1956 Vapor Lock with Dual Outlet In-Line Fuel Filter?

[tovigba]

I apologize in advance for posting yet another vapor lock question, but this has got me stumped. To remedy the issue, I replaced the stock glass fuel filter with a WIX dual outlet in-line fuel filter which returns excess carb fuel to the gas tank through a copper line that feeds into what was the gas tank drain plug opening. I filled the gas tank, drove around 12 miles on an 85-degree day and parked for an hour. Restarting the vehicle took a couple of try's, drove around 1,000 feet, then engine coughed and died. Got a tow home and then the next day the car started right up. This is almost exactly what happened with the old glass filter, and hence the vapor lock issue still seems present. I was told that the WIX dual outlet in-line filter system would eliminate any possible vapor lock. So, my question is why I would still have the issue. I am speculating that the gas tank being full is restricting the excess fuel from readily returning to the bottom of the gas tank through the drain plug hole? (Note that the gas cap does have a small venting hole). Or my fuel pump is not delivering enough fuel pressure for the dual outlet system to properly function? Anybody ever heard of this happening with a dual outlet fuel system? As always, thanks all.

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[Buzzy]

If you have the dual line fuel pump you do not need the filter with the return as that weakens the pressure to your carb. Do you have a heat spacer between your carb and your manifold? My Lincoln had same problem, the spacer fixed it.

 

[tovigba]

Interesting, I will ask my mechanic about a heat spacer between the carburetor and the manifold. Thank you, this is helpful. Off the top of my head, there is a single fuel line going into the dual outlet in line filter. I’m also going to ask my mechanic to determine if there’s enough pressure going into the filter. But again, the heat spacer is an interesting idea.

 

[dunnedom]

I had the same problem . Thinking it was vapor lock. It turned out to be the gas cap had no vent and was causing a vacuum in the tank starving the pump for fuel. Removed the cap and the problem was solved. Hope it's as easy for you. Good.luck!

 

[dunnedom]

By the way. I did the same . 2 outlet fuel filter, carb spacer. Same problem until I removed the gas cap. Car would run about 15 minute and start sputtering eventually stalling out until it sat for a while.

 

[Lmarsch56]

I also have a 1956 with the 312 and I'm having a vapor lock issue as well. This is only my second summer owning the car. My issue is the vapor lock is at the fuel pump not the carburator. When it dies, the glass fuel filter bowl is empty. The only things I've tried so far is insulating the fuel line and adding a phenolic spacer between the fuel pump and engine which did not help. I can start it again after cooling down fuel pump and priming the carb. My next plan is the use straight recreation fuel without methanol since it takes a higher temperature to vaporize pure gasoline.

 

[simonsma]

I've had the same problem of vapor lock with my 1955 Thunderbird. Put the phenolic spacer in the carburetor, insulated the fuel lines and even ran with the hood up off its latch to get home. None of this really worked I finally installed an electric fuel pump down by the frame. I located it where the two fuel lines meet and did not cut them but took out the spacer and I used the new rubber hoses that are alcohol resistance that go into the fuel pump to give flexibility I'll try to include a photo I put a momentary switch in so that I could reach up underneath the dash and energize it to pump through when the vapor lock would happen this worked for a while but on real hot days I found out that I had to keep it on all the time so I put a switch down underneath the seat hooked up to the ignition that I can turn on and off and on hot days I just leave it on and let the fuel pump run that solve the problem I removed the insulation from around the fuel lines as I did not like the look it works great n.ow.

 

[simonsma]

Fuel pump located on frame without cutting fuel line just remove the spacer and use the flexible fuel lines that go to the fuel pump that are alcohol resistant.

 

[Texas TBird]

ditto simonsma's fixes, plus use only [U][SIZE=4]non-ethen[/SIZE]ol[/U] gas, I run both original pump and the electric as well, and a simple switch underneath the dash for safety. Like simonsma, I still keep the electric pump on all the time. Has worked all these 100+ degree days in Texas. One more thing, my 1955 has a six blade fan, I've heard that is pretty important as well. Oh yeah, I still have a wooden clothspin mounted on the gas line for good luck (like the old-timers)

 

[Bruce Hardy]

I believe all those vapor lock problems are because the gas cap is non vented. Change the cap and your problems are solved.When the tank is full, on hard acceleration you might get some spill so wait till you use a little gas first.

 

[tovigba]

Thanks Bruce, the cap has a small hole in the middle, so I guess it is vented already. Thanks again for the help.

 

[Tom Alpers]

As a data point you might use for troubleshooting this issue. I do not have any vapor lock type issues since I got my fuel pump rebuilt, before that it was having "vapor lock" type issues even in mild weather but I think it was simply "not enough fuel delivery" rather than "too hot". I have been monitoring under hood temperatures on my car for a couple years as I worked on getting it to run cooler after putting AC in it.
In regard to the issue in this thread... I have measured (using a temperature "gun") the temperature of my fuel pump and attached gas lines and filter several times including when the engine is running with AC on immediately after coming home. I pretty consistently get 175 F on the pump, the lines, the metal and glass filter. I can see some vapor in the glass bowl but never have any vapor lock. If you have a temperature gauge you might check to see what you get on those parts. Based on my experience, if it's not beyond about 175 it would not be temperature alone that is your problem.

Another thing to consider is your timing. Even if you have a good enough cooling system to keep the car from overheating, too much advance will make the heads run much hotter than they otherwise would which will increase intake manifold heat, which will make the carb hotter. Regardless of what you believe these cars *can* be run at for advance, consider setting the advance back to stock or near stock while troubleshooting vapor lock issue. When I had my timing advanced based on what "experts" were saying my heads would be running around 250 degrees. I dialed the advance back and now they run about 230.

 

[tovigba]

I also have a 1956 with the 312 and I'm having a vapor lock issue as well. This is only my second summer owning the car. My issue is the vapor lock is at the fuel pump not the carburator. When it dies, the glass fuel filter bowl is empty. The only things I've tried so far is insulating the fuel line and adding a phenolic spacer between the fuel pump and engine which did not help. I can start it again after cooling down fuel pump and priming the carb. My next plan is the use straight recreation fuel without methanol since it takes a higher temperature to vaporize pure gasoline.

I think my next step is electric fuel pump. BTW, I like the thumbnail of your 56 peacock blue bird!

Fuel pump located on frame without cutting fuel line just remove the spacer and use the flexible fuel lines that go to the fuel pump that are alcohol resistant.

Thanks for the pics. Very helpful. My mechanic walked me through troubleshooting tests I should perform the next time the car shuts down. He said he has installed hundreds of those fuel pumps, but he’d like to see if it might be an ignition problem, speculating that the coil may be getting too hot and then failing until it cools down. I was running the coil without a ballast resistor. The Pertronic 1282 electronic ignition calls for 1.5 ohm resistance an my generic brand coil is rated at .7 ohms. I installed a .8 ohm ballast resistor so I am now getting the recommended 1.5 ohm resistance resulting in between 6 and 9 voltd going to the coil. This should cool it down. But next time I have vapor lock I will be sure to have test equipment to troubleshoot where the issue is coming from. Thanks again, Barry

 

[Bruce Hardy]

It still might not be vented prperly. When the condition happens again, get to the tank as quick as possible and remove the gas cap. If nothing happens,that's not the problem but I think your gonna hear a lot of suction sound. I've seen those caps with the hole but ther're still not vented. Good Luck.

 

[SHA BOP]

I have owned my 1955 TBird since 1987 and never had a vapor lock. My TBird is completely stock. I have seen many complaints regarding vapor locks. I agree with Bruce that the problem is most likely simple and caused by the fuel cap. The cap is the most likely issue and the least expensive fix.
You may want to research some past forum discussions on this same issue

 

[doug7740]

The gas cap on your T-Bird must be vented to allow air to enter the tank. If air cannot get into the tank vacuum will be created which can stop the flow of fuel to your engine.

Last summer, I had to replace my gas cap, and I discovered that when I removed the gas cap after running the engine for a while, I could hear the sound of air rushing into the tank. To vent the fuel tank, the 1955 and 1956 gas caps have a rib stamped into the surface which allows air to enter from the outside edge of the cap to the center. The problem with my gas cap was that the inside diameter of the gasket was so small that it prevented the venting process.

The problem was easily fixed by removing the gasket from the gas cap and increasing the inside diameter of the gasket by cutting it with a razor blade.

doug7740
1955 Thunderbird Blue

 

[tovigba]

Thanks Doug. If that is the correct stock gas cap, then I think mine may not be - I will check. But what I am learning is that vapor lock is a chronic issue with many dollars spent on fixes and creation of unique home made remedies. Each of these baby birds seem to have their own personalities, likely due to aging of components and prior owners tinkering not now known.