Fuel Flow Issue?

Decided to drive the 1971 CJ5 10 miles to the nearest small town to run errands. Jeep fired right up, ran good to the gas station. Filled up some mower gas cans and Jeep tank, started out again with no problems. Hitting a small hill, I felt it start to cut out. After cresting the hill, ran fine. Next bigger hill, really started to cut out, seeming to be starved for fuel. Gave up and turned around to go back home. Ran fine until I pushed in the clutch to down shift for the final turn to the drive way and died. Parked it and could get it to restart, but it would not idle.

It seems to be a fuel starvation issue, but I thought I would see if there were any suggestions of where to start looking before I begin randomly replacing things. At this point I am guessing fuel filter, fuel pump, dirty carb, or a combination thereof.

This has the original 225 Odd Fire, but the original owner put on an Offenhauser manifold with a Carter AFB Competition carb. The other thing I noticed is that the return fuel line is blocked off, which I suppose would make it more susceptible to vapor lock.

 

You had me with fuel starvation until this:

If it’s fuel starvation or vapor lock, it’s more likely to idle and not run above that.
What’s the condition/age of the spark components?

 

Forgive me. How much gas is in the tank?

Also' "The other thing I noticed is that the return fuel line is blocked off, which I suppose would make it more susceptible to vapor lock." Blocked off? Unblock it and the motor should run again. Vacuum pressure in the tank will stop the flow.

 

Water in the gas. (?) Try some dry-gas and/or Seafoam before tearing into it.

 

If the carb has one of those stone style filters, take it out and see if it cures it. We had a SBC that was doing the same thing, turned out it was the filter that would starve it whenever we put a load on it. Ran fine at idle and lower RPM's.

 

The "stone" filters need to be cleaned once a year.

 

I had a similar problem. The filter *looked* clean. It wasn't...

 

It has a CRT Performance HEI distributor. I have never really messed with it at all since we've had the Jeep. Spark plugs are still in from when we bought it, so they probably could stand to be replaced.

 

Thanks to all for the suggestions. I will look for the stone filter and see if I can clean that. Also will add some gas dry. A couple easy things before I start replacing parts.

 

Note that you can run the engine from a can sitting on the cowl, with only siphon feeding the carburetor. If you connect up a siphon and it still won't run, then there's something blocking in the carburetor. You can also easily blow backwards through the fuel lines into the fuel tank. In a quiet environment, you can hear your breath bubbling in the fuel tank. Divide and conquer.

 

An AFB won't have the bronze "stone" filter. You should have an inline filter somewhere, be sure to check that.

 

I just had a similar problem,it turned out to be flakes of paint from a gas can that would plug the suction ,when stopped the flakes would float away and it would run.