No fuel flow?

-
JeremyAB95

JeremyAB95

Well-Known Member
Joined
Sep 21, 2016
Messages
118
Reaction score
29
Location
Ohio
I have an issue where after driving a while, the engine will cut out due to fuel starvation. Flowmeter says there's no flow, and nothing coming out in the carb. Took the gas cap off and it hissed pretty violently. Added some gas because we weren't sure that the fuel gauge was working, and maybe it ran out, and it started working again.

My theory is that it may be a plugged vent line creating back-suction in the tank so it can't travel down the fuel lines, and that removing the cap to purge the vacuum was what fixed it.

My friend is thinking it ran out of fuel and that the fuel meter isn't working right, and that adding the gas is what fixed it.

My question is, which is more likely, and would a blocked vent line or lack of vent line create a condition where there's enough vacuum in the tank to keep it from being pulled through the lines by the pump? Or maybe both of us are wrong and it's something else entirely, and there's other areas I need to investigate.
 
Lack of venting... You either don't have enough vent or the vent line is plugged...

Not for long term, but test with gas cap not fully seated and see if it's any better if the you can get some air through the cap... If that works, check your venting...
 
krazykuda said:
Lack of venting... You either don't have enough vent or the vent line is plugged...

Not for long term, but test with gas cap not fully seated and see if it's any better if the you can get some air through the cap... If that works, check your venting...
Click to expand...
I'll try a little experiment with it. Thanks!
 
What year model are we talkin' about here? Up through part of 70 the vent was VERY simple. Some of the 70 cars (mostly CA) and later had evap systems on the tank. If you screw up that system, you can end up without having a vent.

The early vent system could not be simpler. A simple tube going down and ending in the inside of the frame rail. VERY easy for insects to build mud nests, etc and plug that

tankvent.jpg
 
Might be debris in the tank as well. Have you ever had the tank out or installed a new tank?
Debris can get sucked to the tank filter sock as you drive along restricting fuel flow. When you shut the engine off the debris falls off. Once you start the engine up the process starts all over again.
 
mullinax95 said:
Might be debris in the tank as well. Have you ever had the tank out or installed a new tank?
Debris can get sucked to the tank filter sock as you drive along restricting fuel flow. When you shut the engine off the debris falls off. Once you start the engine up the process starts all over again.
Click to expand...
Also some good insight! I will look into this as well if I find no issue with the vent line.
 
67Dart273 said:
What year model are we talkin' about here? Up through part of 70 the vent was VERY simple. Some of the 70 cars (mostly CA) and later had evap systems on the tank. If you screw up that system, you can end up without having a vent.

The early vent system could not be simpler. A simple tube going down and ending in the inside of the frame rail. VERY easy for insects to build mud nests, etc and plug that

View attachment 1715062727
Click to expand...
Car in question is actually my best friend's 69 Nova. My own vehicle is a 70 Duster with 318 and no evap system. He went off and did something nuts and bought a $16,000 Chebby even though I was trying to talk him into getting a Babyfish or Dart. I know that being a Mopar forum, this isn't the ideal place to be asking dumb Chevy questions, but I figured there's plenty of gurus here, and fuel systems are pretty similar among most cars of that period. I'll have to check if his car even has a vent line to begin with. I was just wondering that if with no vent line or a plugged vent line, it would cause these conditions. I greatly appreciate the technical info, and I'll keep it in for my own vehicle!
 
JeremyAB95 said:
Car in question is actually my best friend's 69 Nova.
Click to expand...

I don't know a thing about Nova vent systems. You could have saved us a lot of time if you'd mentioned that "little detail."

For all I know, Chev might use vented caps (Mopar does NOT) and he might simply have the wrong fuel cap
 
67Dart273 said:
I don't know a thing about Nova vent systems. You could have saved us a lot of time if you'd mentioned that "little detail."

For all I know, Chev might use vented caps (Mopar does NOT) and he might simply have the wrong fuel cap
Click to expand...
Yeah, in retrospect I should've clarified it wasn't my duster in the first post - sorry. The main question was about fuel tank ventilation in general, and whether or not vacuum would stop fuel flow if strong enough. Many thanks to everyone who responded, the help is much appreciated.
 
First thing I would do is spend a few bucks on a new fuel filter...
But I would be inspecting the vent while I changed it.
 
You must log in or register to reply here.
-

Back
Top