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> Blowing bubbles
emerygt350
post Apr 29 2026, 04:05 PM
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I know it's click bait but whatever. So gradually working through the starting issues on my 73 djet 2.0. is anyone aware of a bubble blowing condition that doesn't require vapor lock? Is there something that can go wrong with a stock 73 fuel pump that would cause it to blow audible bubbles into the tank? This only happens after I have driven it, but doesn't require it to be hot n hot. If I turn the key to the on position and the fuel pump starts I can hear bubbles coming into the tank (even when the tank is full). This is at 40 degrees ambient. This is the real kicker, this will continue after the point at which the fuel pump cuts because the engine is not running. However , when I turn the key off, even after the pump has stopped , the bubbles will stop. ????? When this happens I have a difficult time starting, but it really smells and feels like a rich condition, not what I know from vapor lock. Under true valor lock I can't hear the pump at all.

After I get the engine to catch, normally only a few tries, it stumbles a little then immediately runs great
I think there are two separate problems here, but perhaps not. It's the bubbles that gave me stumped. How could I get bubbles without vapor lock?
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BillC
post Apr 29 2026, 04:09 PM
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Are you sure they are bubbles?

What is the fuel level in the tank? If it's really low, maybe you are hearing splashing from the fuel being returned to the tank.

Maybe you can have someone try cranking the engine while you look down the filler with a flashlight?
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76-914
post Apr 29 2026, 04:25 PM
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Sounds to me like cavitation. See if your intake line is kinked or has an obstruction.
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emerygt350
post Apr 29 2026, 05:01 PM
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QUOTE(BillC @ Apr 29 2026, 04:09 PM) *

Are you sure they are bubbles?

What is the fuel level in the tank? If it's really low, maybe you are hearing splashing from the fuel being returned to the tank.

Maybe you can have someone try cranking the engine while you look down the filler with a flashlight?

Yeah, bubbles, full tank. No mistaking it.

Nothing has changed in the system but I am going to look through everything as soon as it stops raining.

I should mention as well that I had no such problem last year before its long winter sleep but I was noticing what I thought was some pretty poor gas mileage but that turned out to be.a broken thermostat cable. Wrong side of the engine for messing with the fuel lines.
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emerygt350
post Apr 29 2026, 05:13 PM
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Dbl post
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Literati914
post Apr 29 2026, 05:34 PM
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I've heard of the internal sock getting clogged and causing similar noises when the fuel is run low, just a thought.
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