I bought my 79 last year. It has a 460 with an Offy manifold and a Holley carb. The carb may be oem for Ford. It is stamped 80457-8.

Continuously, when running on the front tank, it will bog and stutter.

Occasionally, when running on the rear tank, it will bog and stutter. Last week, it ran pretty good. This week, it ran pretty bad. On acceleration, it would bog and hesitate. At cruise, it would sometimes bog and then pick right back up.

I keep the fuel tanks at least half full, although the PO told me he ran off the rear only. I suspect the front tank is all crapped up, as it generallly runs fine off the back tank.

I'm considering the fuel pump, but it seems fine at idle and during volume testing into a bucket. The pressure gauges I see work inline which makes them very difficult to see when driving.

Replacing a tank (one at a time) is an option that will have to wait until school is out. May or June.

Any advice is appreciated.
--------------------------------
PapaBearYuma
79 F350 460 C6 4x2
78 F150 351m C6 4x4

 

If the volume test on the pump looked good (nice work), then I'd put the fuel pump at the back of the line for now. How long since the fuel filter was changed? If you don't know, or you haven't done it yourself since buying the truck, I'd replace that first. If you have more than one filter, replace the others too.

It would also be pretty straightforward to drop both tanks and have a radiator shop clean them out.

 

Have you tried taking some fuel system cleaner to it? Worked with my 91 Ranger STX once upon a time when it was having the same issues as you're describing.

 

I put a new, see-thru, fuel filter between the pump and the carb 2-3 months ago. I haven't done a thorough search, but I didn't see any other filters.

New replacement tanks are just over $100/each. Any idea what a radiator shop would charge to clean one up?

Have not yet tried fuel system cleaner. Any recommendations? The counter kid at AutoZone keeps trying to sell me fuel injector treatment. I don't bother trying to explain...

 

I dumped some Seafoam in my tank soon after I bought my truck. It was running like crap from sitting for a few years and seemed to help.

 

The other thing to check is the rubber fuel lines. With time and alcohol they break down and get very soft. The fuel pump can suck them closed causing power loss or stalling. On my truck ('78) the flex lines used to install the second tank were poorer quality and failed first. A few feet of 3/8" fuel line and a few hours will take care of them all front to back.

If your carb has the small filter that screws into the carb it plugs easily if there is crud in the tanks. Sugest repacing the filter at the carb along with the filter you added. The added filter is a good idea and will protect the little filter at the carb.

 

I tend to use STP fuel treatment and injector cleaner in my stuff. And yes, the injector cleaner does help with carb'd stuff, too. Iso-Heet with cleaner is good stuff, too.

 

I don't recommend fuel system cleaner at all, especially on a carbureted vehicle with a sensitive needle and seat. At best, it will only pick up varnish and crud, and move it to somewhere else that it shouldn't be.

I don't recall the cost of cleaning a tank but I remember being told that it is much less than the cost of a new tank. Nothing a quick phone call won't answer.

 

I was moving the yellow truck around to the back of the house, and it stalled out on me - acting just like it was out of gas.

Checking for Air, Gas, and Spark, I thought I saw a bit of spray from the accelerator pump, and could see that I had spark. Air seemed good, too.

I got it to fire up again, and then it backfired. The backfire lit the crankcase filter inside the air cleaner on fire. By the time I got the fire out, and pulled the air cleaner off the carb, I had a nice orange puddle where the filter had been!

With Winston cheering me on, I pushed the truck back down the street and aligned it with the driveway. I then used the brown truck to drag the yellow truck back into the driveway.

I pulled the hose to the fuel pump and dropped it into a gas can. Truck started right up and ran fine.

Pulled the front tank and found a surprise:



Without the extra length provided by the filter, the tank was basically empty at the half-way point. New filters from Bronco Graveyard are on the way!

 

I was going to suggest the in tank filter but you beat me to it.

 

Yellow truck - 79 F350 460 C6 Dual Tanks

Truck runs perfectly fine from rear tank.

Truck runs out of gas when running on front tank.

Pulled the front tank and found the pickup filter in many pieces on the bottom of the tank. This allowed fuel to only be pulled from the top half of the tank:



Ordered up replacement filters from Jeff's Bronco Graveyard. The hose connecting the tank to the hard line is bent 180 degrees. I changed it out, and filled the tank, yet the truck failed to run on the front tank. I figured the new hose was kinking, so I put the old one back on.

No joy. Figuring the lines were crapped up, I pulled the hose from the tank, and routed it into a can. I pulled the hose from the fuel pump, and stuck the nozzle from the air compressor on it. Blew it out, and some crap went into the can. Truck still failed to run from the front tank.

Checked the hose connecting the hard line to the dual tank switch. It looked a bit rough, so I changed that one out. It, too, has a hard bend that may be kinking. I put a clamp on it in an attempt to hold it round.



Figuring the fuel pump may not like pulling the fuel up all those lines, I used my a/c vacuum pump to pull the air out of the lines, and bring the fuel to the fuel pump. Ghetto, I know, but it worked:



The truck ran on the driveway for a half-hour before I shut it off! whoopee!

Then I drove it into town. The twenty minute drive went fine. Then I parked it, and when I returned from shopping it started right up. It ran to the intersection, then it died - out of gas. Switched back to the rear tank - fired right up.

What gives!?!?!?

I guess the fuel pump could be collapsing the soft hoses making these hard bends?

I've spent many hours looking for "formed" hoses, but no luck.

So I humbly turn to the experts for advice....

 

I would be tempted to pull the selector valve out and make sure some of that *rap from the pickup screen didn't lodge in it or that it isn't working correctly.

Do you have the part number for those filters? Thanks!
.

 

Sending Unit Filter,

 

Thanks! I'm going to be pulling three systems apart and Ford wants a small fortune for one.
.

 

Tonight I pulled out the fuel switcher and cleaned it up. It seems to work just fine. When flipping the switch to change tanks, you can hear the clank from the solenoid all the way into the cab!

Alas, that failed to fix the problem. So I ran a length of hose from the fuel tank pickup to the switch, bypassing a hard line and two hose connectors. So far, seems to be working.

I'll have to secure the hose better before I dare drive it around, but it's a start...