Was wondering if someone may help me out with what may be going on.

After driving 45mins on highway my 1979 starts to chug and sounds like it is starving for gas. If I slow down or pull over and let idle for a few minutes, I can go and everything is fine for a few more miles and then happens again.

I notice this only on driving for longer periods.

Any guesses?

 

What troubleshooting have you done?

Change the fuel filter(s).

 

It is a new crate engine and replaced the fuel filters when I swapped the engine.

I guess I could replace the fuel filter.

I had a cracked block before and I guess it is possible that I had tons of junk in the fuel lines and collected in the new filter.

I haven't done anything though. I wasn't sure where to start.

Jeff

 

Starving for gas: when you give it throttle. it will quit or it will fall flat then backfire through the carb and have a short burst of energy and fall flat again.

 

Check fuel filter for clog, check tank vent for clog (as a diagnostic you can run with the cap loose), check for old fuel lines. Old rubber lines can get sucked closed by the fuel pump.

 

Replace the fuel tank I had this same stuff happening on my dads truck seemed to idle nicely ran great for awhile full of fuel long story short replaced the tank and it runs like a stinking champ again check the bottom sump area it was rotted out and leaking on his.

 

Open your gas cap and see if it sucks a bunch of air in when this happens. Replace cap. Check vent line.

 

The "filter" (sock) on the fuel sender pickup tube could be clogging up.