This was brand new Gates hose. I replaced all of the hoses between the pump and tank last year because one of them was leaking and the rest were all dry and cracked. I tossed the spring clamps and used new worm gear hose clamps on all the connections. I've checked for kinks and the clamps are all tight. Its definitely vapor locking because it would only run as long as there was gas in the carb last night until I poured cold water over the pump and the line going up to the carb. Immediately after that it stayed running on its own until I finally shut it off. Whenever it stalls the carb is always dry and it refuses to pump fuel until it cools off or as I found out, pouring cold water on it also works. I have no idea why this started after replacing the hoses...if it was just stupid coincidence to add to my frustration or what...but I've checked the routing and condition of the hoses several times but couldn't find any reason for it. I only insulated the hose leading to the pump from the tank last year but it appears to be vapor locking in the pressure line which makes me wonder if the pump is too weak to overcome the lock. I don't know..it has me completely baffled and extremely frustrated.

I'm tempted to just replace the pump and insulate it and the pressure line with heat shield. I don't know what to do anymore.

 

A check valve in the fuel pump may be acting up causing problems, too. To me it sounds like the fuel pump if all else is good.

 

This is on the 84 w/a 460? Do you have the hot fuel handling setup? Ford had similar problems from what I've read and that's why they added that feature.

 

He said it was originally a 351W truck, so no hot fuel handling here.

 

^ Correct. This truck was originally a 351W and I swapped in a 460 when I restored it. I don't have any provisions for return lines on the senders or switching valve. I drove the truck for years this way and never had any trouble with vapor locking until this started last year.

 

Headers? Something is causing LOTS of heat, and the latest fuels don't help. I forget, have you tried 100% gas? Around here we can get it easily, although it is a bit more expensive.

If that won't work then you need insulation and maybe rerouting the fuel lines. Or an electric pump to get that further away.

(Btw, let it be noted that I didn't comment on "I swapped in a 460 when I restored it." I didn't want to start another battle so I didn't mention it. Or, " I mentioned it once, but I think I got away with it all right.")

 

I would insulate the lines.
It sounds like you have no other option.
Are you sure your tank socks are clean???

The reason mechanical pumps have such problems is that the pump is sucking all the way back to the tank.
Low pressure=low boiling point.
In tank pumps keep 5-7 lbs of pressure on the fuel in the line.

This may not sound like much, but with "fuel" the vapor pressure is so high it makes a big difference.
BTW, ethanol has a lower vapor pressure than most constituents of gasoline.

 

I would verify fuel pressure and flow rate as the first thing.

The factory provided steel fuel lines to run the length of the vehicle, short rubber pieces were used to connect the components together. If the problem began as soon as those short pieces were installed, it stands to reason that something in the reassembly is causing the problem. it's kinda funny to see people throwing around possible reasons of this without any sort of substantiating evidence...

 

Any kind of 'evidence' has to come from the OP...

As for why Ford's engineers determined to install a mechanical pump return line, and then update to a complex electric pump system (again with a return line) it would stand to reason that the 460 had vapor lock problems even with the 'Hot Fuel Handling' system.
Otherwise there would be no reason for a .090" service part vapor separator "for field repair of vapor lock conditions"

The fact that Rowdy has a "new" mechanical pump deadheaded into the carburetor points to condition that had been addressed by the manufacturer in a number of ways on trucks that came with 460's from the factory.

If the pump is vapor locked you're not going to get any pressure or volume, anyhow.

He states that the carb is dry when the truck dies.
It's pretty obvious that there is no delivery when the engine compartment gets hot.

 

Amen! Gonna have to do some insulating and probably add some reflective material.

 

Reflective insulating velcro sleeve.

It might help.

But insulation only slows heat down, it doesn't eliminate it.

 

That's why I suggested the reflective stuff. Move things as far from the heat-producing items, insulate, and reflect. And, if headers are involved consider ceramic coating them as that gives a dramatic temp reduction.

 

It looks like he installed it a year ago...

 

Yeah, I installed the reflective heat sleeve on the line going into the pump from the tank last year, thinking it was vapor locking on the suction side. I'll have to get some to cover the metal line between the pump and carburetor and I also want to try to wrap some around the pump if possible. I don't know what else to do aside from dropping the tanks and adding return lines to the system. Strange how it worked without any problems for so many years.

No headers on the truck, I'm running stock manifolds. It has dual exhaust but both pipes run down the right side of the frame, nowhere near the fuel lines. I was running 10% ethanol for years but I tried filling up with straight gas and the problem persists. I've checked and double checked the routing of the hoses I replaced and they are exactly the same as before. If the problem is related to those hose sections its invisible to me. I did replace those hoses immediately after I took it out of winter storage last year, before I had even driven it because one of them started leaking as soon as I started it up. I'm wondering if the feds changed the gasoline formulation between 2012 and 2013 and if that possibly made any difference? I don't know...its obviously a vapor lock issue but I'm completely stumped as to why it never caused problems before this.

 

You don't actually have to wrap the pump. Just placing a reflector between the pump and the exhaust will help.