file:///C:/Users/Dan/Google%20Drive/1987%20Tioga%20RV%20(1)/vapor%20return%20w%20explaination%20on%20modificat ion.pdf

Sound like you have same problem as I have. I have a 1987 Fleetwood Tioga, 26 feet, 460 cid, 4BB holley.

When you get your new valve, blow on it with your mouth; see if it is restricted, if it is, don't install like I did (no longer returnable). If it is very restricted, DO NOT INSTALL !!!!. I make that mistake. Instead you may wish to do what I do.

This link may work better. https://drive.google.com/file/d/0B7i...it?usp=sharing

 

Note that the vapor canisters is not in the fuel delivery system and the fuel pump has no effect on fuel in the vapor canisters.
This would come from pressure building in the fuel tank(s) with over full fuel tanks.

You say fuel is even leaking back thru the carburetor.
Not sure what you are saying here but those carburetors can leak out of the end gaskets as my 83 class "C" did. To stop it i had to rebuild the carburetor.
You may also have a float that is stuck down after setting.

I modified my 1983 RV that had no electric fuel pumps stock and put a electric fuel pump in the tank (tank and pump out of a 1989 E-series) and one on the frame inline with the tank one and then thru the engine mounted fuel pump and had no problems with leaks. This system had no return to the fuel tanks.

If you put a fuel pump on the RV that was for a fuel injected system you would have a fuel coming out of the carburetor.

 

I realize your answer is intended for dtyrrell855. But I have exact same problem with my mobilehome-as dtyrrell855, so I make the following comment based on my experience.

Fuel pump was rated 5-8 PSI, not fuel inject pump.

Please, please do not mis-understand. I am not challenging your knowledge, I have greatest respect for you I am letting you know my experience with this.

 

If the vapor canisters leak fuel my guess would be that the engine is not purging the vapor canisters when the engine does run.

You still have not said where the carburetor is leaking at. Is the carburetor bowl over flowing?

I put that much pressure on my 1983 if not a little bit more and had no problem with the fuel at the carburetor. I had a fuel pressure gauge hooked on to the drivers mirror and "T" into the fuel line coming out of the fuel pump mounted on the side of the engine block.

 

I personally did not get a close look exactly where it leaks, However, the mechanic said the carburetor bowl; he then put the new gasket in. (carburetor was rebuilt by a pro shop a two months earlier)

 

Well...anything is possible, so all the info I'm gathering has got to solve the problem, one way or another.
You asked where the carb leaks...first, let me say that I rebuilt the carb not long ago, so gaskets and diaphrams are new and still good (hopefully), now to the leaks....not exactly sure if this is the only place, but it is the one place that is noticeable....it shoots gas out thru throat...it looks like 'Old Faithful Geyser"...and it has quite a bit of pressure behind it. The carb is def. getting too much gas. Since I am an "old" retired guy, I'll have to wait to purchase a new vapor separator (or whatever you call it)...and I will put a fuel pressure gauge inline with that to get more info. Hopefully the excess gas will bypass the carb and end up back into the tank...time will tell.
Another question....has anyone ever bypassed that entire system? Even if it takes adding a different carb? I was originally thinking of installing an Elderbrock on it...any ideas with that? This is the first time I've played with a 460, usually I play with 390, 352 and the old ford 427

 

here is my solution; https://drive.google.com/file/d/0B7i...it?usp=sharing

 

Just letting you know that the link you sent me, either doesn't work or my computer can not access it....

 

I don't see email address in your profile. I will try to send you an attachment.

 

Well...actually a few more questions about the fuel system and the vapor separator.
Once I replace the vapor separator (install it back into the system) and if the vapor canisters still overflow with fuel (and carb leaks). it is safe to say that the fuel pump is pushing too much gas. Does anyone have any idea how to dial down the fuel pressure? I think someone mentioned it before that they had the same problem. If that is so, what type of pressure regulator did you use and where did you purchase it.....I am so tired of this problem and just would like a solution to it. If anyone needs to send me diagrams of their solutions, send it to dtyrrell855@yahoo.com
I do appreciate everyone's help...and hopefully one day I can repay it

 

I have received information that a fuel pump manufacturer's technical representative said that they made two types of fuel pumps for the same tank for 80's vans. One put out 7-9psi for the carburetor type fuel system and the other put out 12-16psi for the systems that used two fuel pumps for the ones that had a fuel pump on the frame for the fuel injection fuel system.
I do not remember if those were the exact pressures but you get the idea of what he said.

I do not think putting a vapor separator in will solve your problem.
Also as I said above the vapor canisters are a complete separate system and the fuel supply system should have no effect on the Evaporative Emission System.