Technical Vapor lock filter = no gas?

I have been having trouble with boiling gas and vapor lock so I got one of the fuel filters (see pic) that is supposed to eliminate this problem. But what happened is as soon as the filter got hot it diverted most of the gas back to the tank. So I basically ran out of fuel with 1/2 a tank. I took that filter out and put the normal style filter back in and was able to drive again. Has anyone got experience with these filters? Did I hook it up wrong? I have 1/4” hose from the little outlet to the tank no restrictions or valves. Supply is 5/16” at 4 to 6 psi from a mechanical pump

 

@squirrel , have you used one of these return line fuel filters?

 

I believe there is supposed to be a restriction somewhere. Otherwise, it will bleed off all pressure.

Here's an old thread with @squirrel 's input
https://www.jalopyjournal.com/forum/threads/fuel-return-line.1124950/

 

Look at the filter. Can you see a tiny orifice in the 1/4" fitting? If not, maybe it's a defective filter?

 

Is it an edelbrock carb? Try a phenolic spacer between intake and carb

 

Don't know much about the filter but I was having a vapor lock issue on a 1970's chevy pickup. All stock running a sbc.
Someone, here on the Hamb, suggested that one solution could be a weak fuel pump.
So I installed a new stock mechanical fuel pump and the issue totally disappeared.

 

I never had much luck with those return port filters. They always seemed to cause more problems then they solved.
I'd see if you can relocate the fuel line into an area where heat doesn't get trapped and build up around the metal fuel line. Re-routing the fuel line away from hot spots cured 90% of the vapor locks I had. Old, hard rubber hoses might not leak gas, but they can allow air to be sucked into the fuel line. Boiling the gas in the carb can also be a problem, the phenolic spacer may help there.

 

I believe you still have a flathead in your truck, I seem to remember in a previous thread you had used a modern fuel neck to the gas tank, did you install a ventilated gas cap? if not that may be the reason for the vapor lock problem
HRP

 

This filter has no small orifice (see pic)
The gas tank is vented

 

Find a different brand of filter? or make an orifice, perhaps .050"

 

That’s what I am going to try. Just need to find something that won’t migrate down the hose.

 

Having a lathe to make parts like that is so handy....

but you could cut off a short piece of 1/4" bolt shank, drill a 1/8" hole in it most of the way through, then drill a smaller hole in it through the short remaining section. Put it down in the hose, and put a clamp around it.

 

Holley regulator with a return port mounted after the fuel pump before the carb, 3/8" metal return line back to the tank with the line in the sending unit bent away from the pick up so it doesn't aerate the fuel.
I did this on my (off topic) 79 Ramcharger with a Blueprint 408 stroker with a factory style mechanfuel pump. 105° day sitting in gridlocked traffic with no issues.
The restriction in those mopar (Volare) style return filters makes them almost useless. They don't allow the fuel to flow fast enough to cool it down.

 

Using a fuel return solved a vapor lock problem for me. GM used that system in the late ‘60s on big block Corvettes and air conditioned Cadillacs and I doubt they spent money on something that did not work. I had tried a new fuel pump, rerouted lines, carb insulator, rebuilt and updated carb before making a fuel return with a GM filter and 1/4” line.

 

Put a Holley carb jet in the gas line. A big one, like in the 90s. It might even screw into the filter nipple for added peace of mind.


Obviously on the return in case that wasn't clear.

 

I used a .025 mig welder tip in the return line with that filter. Plus I insulated the filter.

 

I think the return line was in the fuel pump.
Well in the 70 454 anyways.

 

You have the filter between the pump and the carb correct?

 

Thanks for that. I have mig tips

 

Yes a few inches before the carburetor

 

a problem going on for many years - yep, clothes pins low budget solution (?). have a '65 T- Bird, 390 standard, which is part of a notorious Ford boiling fuel problem. factory even plumbed a plate under carburetor that carries water to address problem. the big air cleaner covers carb with small air inlet. so, to limit potential heat problem put a aftermarket 2" air cleaner on autolite 4100 to expose body for some air movement around it and better air flow into carb. then used self wrap aluminum heat shield over fuel line down to fuel pump. no problems with a year of driving. could not use one of the phenolic or wood spacers offered.

 

If the filter doesn't have an orfice, you can get one of these from mcmaster carr in various sizes, .080 orfice works for me, just drill out an .063.

 

There is some "science" that supports the clothespin fix being effective for vapor lock. Wood is a decent insulator, and if you clip enough clothespins side by side along the length of the fuel line, it's really not much different than running the fuel line through an insulating sleeve or wrapping insulation around it.

Tell me I'm wrong.

 

I have been seeing issues with Off shelf
Brand fuel filter from Napa & other
Big box store
Metal & plastic , like the material inside will not flow the Fuel , like getting Water / Fuel logged .

 

Update…I put a.030 mig tip in the return line and ran it up the street and back a few different times not a bunch in a row. Had no problems and it was all looking good. Today I went for a run to look at another car only just over a mile away. Truck ran good scooting along at 50 to 60 most of the way then it died ran out of fuel almost at the house I was going to. Managed to coast along and into their driveway. Left it there while we looked at the other car and changed out the starter. When it was time to leave the truck fired right up and scooted almost all the way home but again ran out of gas almost at my house so I coasted into the driveway.
The gas tank is 1/2 full but I have no gas at the pump. So now when it cools off I am going to check the pump and the line from the tank and also check the tank vent.
I suspect the pump is bad but I never had any of these problems running a non return filter.

 

It’s possible the tank is a bit rusty so I have a fine stainless steel 80 micron mesh bag around the pickup and the pickup filter. I will also pull that out and check it. I am only getting red dust in the filter before the pump since I put the bag and pickup filter in the tank. Before that there were some fakes and grit getting to the filter.

 

Can you rig up an IV bottle to supply gas to the carb and then run a hose from the pump outlet back to the tank and watch the flow?
It seems it's either heat or flow if it takes a while to stop.

 

@Budget36 -
No. Cadillac had a filter separate from the fuel pump.
The Quadrajet has a bronze inlet filter.

1967 Cadillac shop manual: