Breaking up

[deiselpower]

I have a 1976 Scout 2with the 304 v8 with a holly 2 brrl, this thing is driving me nuts I have rebuilt the carb new fuel filter new coil new plugs new wires checked the timing and set it at10degrees advanced.my problem is it idels fine and throdles up fine in the drive way,but as soon as you pull the old girl out on the road and put her under a load like trying to go it starts breaking up bad..you get her up to 50mph and its acts like it is shutting off then it will come alive again slaming you back in the seat and continue doing this until it compleatly dies then it will start right back up and go again then start it all over again,any help please

 

[Michael Mayben]

Do a temporary installation of a fuel pressure gauge and watch it when the issue occurs.

Nominal fuel pressure for an IH sv application is 4psi>6psi at any engine rpm, witha delivery volume of one pint in 20 seconds. Very slight needle oscillation is normal/ok, wide swing is not.

An anomaly in fuel delivery to the carb can also be caused by poor venting (resulting in fuel starvation at elevated engine rpm/load) of the fuel tank...especially if the oem evaporative emissions system has not been maintained, or has had the typical po virus attack. To test this, simply remove the fuel filler cap and then go for a test drive.

 

[ronmc1954]

Agreeing with Mike, fuel flow, I had about the same problem with my 75 but mine was due to a pinched fuel line. I had removed the tank and when I re-installed it I pinched the fuel line coming off of the tank. The fuel pump would suck almost to the point of vacumn and when I shut it off or died fuel would slowly fill the line again.
Ron