[extracarter]

i have a 70 charger r/t. she runs strong but i am having difficulties troubleshooting why it acts as if it wants to give out of gas after i drive it for 20 minutes. i have a 440 hp .30 over with a 750 cfm edelbrock carb. any suggestions that would help me would be greatly appreciated.

 

[stepside454]

Ive had simialer happen with fuel pumps failing, make sure you have good fuel pressure

 

[extracarter]

i dont have the tools to measure fuel pressure, but it appears to pump out strong and it is a mechanical fuel pump not the electric type. i try to keep it simple. thanx for the reply. looks like to the shop we go....carter

 

[boatbob2]

carb.........

hi,i ran into a problem kind of like that a few years ago,we pulled our hair out over it. what it would do,was run fine at a slow speed,but at 60 mph,it was like turning the key off,at 45 it would start again,.at 60,cut off again. we checked everything out,finally we took a long gas line hose,ran it into the gas tank,duct taped the hose to the side of the car,then put the end of the hose into an adapter,and then into the fuel pump,we could run 100 mph like that with no problem,we hit the books and found that there was NO envelope type filter inside the tank,we dropped the tank and there WAS a filter inside the tank,it was plugged up. we changed the filter and added another filter to the chassis and had no further problems..im Boatbob2

 

[extracarter]

thanx, boatbob. all replies are greatly appreciated. i will also check my tank.

 

[donwesen]

Carb Problem

Had a similar problem which turned out to be too much heat on my gas line. There was a spot where is was about 6 inches from my exhaust and when it got hot the gas in the line would vapourize and the car would not run right. Moved the line and problem was solved.

 

[red65mustang]

my first choice is with stepside....
when the motor is cold, and the worn pump and "stiffer" diaphram are still cold, the pump makes enough pressure.....when motor heat heats up the pump the worn diaphram goes limp and makes less pressure....Edelbrock needs about 3psi minumum (maximum 5.5psi)
pretty easy to test, find a friend who will loan you a 10psi guage, use a "T" fitting and some hose to connect it at the carb and check the pressure cold and hot...
leave the guage connected showing psi with the motor turned off, the line should hold pressure for up to 5 minutes proving there are no leaks, the floats are good and the check valve in the pump is working....
if it looses pressure pretty quick and you are sure the line doesn't leak, it's a good indicator that crap has gotten into the pump....so change the carb filter as well....it maybe clogged

also agree with boatbob....."fair to good" chance rust scale from the "gone tank pick up filter" is the source of the ruined pump problem
my solution, a must, for any old car/tank is a clear plastic (Purolator $5) or glass filter on the line into pump to catch the crap coming out of the tank before the it gets to the pump

a simple test and possible partial remedy for a clogged pick up is remove the gas cap, disconnect the tank line at the pump and blow compressed air up the line to blow off some of the scale on the pick up....the clear filter at the pump from the tank should have some gas in it to prove the tank line is clear....(do it as routine maintenance cause a mopar tank and pickup ain't cheap?)

 

[harvey kempema]

I had the same problem with 2 cars over the years---catalytic converter was plugged---but yours is a 1970--some enviromentalist didn't put one on your car...did they ????

 

[slvrbllt]

Pull your gas cap when it happens and see if
you have a vacume on the tank, if you do,
try a vented gas cap.