Alright every one. I haven't posted much but I need a little help. Need some opinions.
I've got a 75 f250. 390 mildly built, 38s. So here's the back story.
Truck used to run absolutely fine. No carb problems what so ever. Ran great. Even got almost 12mpg. One day back in the mountains the carb randomly ran out of fuel. So I took a can and poured a little in the carb, didn't have a problem the rest of the day.
Fast forward a month or two. My Dad is visiting and were heading out to the mountains and it starts doing the same thing. Carb itself randomly running out of fuel. This time well driving on a paved back road. It Kind've acted like vapor lock or like the fuel was boiling. It would do it like every mile. So we turned around and headed home.
The day after he left, I go to start the truck and it acted like it was running on 4 cylinders. I popped the hood and there was fuel every where, all over the manifold, all over the carb. So I went a head and rebuilt the carb.

Ever since that its ran fine every where except when I start really bouncing around. It does the same thing, loses fuel. I went ahead and put an inline electric pump in so when it starts to crap out I flip that on to get fuel to the carb again and it fixes it for a little while.
Mind you I've checked for vapor like in the tank and lines, all good there. Has a good tank vent line. Also checked for hot fuel lines and I don't believe that to be the problem.
So as long as I don't bounce around everything is fine except if I go to town and hit traffic..it likes to loud up and sometimes loses fuel. But its basically been fine.
I know I need to tune it. I just ordered a book so I can get it all sorted out, or I may just put my predator back on. I know how to tune that haha.

But the other day I had it idling in the drive way and it did it just sitting there. Couldn't believe it.
So I really need some opinions on what could be causing the random loss of fuel. I don't think its the fuel pump. Although I've never replaced it. Maybe a heavy float or messed up needle and seat ?
Please give me any opinions you may have. Or if you need any more information please let me know.

Thank you all !!!


Edit: forgot to mention its a Holley 670 street avenger.

 

75...do you have an in cab tank? Either way, have you ever pulled the sending unit and looked at the pick up tube filter "sock". Replacing it might be the 1st step, as far as troubleshooting.

Start at the fuel source (tank) and then the pick up tube sock, then the consider then the hard and soft lines, insp any soft lines for dry rot. Then the mechanical pump and any inline filter, then the carb.

As far as boiling fuel have you ever put a old style cloth pin on a fuel line? Or looking to a phenolic carb spacer? https://www.google.com/?gws_rd=ssl#q...ic+carb+spacer

Fuel run over, sounds like stuck float.

Sorry I am NOT a carb experienced guy at all.

 

My tank does not have any type of in tank filter, and there's actually no way to put one in. And yes its in cab. I've blown out and cleaned the metal line coming off the tank. I've also replaced all the rubber line and I've checked the metal line on the frame for blockage. I run a metal filter right after the tank, which I'm going to replace again tomorrow and I'm going to run a second filter at the manifold as well.

I've actually been meaning to try one of those spacers. But honestly I don't really think its heat anymore.


One thing i haven't done is check the fuel pump for blockage but the thing that throws me is that its so random. Makes it harder to trace too. But maybe the fuel pump is old and the diaphram is breaking apart slowly sending debris into the carb. Second fuel filter should help that.


Its just so weird that I can drive around absolutely fine. But then it randomly won't get fuel and needs purged.

Maybe I'll even try a new fuel pump. Couldn't hurt. They're not that expensive.

 

A neighbor had a similar problem with one of his rigs. A random "running out of fuel" issue.
Found the culprit to he a shop rag someone had stuffed in the fuel tank. Every so often the rag would block the fuel pickup and the rig would shudder to a stop. Let the rig set a bit, the rag would drop away from the pickup and all was fine, until the next time.
It might pay to inspect the tank.

Good luck.

 

Thats a pretty good idea. I did look in there when I had the sending unit out a thousand times but didn't really look thoroughly. So I'll go ahead and do that tonight or tomorrow.

It did it again yesterday too. Drove to get the mail and did a lap around town. Everything was fine. Got back in the yard, just blipped it to spin the tires a little, then it decided to crap out.
Never did it this easy. I'm still wondering if its a carb issue.

But I'll get the tank checked out, get the new fuel filters, and maybe a new fuel pump and see what happens.

I've also got some different bowls I want to put on. Not sure if they'll fit, haven't looked yet, but might give them a try. See if different floats help it. Those bowls also have the fuel inlet a lot closer and would keep the line off the hot manifold.