I'm working on a '69 f250. The engine is a 360, post-rebuild approx 10000 miles, but it's been sitting now for about 4 years.
I just replaced the clutch, changed the oil, and put in all fresh tune-up parts, plugs, wires, cap, rotor, points, condenser.

It acts like it is starved for gas. I pulled the line from the fuel pump to the carb, blew it out and replaced it. It was set up through a fuel-tank switch between the main tank and two tanks in the bed. I bypassed the switch and routed the main tank straight to the pipe, and while I did that I noticed that gas didn't exactly gush from the tank. I haven't done much with fuel systems, but it seems to me that it ought to run out of that little pipe at a pretty good clip.

Should I prime the pump, and would that do any good, and if so, how do I do that?

Thanks

 

I would consider changing the gas. It's most likely varnish by now. I would also check the line right before the carb to see how much actually pumps out while cranking.

 

make sure to check your fuel filter too.

 

The gas is mostly fresh, I put 5 gals in yesterday and siphoned 6 out last night. But I really think the tank must be clogged as nothing comes out of the outlet pipe when it's completely disconnected. It appears that today I get to remove the tank.
Whee
Thanks

 

Blow out the lines under the truck, and check the rubber connecting hoses. "Common spot". The rubber can swell and crimp the flow. Also rust rocks can build up and clog it. Does the pump itself have a filter canistor? IF so, make sure it's not clogged. Offhand, I'd say you have a tank to engine path clog. Thats the usual place. MK

 

I'll do those things, but like I said, when I disconnect the hose from the outlet under the tank, nothing comes out of the tank itself.
Thanks

 

I'd try taking off the fuel pump. On my 302 it's just held on with two bolts right next to the oil filter. Really easy to get at. After you get it off, pump the lever up and down some while someone holds their finger on the line in. You should get some good suction coming from there.

If you don't have any, my guess is that debris got in and fouled up the fuel pump. Check out the canister filter on the bottom. If this is what happened you'll see junk in there - probably rusty bits from the gas tank.

I didn't need to prime the pump any when starting up for the first time in over 2 years. Of couse I ran the engine for awhile and junk got sucked into the fuel pump, messing it up. I'm dealing with the garbage in the gas tank right now. Will clean it out soon and the two in-line filters I installed between the tank and fuel pump shouldn't clog up anywhere near as often. I really like those clear fuel filters so you can see what's going on inside.

 

I'll do those things, but like I said, when I disconnect the hose from the outlet under the tank, nothing comes out of the tank itself.

Hummm. Sounds like either the line out of the tank is clogged, or the tank itself is clogged at the pickup, or hole. Bet your tank has some rust in it.. Had that on mine. Like the other poster, I keep an extra inline filter from the tank to the pump. Then I have the one in the pump itself. Then I have one more from the pump to the carb. I think it's fairly normal for gas not to rush out on those tank and lines, when you unhook a hose. For one thing, you would probably need to take the gas cap off to make it flow faster. Speaking of which...Make sure your tank is not collapsing due to a funky gas cap. Probably not, but worth a mention...MK

 

I've pulled the tank, blew out all the lines from the tank to the pump, and from the pump to the carb, they're all clear. I now realize that the gas outlet from the tank is at the top and the tank operates on a siphon type principle. I guess that's a safety measure. However even when I try to back-flush the tank itself with compressed air (regulated down to about 25 psi), nothing happens. I'm about ready to try drano! (not really, I may be stupid, but I'm not bloody stupid!--Richard Harris-'Juggernaut'). None of the junkyards in the area have a tank, so I'm to the point of trying to clear this one. I've run a piece of stiff wire down the pipe to no avail. What does anyone reccomend in the way of chemicals?

 

This great gimmic came to mind. Fence wire by itself was too stiff to get through the pickup pipe inside the tank, so I bent the end back about 1/4 inch to make a hook, put a pipe cleaner in the hook with about an inch above, and crimped it tight with vice grips. This left about 5 inches of pipe cleaner going down the pipe ahead of the fence wire, and it would twist like a miniature snake. I knocked the clog loose, flushed it with about a pint of acetone, then it would blow out. I did something stupid, though, with the tranny, back when I was doing the clutch. I drained it, and removed the top with the shifter assembly to make it easier to move on the jack. As I was putting it back together, a bolt fell into the tranny, so I turned it upside down. The bolt fell out, but next to it on the floor, there was also an 'o' ring, about 5 inches dia. There was no oil residue on it, no wear marks etc. I got the forks positioned correctly, made sure when I cranked the engine with the starter that I could hit all four gears and reverse. It's a New Process, the only marks on it are NP in the center of a circle with radiating spokes, and the number '69'. Any New Process transmission experts out there to tell me if this o ring is actually part of the tranny, or not? It's possibly part of the seal around the boot. I did not loosen any bolts around the seals at the input shaft, or output shaft. I did not remove any gears or other transmission assemblies like syncro, etc. Until I get the tank back in and cleared, I'm not going anywhere with the rig anyway.
Thanks. Perhaps I am bloody stupid, but at least I didn't use drano in the gas tank.

 

I have the same problem, no gas comes out of the rubber hose right before my (2nd NEW) fuel pump. I'm assuming there's rust in the gas tank or line. Can someone explain (in detail) how to remove AND/OR clean the lines up to the fuel pump?
Is it something that a "wanna-be mechanic" can do?

 

I ran into the same problems with my old 71....but it had been sitting for about 15 years....took the tank off and cleaned it out, but still getting a little rust from time to time....had to replace the filters a couple of times.....I don't get to drive it that often...but this past weekend, it ran like a top....guess they get better with age....Am hesitant to upgrade the motor much now....it might jump out from under me......lol

 

When I was checking for rust in the gas lines I just disconnected the rubber hoses from each section of line and blew through it from underneath the truck. There wasn't any gas in there to worry about and it didn't take too long to find out that the problem wasn't with the fuel lines.

I noticed that on my truck the front section of metal fuel line must've been installed early on in the factory because there's no way I could snake that thing outa there. The piece coming out of the gas tank and the first one under the truck that runs back inside the frame can be taken off so you can clean them out without lying underneath the truck. Honestly, I'd be tempted to replace a clogged section rather than unclog it if it looks bad on the outside or it seems to be damaged on the inside.

 

Is it expensive to replace the gas lines on a 71 f100?

 

My suggestion still stands, use electric fence wire, or .035 or .025 welding wire, bend about 1/4 in back, and lay a pipe cleaner in extending the length about 4 in., crimp it tight with vice-grips. It makes a great snake. I suppose you could twist more pipe cleaners to make it longer. Wouldn't try it on the long runs from the tank to the pump, though. That'd be a pain in the ***.