Fuel problem?

After working most of the day in the garage I felt like taking the Jeep out to give myself a break. I didn’t get far before my 258 backfired out the exhaust while coasting down hill. On my way home it backfired again then stalled. I checked things out and all wires seemed tight all appeared normal. The only way it would start was when I had the accelerator to the floor, this same thing happen two more times on the way home. The engine runs great when idling or on acceleration.

The fuel pump has never been replaced so I thought it may not be putting out the volume of fuel need. I ran down flaps grabbed a pump for $17 and installed it, also the metal fuel line coming from the pump to the carb was toast so I picked up some 5/8” brake line and rerouted it in front of the valve cover instead of over it. ( just looks better to me)

So, I’m off on my second run and it ran great for about a half hour then while coasting it stalled and started the same way as above, but after changing the fuel pump it never backfired. When I got home and turned off the engine I notice that there were air bubbles in the glass filter flowing in direction from carb to the pump this went on for about 10 minutes to a gradual stop. I could also hear what sounded like the carb bowl filling up with fuel, not sure if either is normal never noticed it before.

There were no leaks anywhere it has a 2 year old Holley carb. Float issue? Or other? Thanks in advance for your help.

 

Back fire to me would be timing, ignition cutting out(bad ignition switch?), de/accelerating down hill back fire exsaust manifold leak letting in cold air, maybe the Condencer going bad, coil over heating and breaking down(runs Ok for a while after cooling off) but vapor lock just cuts off the fuel supply and engine stops till you cool the fuel off again. Weak fuel pump would not let you do high speeds it would surge as the bowl fills up, low float level would cause you to run out of fuel on hills or hard acceleration, accelerating again uses up the fuel, craps out again till you let off long enought to fill the bowl some more. Check your ignition just to make sure every thing it working right. Check the color of the spark when it is running bad if yellow change the condencer. if weak check point gap. Just a few things to look for. Mark

 

Boiling fuel is due to lines to close to hot parts of the engine, lean running engine making the motor run hotter(lack of fuel will cause this like low float level) try re/routing the fuel lines, heat sheild ect during hot weather to stop fuel boil or vapor lock. Mark

 

Mark thanks for the reply, very helpful. I failed to mention that I did notice a manifold exhaust leak, but it stopped backfiring after I installed the pump so I didn’t mention it. The new pump may not have made the difference rather the hot weather played a bigger part of it not backfiring.

The 79 258 has the electronic ignition, but I will check the coil, ignition switch and timing.

All my engine compartment metal fuel line is covered with 5/8” hose with stainless steel over that. The only exposed part is the glass filter.

 

Search a little more into the electrical and found a loose connection on the baluster. Once that was tight the engine ran great. Thanks for the help Mark.

 

Them darn Eddy Electrons need to flow to keep them running. Glad you found the problem. Nice when it is a bad conection cheaper fix! Mark