ok on my 79 150 4x4 351 with a 4 speed it keeps cuting out at highway speeds runs like a bat outta hell through 3rd but when i get into 4th going down the highway it sputters and jerks like its running out of fuel (so if u slow down and let it idle with cluch in idles perfect and will take off and run again)so i rebuilt the carb checked all the vacum lines and it still doing it ???????? any ideas here guys im stumped.. ps. it has good fuel line pressure

 

sounds like you need to just drive around in 3rd gear all the time.

or

I'll trade you. you gimme the 4 speed and I'll give you my 3 speed.LOL

 

Check the float level in the carb, and if it's good then it's probably a sign that the fuel pump is on its way out.

 

LOL yeah but the 4:11 im running i could only get it up to about 50 in 3rd

 

ok well i did calibrate the float when i rebuilt it today,,, so ur thinkin fuel pump i have a extra one ill put on and see if that clears it up

 

ok changed fuel pump still doing it anything you guys can think of it might be

 

Did you check the fuel filter?

zenmaster

 

Sounds like you need to check the volume of fuel reaching the carb and if the pumps good must be a restriction in a line somewhere. if you take it easy up thru the gears will it run in 4th for a short time? I just pull the fuel line and run the end into a measurable container, you should have about one ounce of fuel for each pump if I remember closely, someone will correct me if I am wrong I hope. so a dozen pumps would fill a 12 oz bottle or so, could be a weathered fuel line also sucking air too..

 

yeah because im running 4:11's i can shift in 4th at around 20 mph then going easy on it it will go for a while but then start cutting out like half the cylinders are'nt getting fuel( but i can climb on it throgh 2nd and 3rd runs like a champ) ...... but even when i first hit the gas it dies out for a second then picks back up again like when you shift so tommorow i will try your bottle idea and see if thats the problem thanks.. for the info