Air in fuel line

-
Al Dusty73

Al Dusty73

Member
Joined
Oct 4, 2020
Messages
19
Reaction score
0
Location
California
Hi i have a 1973 Duster 225 and my fuel filter is not getting gas, just bubbles. I replaced the pump, lines, rebuilt the carb'and looked all over for any type of leaks. Do any of you have any suggestions on getting my car running?
 
Al Dusty73 said:
Hi i have a 1973 Duster 225 and my fuel filter is not getting gas, just bubbles. I replaced the pump, lines, rebuilt the carb'and looked all over for any type of leaks. Do any of you have any suggestions on getting my car running?
Click to expand...

Rather than looking in the filter, check the accelerator pump shot in the carburetor throat. Look into the carburetor throat and operate the throttle. If you have a good stream shot of fuel when you activate the throttle, you have other issues. Most of the time you will see lots of air in the filter but gas is going through. If you do not have a good pump shot, your next step would be to remove the fuel line from the carburetor, attach a long hose to the supply line and put it in a bucket and spin the engine. If it's not getting gas there, disconnect the outlet at the fuel pump and put a pan under it and spin the engine again. If there is no gas at the pump and the pump is as you say new, your next step will be to remove the tank and inspect the sock filter on the end of the inlet to the sending unit to see if it's stopped up with fifty years a crap. Also inspect the gas tank as well and clean or replace as necessary.
 
RustyRatRod said:
Rather than looking in the filter, check the accelerator pump shot in the carburetor throat. Look into the carburetor throat and operate the throttle. If you have a good stream shot of fuel when you activate the throttle, you have other issues. Most of the time you will see lots of air in the filter but gas is going through. If you do not have a good pump shot, your next step would be to remove the fuel line from the carburetor, attach a long hose to the supply line and put it in a bucket and spin the engine. If it's not getting gas there, disconnect the outlet at the fuel pump and put a pan under it and spin the engine again. If there is no gas at the pump and the pump is as you say new, your next step will be to remove the tank and inspect the sock filter on the end of the inlet to the sending unit to see if it's stopped up with fifty years a crap. Also inspect the gas tank as well and clean or replace as necessary.
Click to expand...
The carb is great. I bought a electronic guel pump a few minutes ago and i will be installing that tomorrow. My dad says its probably clogged so we will check that tomorrow as well. Everything from the fuel pump back has been replaced. Thank you!
 
If everything is "new and good" then why are you having to put an electric pump on it? My 56 year old Valiant runs like a swiss watch with everything on it just like it came with. If you're having to put an electric pump on for it to run something is WRONG. Remember, new doesn't mean GOOD!
 
RustyRatRod said:
If everything is "new and good" then why are you having to put an electric pump on it? My 56 year old Valiant runs like a swiss watch with everything on it just like it came with. If you're having to put an electric pump on for it to run something is WRONG. Remember, new doesn't mean GOOD!
Click to expand...
I started replacing stuff after my car died in traffic. This is my first car and I am doing as my dad says. Sorry for the misunderstanding.
 
Electrics are fine. Many benefits, minor drawbacks. If your car sits for a while, electrics are the cats ***. An underdash switch makes for a decent theft prevention too. Usually there are air bubble evident in the clear type fuel filters, especially if they are horizontal. Make sure your choke is 100% operational, ie pulling off completely when warm and snapping "on" when cold with first pedal set.
 
pishta said:
Electrics are fine. Many benefits, minor drawbacks. If your car sits for a while, electrics are the cats ***. An underdash switch makes for a decent theft prevention too. Usually there are air bubble evident in the clear type fuel filters, especially if they are horizontal. Make sure your choke is 100% operational, ie pulling off completely when warm and snapping "on" when cold with first pedal set.
Click to expand...

No doubt. My point was, if his car will not run without one, somethin's up. Tally ho and have fun!
 
Take the filler cap off and try again. If the tank venting is wrong you will not be able to pull fuel from the tank.

Also please post photos
 
  1. Is there fuel in the tank?
  2. How much fuel is in the tank?
  3. Are the parts from the fuel pump back OEM style parts?
  4. Are they year correct?
  5. Did Anyone modify the tank venting from stock?
  6. Have you run a hose from the inlet of the mechanical fuel pump to a can of fuel and cranked the engine over to see if it will start?
  7. How long did you crank the engine after replacing all parts from the fuel pump back?
  8. Al Dusty73 said:
    also i am not getting any gas in the filter so it isnt cranking
    Click to expand...
    the engine will crank assuming the battery is charged. "Will it crank" is not dependent on the engine getting fuel.


  9. You can pore some fuel into the carb and the engine should run for a few seconds.
I know that it is a lot to go over BUT for anyone to help we need a ton of info
 
Take a peek at the rubber jumper from the sender to the line, back at the tank. The jumper is above the liquid line. If the line is cracked or the clamps loose, the pump will suck air there instead of bringing up the fuel. Actually, the pump doesn't suck at all, it just reduces the pressure in the tiny cavity within the pump. Atmospheric pressure enters your tank thru the vent, and PUSHES the fuel, towards that low-pressure area. If air enters the line somewhere else between the pump and the fuel, then the atmosphere just takes the shortcut.
BTW;
You will find a metal strap across that jumper; this is a ground for your fuel gauge. If you leave it off, your gauge won't work.

Won't crank, and won't start, or even won't fire, are all different things. And the cures for each of them are all different.
 
Last edited:
I have a friend with the same problem (79 Volare). It will eventually get fuel to the filter/carb, after much cranking. A lot of air bubbles in the filter. After some trouble shooting including substituting a electric pump under the car, I'm pretty sure it is either the rubber hose at the tank, or a problem with the pickup and/or tube inside the tank. Either way requires lowering the tank on this car.
 
A quick method:
We used to blow shop air into the line feeding the fuel pump back into the tank. In theory it dislodged any crap and would blow the strainer sock off.
Not a preferred method, but works quickly in a pinch, especially if you are changing out the engine soon.
 
Joey4speed said:
A quick method:
We used to blow shop air into the line feeding the fuel pump back into the tank. In theory it dislodged any crap and would blow the strainer sock off.
Not a preferred method, but works quickly in a pinch, especially if you are changing out the engine soon.
Click to expand...
Don't want to do that, as I suspect a air leak, not a clogged sock.
PS: If you do blow air into the fuel line, make sure the filler cap is removed. Doesn't take a lot of pressure to deform the tank
 
AJ/FormS said:
Take a peek at the rubber jumper from the sender to the line, back at the tank. The jumper is above the liquid line. If the line is cracked or the clamps loose, the pump will suck air there instead of bringing up the fuel. Actually, the pump doesn't suck at all, it just reduces the pressure in the tiny cavity within the pump. Atmospheric pressure enters your tank thru the vent, and PUSHES the fuel, towards that low-pressure area. If air enters the line somewhere else between the pump and the fuel, then the atmosphere just takes the shortcut.
BTW;
You will find a metal strap across that jumper; this is a ground for your fuel gauge. If you leave it off, your gauge won't work.

Won't crank, and won't start, or even won't fire, are all different things. And the cures for each of them are all different.
Click to expand...

This ^^^^ is another excellent thought.
 
Dana67Dart said:
  • Is there fuel in the tank?
  • How much fuel is in the tank?
Click to expand...
Seems obvious but with an after market sender ( my assumption based on "we replaced everything from the FP back")

With only a few gallons in the tank it might be sucking air (yes I know it doesn't actually suck)

Also with a totally dry "new" system it might take more time than expected to get fuel to the filter / carb
 
Sorry this is a lot to respond to. I replaced the little rubber hose the comes out of the tank. I cant check for modifications. I meant from the fuel pump to carb. I filled it with gas. The fuel pump was to get gas into the filter. The next step is looking in the tank. Thank you all for your help and i will post updates on what I find!
 
Not sure I understand your post.
Please elaborate on what you have done.

The more info the better.
 
I replaced the harfline and it runs like new. Sorry for the late update. Thank you guys for the help.
 
The little hose at the tank..from the sender to the hard fuel line. It cracks and you get aireated fuel and even a leak.
Other check is the fuel pump diaphragm, it can crack and leak into the engine...oil..smell it at the dipstick...and little to no fuel psi.
 
Al Dusty73 said:
replaced the harfline
Click to expand...
You may need to edit your posts after you click post reply.

Not being a dick just have no idea what a hardline is!

Also it would be nice if you described in some detail what in total you did.
 
You must log in or register to reply here.
-

Back
Top