Queston regarding Fuel Filter-Vapor Return Line

[GOPDiesel]

I'm having a big problem with the fuel filter/vapor return line. I have tried 3 new fuel filters, 2 Fram and 1 Napa. When these filters are installed, with the vapor outlet on the top, my rig will completely lose power and die under moderate to hard acceleration. I have a new Napa fuel pump and carb.

When I install a fuel filter that only has the outlet to the carb (no fuel return line nipple), the engine has all the power and does not die/stall under full acceleration.

What can be going on that will cause it to run properly with the wrong filter on it, or why is it dying under acceleration with the proper filter?

Can I just leave the hose for the fuel return line open or can I close it without any other issue?

 

[elwood blues]

Have you checked to see if your return line to your gas tank is plugged?

I'm not exactly positive about the rest of it, and don't want to give out bad gouge, I need to do a little reading first...

 

[GOPDiesel]

Dumb question, How would I do that without pulling the tank? AND, if it was plugged, all the fuel would go to the carb and I should be ok? All the fuel going to the carb has proven to work with using the 1 inlet, 1 outlet filter that works great?

Thanks, Pat

 

[IOPort51]

Here is another question, I think I know the answer to but will throw it out because I am not sure. Do you use a return line with a Weber carburetor? Do you need a return line with a motor craft?

 

[GOPDiesel]

I have not read where it is not required. I kept it "factory" OEM filter with the dual outlets. The Weber does not say to change it. The Chiltons Jeep book has it dual outlet.

Pat

 

[elwood blues]

Dumb question, How would I do that without pulling the tank? AND, if it was plugged, all the fuel would go to the carb and I should be ok? All the fuel going to the carb has proven to work with using the 1 inlet, 1 outlet filter that works great?

Thanks, Pat

The simplest way (although maybe not the smartest) blow air through the line.

If it is plugged it's not letting vapor back to the fuel tank. The reason you line up the fuel filter outlets one on top of the other is because where the fuel line runs (right by the engine) some of the fuel boils and turns to vapor. The bottom outlet (the larger of the two holes) allows the liquid fuel to flow freely and the smaller hole (on top) allows the vaporized (almost steam like) fuel somewhere to go and be recollected in the tank. Sucking vaporized fuel into the carb will make it stammer and studder.

Same deal with the single outlet filter, no where for the vaporized fuel to go, except into the carb.

Here is another question, I think I know the answer to but will throw it out because I am not sure. Do you use a return line with a Weber carburetor? Do you need a return line with a motor craft?

I know you need a bowl vent line with a motorcraft, I'm almost positive you need one with a Weber also.

 

[IOPort51]

I have not read where it is not required. I kept it "factory" OEM filter with the dual outlets. The Weber does not say to change it. The Chiltons Jeep book has it dual outlet.

Pat

but the chiltons book says nothing about Weber's.

It works with out the return and it doesn't work with it. sounds like a no brainer to me.

 

[IOPort51]

The simplest way (although maybe not the smartest) blow air through the line.

If it is plugged it's not letting vapor back to the fuel tank. The reason you line up the fuel filter outlets one on top of the other is because where the fuel line runs (right by the engine) some of the fuel boils and turns to vapor. The bottom outlet (the larger of the two holes) allows the liquid fuel to flow freely and the smaller hole (on top) allows the vaporized (almost steam like) fuel somewhere to go and be recollected in the tank. Sucking vaporized fuel into the carb will make it stammer and studder.

Same deal with the single outlet filter, no where for the vaporized fuel to go, except into the carb.





I know you need a bowl vent line with a motorcraft, I'm almost positive you need one with a Weber also.

The bowl vents to the PCV or the charcoal canister as the carter 2bbl does.
this is an interesting point I shall have to look at it better after sleeping for a few hours. :wasted:

 

[GOPDiesel]

This problem has me completely baffled. I installed a pressure gauge. 6 PSI going into the Carb, (1 outlet fuel filter)
using NO return line, RUNS GREAT. I installed a new fuel pressure regulator. I can dial the pressure to around 3.5, runs good, NO RETURN LINE.

As soon as I install the dual outlet fuel filter (have tried 2 Fram and 1 Napa), gauge fuel pressure wildly fluctuates or stays at 0. This is with the fuel return line hooked up.

I blew air through that line today, once with gas cap on and once with it off, no change.

I have almost said F it, and will probable just leave the fuel return line open or plugged.

Will plugging the fuel return line hurt any thing or be a safety issue?

 

[LongHorn]

This problem has me completely baffled. I installed a pressure gauge. 6 PSI going into the Carb, (1 outlet fuel filter)
using NO return line, RUNS GREAT. I installed a new fuel pressure regulator. I can dial the pressure to around 3.5, runs good, NO RETURN LINE.

As soon as I install the dual outlet fuel filter (have tried 2 Fram and 1 Napa), gauge fuel pressure wildly fluctuates or stays at 0. This is with the fuel return line hooked up.

I blew air through that line today, once with gas cap on and once with it off, no change.

I have almost said F it, and will probable just leave the fuel return line open or plugged.

Will plugging the fuel return line hurt any thing or be a safety issue?

IMHO no, I've been running that way since I bought this rig in 2005.

 

[bullpup10]

I also had an issue with the fuel filter with double outlets. I replaced all my rubber fuel lines from gas cap to carb and also the sending unit. Still it acted like it had vapor lock. Ran compressed air through my lines and no ristrictions. I finally got fed up with this and ran the fuel line directly from the fuel pump to carb and so far so good. I plugged up return line and left it until someone can explain to me why I need it now. I'm using an Edelbrock 500 CFM carb. I guess different mods cause different issues.