Problems...unsure of where to go next

Yup that's the one. I guess it's not the "super". So I'll grab a lower resistance coil and see what happens. I don't have the original it was shorted to ground and I threw it away.

 

I know you said you changed the rubber fuel lines .. but did you change them all ? Most of the time I've seen them they get brittle and crack a bit causing a leak but sometimes they get squishy and can suck together ..

.. As Jason said, the only real way to monitor fuel flow is with a temporary gauge setup and about the only way to plumb it is either to hack up a good fuel line inserting the sender or to just fab one up saving your original for later use. Best to find someone with a good bender and flaring tool who knows how to use them both .. or drive over to Jason's house with some beer and the latest issue of Ammo magazine

 

You know J. .. I bet that if you bent up a few sets of lines - spec'd to fit a good sender and placing it in a good spot - you could prolly sell them easily here.

.. I'll accept 7% beer royalty accordingly

 

I thought this looked familiar .......

https://www.summitracing.com/parts/acc-2010acc/media/instructions

https://www.summitracing.com/parts/msd-61001m

Larry

 

Yup same thing.

I tried new MSD low ohm 0.7 coil. Same problem persists.

 

With the engine off, does your air valve stay open if you manually open it all the way or does it close on it's own? I've seen this happen and the car would act as you described.

 

Had the same symptoms after I got an old car running after sitting for a long time, the rust in the tank flaked free, piled up on the bottom of the tank and surrounded the pickup! Simply from driving on the crappy rough Michigan roads shook the rust off the inside of the tank which then caused all my problems! ou:

Would fill the float bowl while idling, but couldn't keep up with demand while just cruising! I still had the 2bbl on at the time this happened so it didn't have that big of a float bowl to fill either!


Never even suspected the tank because of how nice it looked on the outside for being SO old, but the outside surely didn't represent what the inside ended up as. The fix was a new tank, I didn't want to try and get all that rust flake out to try one of the coat the inside of the tank fix kits even though they're less than a new tank they're a lot more hassle. Something to look for anyway. GL




Derek

 

Well, It seems as though I was in the same boat. I have a new sending unit to install and planned to "clean" out the tank once dropped. I've been holding off to do it at my buddies shop where I have a few extra hands and a lift.

I blew out the lines a few times before but just did it again in a pulsating pattern for several minutes and I could hear a change in the venting sound of the tank by the end of it. I also hit the floor pan in the trunk repeatedly with a rubber mallet. And wouldn't you know it, issue gone!! YAY!!

I went ahead and put another new filter in the carb and added an inline unit to help keep the carb happy. Now to drop the dam tank.

Thank you everyone who helped with their input. I'm the the brightest tool in the shed but I like to get my hands dirty and learn. Atleast I know everything else is top notch.

 

Don't overlook this suggestion. I had the same exact symptoms as OP describes with my 70 Chevelle SS. After doing a hard pull, it would begin to stumble, especially if the tank was less than half-full.

I eventually diagnosed the problem when I ran it hard immediately before pulling into a gas station to fill her up. I could barely get the gas cap off there was so much negative pressure in the tank.