Surging and cutting out
 

Hi, was hoping someone could give some advice on my 66 Fury

360 Magnum, Edelbrock 4 barrel, with an electric fuel pump.

Was running fine before...

I replaced the fuel tank and sending unit because of a leak in the tank.

Ran and drove fine for 20 min, then started cutting out, surging, backfiring through the carb. Would cut out when getting on the gas, but "sounded" fine with minimal throttle. Was unable to gain speed, eventually sputtering to a stop. After sitting a few seconds, I was able to start and drive fine for a few min, before it would cut out again. At that point I thought, maybe a venting issue or, fuel pump issue.

I replaced the fuel pump and checked the tank, It's definitely moving the fuel. So, out for another ride, 20 min in, it cuts out and does the same thing. It's not a 1 cylinder isn't firing type miss, more like a complete surge of them all.

I pulled over, pop the hood, fuel regulator holding steady at 5 psi. Hit the throttle at the carb a few times, broke up a little, fuel filter stayed full.

At that point, I started to think maybe it's something else. Pulled the air filter off, hit the throttle again and it shot a fireball at my face.

Now I'm thinking maybe it's the coil, but was hoping someone else might know what is happening or could provide some ideas.

Thanks.

Was running fine before all the listed items?

Yes, ran perfectly before the tank and new sending unit. The first long drive (after about 25-30 min) is when it first happened.

If I pull the hose before the fuel pump, fuel will flow out very fast by just gravity siphoning. I'm sure there are no restrictions. The regulator is reading a steady 5 psi as well.

WHat kind of ign do you have ?

Just a standard Accel coil.

Take it for a short drive with the gas cap off to check for good venting. Also, most recently I have witnessed a fuel pickup screen sucked up tight to the end of the pickup tube! Similar issues! Also a new tank and pickup install!

Thank you for the suggestions.

I did try without the cap and there was no improvement. I've really been trying to avoid pulling the tank back out, but it looks like I may have too.

Could simply be a tiny piece of debris made it to the carb needle and seat.or debris restricting filter during repair.

I'm kind of with the other guys..
I'm also thinking you have an issue with the newly installed parts, as long as it happed after that install. Something is blocked, restricted, would be my thought. I would double check and reflush the whole system from the carb back to the tank.

I swapped out out the new sending unit with the original. Haven't got to drive it around yet, but I see no issues with the new one. And now my gauge doesn't work again. :(

Yeah, it's still doing it :( It also has a very strong smell a fuel. I'm guessing because it's not being burnt.

It's so damn consistent too, always runs great for about 15-20 min.

OK.. So we can Rule out that issue.. Now you can swap back in the new one and know that that was not the issue, or that you had caused the issue when you swapped it...
Once you get that done, From what you just described, you could be fighting an ignition issue, that might have just came up at the same time for some reason?
Looking at the picture, Are you running an electric choke off the ignition coil? if so in hook it and see if that fixes the issue? you might need to also swap coils.

Yeah, at least I know that is not the issue now. My choke is electric and pulling power from the coil. I will try to unhook it and see if I notice a difference. I have a new fuel filter coming too but I doubt that is the issue. Hopefully tonight I can take it out and do some more testing. Thanks again for the suggestions.

Keep us posted....

Shadow -

What's your fuel pressure when it running fine and after 20 minutes?
If you don't have a fuel pressure gauge, get a cheap one and try it.

What else did you change or remove/reinstall ?
Fuel filter?

Archer

try running a jumper from the battery for the choke, I have had problems with the same setup. The fix was a different power lead for the choke.

Woohoo, fixed! It was the fuel filter. I had a small one I could take apart and clean. Apparently, I wasn't cleaning it right. I know I cleaned it after changing the tank but, it was clogged tight, could barely blow throw it.

Thanks again everyone for the suggestions and help!

Shadow -

Why did I think that was it???
It's not like that ever happened to me ... :hide:

Archer