Caddy sedan Deville 4 dr HT. He's rebuilt carb ,some wiring etc, basically a good car, we had fuel issues the  other night (always in a parking lot, never at home),the fuel pump seemed to go dead in other words the clear fuel filter was draining back into the fuel pump I'm sure the gas flowed back into the fuel pump, I suspect the diaphragm has a pin hole in it. We poured gas directly into the carb and it fired up, as soon as we got home popped the hood and gas leaked out of the fuel filter... The question is ,is it going back through the pump and back to the fuel line or right into the oil?? We are awaiting for a new pump, should we replace the oil?

[unklian]

Pull the dipstick, and give it a smell.

[wayne petty]

well...

a quality fuel filter before the pump is always a great idea...


catches sediment that is spread thru the fuel system..

magnets in the fuel tank.. or on the bottom of the fuel tank until you or they can get some inside the tank work also..








inside the fuel pump are a pair of check valves and a diaphragm...

you might want to verify that the check valves are just blocked with sediment... installing a few filter directly before the pump inlet.. using something like a ac delco GF61.. inline or i prefer one of the fuel injection type of fuel filters..




you might want to disable the ignition system on a cold motor...   with the new filter installed... disconnect the fuel line at the carb... extend it into a clean clear plastic 2 or 3 liter soda bottle...  start cranking the engine.. i usually advise 15 seconds of cranking while you observe the pulses of fuel from the end of the hose...   this full flow test will SOMETIMES clean the check valves out... it won't fix a bad diaphragm...  

you can test for a bad diaphragm with a hand vacuum pump.. hook it to the carb side of the pump.. pinch off or disconnect and plug the inlet side.. and apply about 15 inches of vacuum.. don't go to as much as you can as the fuel pump never sees that much vacuum... you don't want to tear the diaphragm...

if it holds... then just the check valves are filled with sediment..

since the pump never pulses at full flow... except during this test.. the sediment just settles...

i have also filled the float bowl with some gasoline.. making sure not to spill ...

squeeze off with some long needle nose pilers.. the fuel inlet hose...  get the engine started.. as the float level drops... before the engine stalls.. release the pilers and a big rush of fuel will come up from the tank and right thru the pump...

[Inprimer]

I'd like to thank Wayne Petty and others for the answer, finally got to it and sure enough the pump was perforated, got new pump, 2 new fuel filters  and oil/filter change, thanks for the answer Inprimer and my friend Bill