OK, 69 Roadster 350/350 L46 Original. Owned for about 1.5 years now.

Idles great and revs great but when you accelerate it seems to be starving for gas. Acts like you are running out. I've eliminated ignition items for now (replaced everything.) Had a couple guys take a ride that know cars and said it is starving for gas.

I put an extra carb on and same issue so I know it is not that. Examined the fuel delivery system and it would appear that I have a new tank, new sending unit and all the lines look to be intact and healthy. So I put a new fuel pump on and the issue did not go away. Made sure the pickup screen in the tank was not plugged. I also blew air from the engine bay back to the tank through both lines. My next step will be to replace the inline metal fuel filter that is between the carb and fuel pump. How do these filters work with the return line? Is there an internal flap for the return? I blew the return inlet with air when I was replacing the fuel pump and noticed I couldn't get air to go out the pump side of the filter. Then later I thought I could before I put it all back together. Can somebody tell me how this type of filter works and how to diagnose a problem with it? I'm hoping this is the issue. If the filter is blocking the return line then that would cause the "running out of gas" system correct?

Thanks guys!

 

check the rubber hoses.. sounds like they are pinching off...

 

Sounds like a tuning issue. Just replacing the carb obviously didnt solve it, but make sure to check your fuel bowl levels. Low bowl levels can definatley cause the car to stumble on hard acceleration.

Joe

 

I doubt the return line has anything to do with it. I've got mine totally blocked off and everything seems to work OK. Make sure you have the correct "S" rubber line between the metal fuel line and the pump.

 

I double checked the rubber lines and they are new and not pinched.
Two known good carbs and I have the same "no gas" issue. There is no back firing and no stumbling, just cuts out like it runs out of gas.

 

If it is surging ,check PVC valve/and or a possible air leak into manifold vaccum...

 

It is not surging. PVC valve is a OK and I replaced the intake manifold gaskets and blocked of the vacuum lines at the manifold while troubleshooting. Man, this is getting tough to figure out.

 

THIS IS CRITICAL!!! I had a bad fuel line last year and just went with an off the shelf piece of fuel hose... it started doing the exact same thing that yours is doing. I bought both lines thru Mid-AM for almost nothing!

 

If you are running a stock ignition, make sure your point gap isn't too close!!!! Check for proper DWELL rather than just setting with a feeler gauge.

 

QUIZ.
what test would i do?
(hint, duct tape needed)

 

Can I drive with my eyes covered??

 

OK, I solved the problem. It is the in line fuel filter. Not sure what was wrong with it as it only had about 300 miles on it. I cut it in half to see what the problem was and could not identify anything. I verified the issue was the filter by using a piece of flexible fuel line in its place and plugging off the return line. Ran great but seemed slightly sluggish (kind of a rich condition.) What is the return line for? I assume it keeps high pressure from building up and the car ran rich because of it?