My 31 Imperial vapor Lock Saga

[Joao46]

Hello folks . 
 

So in an effort to correct my vapor lock issue, which shows itself by the car stalling after I drive it, park it and let it soak and restart it , shortly afterward it stalls and I have to let it cool off a bit.

 

I added one of those filters after the fuel pump that has a bypass nipple that I routed back to the gas tank. 
 

So now, the fuel pressure goes to between 1 and 0. The car starts and runs but it runs roughly and there is a lot of bubbling I see from the clear glass sediment bowl that is part of the fuel pump. Has anyone done this and experienced similar results? 
 

Here is an additional effect I noticed. I disconnected the return line and plugged the nipple. Now the engine runs smoothly again and the bubbling at the sediment bowl stops . 
 

I have never measured fuel pressure before and now I see that it is about 7 psi, and as the car warms it rises to 10. 
Then after a while it goes back down to 5. 
 

I am totally puzzled. I would expect the standard fuel pressure to be below 5. 
 

Any comment on my fuel bypass issue and / or the seemingly excessive and varying fuel pressure would be appreciated. 
 

I have the mechanical pump.

[Gearheadengineer]

Your return line has less restriction than the carb, so most fuel is flowing back to the tank and your carb is starving. If you must run a return line I think you should have some sort of pressure regulator in place. Which may not help with your vapor lock problem. Also, check the tank pickup and feed lines to the fuel pump for restrictions. 

[Frank DuVal]

38 minutes ago, Gearheadengineer said:

If you must run a return line I think you should have some sort of pressure regulator in place. Which may not help with your vapor lock problem.

The factory never ran a regulator when they used return lines in the 60s. But they were a smaller diameter than the line to the carburetor. Typically 3/16" line. I would just run a restriction in the return line. 

[ramair]

I agree with this approach, I am not sure if I would downsize the return line or perhaps adapt a fuel petcock similar to the type used under a SW vacuum tank, that way you could “throttle” it to create the proper pressure differential 

[Bloo]

Also those fuel filters with the extra nipple have an orifice in the third nipple. The diameter of the return line was indeed smaller, but it shouldn't need to be to function correctly.

 

 

Edited November 30 by Bloo (see edit history)

[Joao46]

Is my locating the filter with the return line between the carb and pump correct or should I locar it between the tank and pump?

 

Its sounding like what I really need is a pressure regulator between the pump and carb.

[EmTee]

How is the 3-nipple filter oriented?  The filter canister needs to be mounted vertically with the return nipple  pointing down in order to function properly.

 

[Joao46]

Per your drawing I have oriented the filter properly.

Ive been thinking and I really don’t see how this arrangement can work. 
All it does is pump the fuel back to the tank and prevents any pressure from building up between the pump and carb. 
Maybe this idea is wrong and what I really need is a proper fuel pressure regulator with a bypass. That way, proper pressure can be kept between the pump and carb with only the excess being pumped back to the tank.

 

Or perhaps I’m using the wrong filter? 

Edited November 30 by Joao46 (see edit history)

[EmTee]

In theory, the vapor separating filter should work.  I suspect the issue is that the '31 Imperial runs at lower fuel pressure than the cars the filter was designed for (i.e., 2 ~ 3 psi vs. 7 ~ 8 psi).  There probably needs to be additional restriction added to the return line.  Ramair's idea to add an adjustable restriction (i.e., valve) to the return line might be what is needed.  Adjust the return volume with the engine running (cold).  Start with the valve closed (i.e., no return) and then slowly open the valve until you see a drop in fuel pressure to the carburetor, then  close it slightly.  The return just needs to be able to bleed any vapor that accumulates at the top of the filter canister and push it back to the tank via the return line.

[Joao46]

That restriction idea sounds like it may work. 
Also, with the bypass plugged my pump delivers as much as 10 psi at times. Then at other times, 7psi.

[EmTee]

22 minutes ago, Joao46 said:

Also, with the bypass plugged my pump delivers as much as 10 psi at times. Then at other times, 7psi.

That sounds awfully high to me for a '31, but others who know better are welcome to correct me...

[alsancle]

 

1.  Run high test, it has a higher boiling point.

2. Thermal rap any fuel lines coming close to heat.

3. Did the carb have a factory heat shield?  It could be boiling in the bowl.

4. Is the fuel delivery line factory size?  A larger diameter line will help or eliminate vapor lock.

5. I'm assuming you have an electric pump based on the 10lbs.  That seems way too high.  It should not vapor lock with the electric pump enaged.

[Joao46]

I already run high test. All lines are wrapped and I only use the mechanical fuel pump.

[EmTee]

My astrologist swears by these... 

 

[Joao46]

I heard about those clothespins. Makes no sense. Wood is not a conductive material.

[m-mman]

Steel or copper fuel lines? 
copper transfers heat into the fuel much faster.  

[Joao46]

Steel

[Bloo]

8 hours ago, Joao46 said:

Is my locating the filter with the return line between the carb and pump correct

Yes, depending on what you are trying to accomplish I guess. These were between the pump and carb on every factory setup I have ever seen.

 

8 hours ago, Joao46 said:

Ive been thinking and I really don’t see how this arrangement can work. 

Me neither, if we are strictly talking about vapor lock. It helps a little, and gave me more "headroom" on one of my own cars years ago. What I mean by that is the outside temperature could be a few degrees higher before I had trouble. Did it solve the problem? No. The slight improvement apparently comes from the cooling effect of having a little fuel moving. It moves some heat into the gas tank. Probably not that much considering the size of the orifice. Also a mechanical pump continues to move fuel during times the float valve is closed. That probably helps.

 

8 hours ago, EmTee said:

How is the 3-nipple filter oriented?  The filter canister needs to be mounted vertically with the return nipple  pointing down in order to function properly.

 

For many years I used to believe that. I don't believe it anymore. Is that drawing from Buick or from Chrysler? I think someone is pulling someone's leg here. Riddle me this. Lets say that the car is vapor locked, and not running because there is no fuel in the carburetor. The carburetor's float valve is open, and it is up at the top! Why do we need to separate vapor? It would just go into the carburetor bowl and out the bowl vent.

 

It's sort of a trick question. Carbking once explained what these 3 legged filters are really about. He wrote it up too, and I would link it if I could find it. They are for the specific problem where fuel boils in the fuel pump on a hot shutdown. Once vaporized, the fuel becomes a "refrigerant" with it's own pressure-to-temperature relationship. What was once 3PSI or 5PSI (depending on the fuel pump spring when the fuel was still liquid) is suddenly much, much higher. The pressure has to go somewhere. Assuming the carburetor is full and the float valve is closed because you just shut an idling car off, there is nowhere for this pressure to go. It can't go back to the tank. The check valve in the fuel pump stops it. The pressure skyrockets, and blows any remaining fuel (in the line from the pump to the carburetor) past the float valve. The carburetor bowl runs over and the fuel goes into the intake manifold. The engine is not starved for fuel, it is flooded. It might not start. It probably won't start. The driver might make it worse by pumping the accelerator, assuming the car is vapor locked and there is no fuel. The third port, if present, gives that pressure a way out.

 

Edited Saturday at 09:04 PM by Bloo (see edit history)

[Joao46]

Thanks for all the advice. My filter was correctly mounted with the inlet and the return nipples facing down and the outlet facing up. 
 

But the car runs poorly like that with no pressure at the gauge and a mysterious bubbling seen at the pumps sediment bowl. As soon as I plug the return line, the pressure goes up (naturally) and the car runs fine with no bubbling at the sediment bowl. 
 

Another mystery is the 7-10 psi pressure. 
 

My plan is to get scrap the bypass filter, get a Holley bypass fuel pressure regulator that can be adjusted to 4.5-9 psi, set it to around 5 and see what happens. 
 

 

[EmTee]

4 hours ago, Bloo said:

The carburetor's float valve is open, and it is up at the top! Why do we need to separate vapor? It would just go into the carburetor bowl and out the bowl vent.

Good point; makes me think John ( @carbking ) probably knows a thing or three... 

 

I thought for a second about what would happen if the filter was placed on the suction side of the pump, but that makes no sense.  It seems the vapor separator is designed for fuel to be pushed through it and the 'hot soak' mitigation scenario makes more sense.

[carbking]

2 hours ago, Joao46 said:

My plan is to get scrap the bypass filter, get a Holley bypass fuel pressure regulator that can be adjusted to 4.5-9 psi, set it to around 5 and see what happens. 

 

In the "for what its worth category":

 

Stromberg specified the MAXIMUM fuel pressure for the DD-3 to be 2 psi.

 

Jon

[EThomas]

I had almost this exact problem on my ‘31 CM6. It was a massive pain to get resolved. 
 

Check your float. I’d lay money it’s cracked, probably a hair line at that.

[Joao46]

If it’s cracked wouldn’t it sink and flood the engine?

[Joao46]

12 minutes ago, carbking said:

 

In the "for what its worth category":

 

Stromberg specified the MAXIMUM fuel pressure for the DD-3 to be 2 psi.

 

Jon

Interesting that it seems to run fine with the pump putting out 7 and it’s a stock pump. 
Can you send me a pic of the spec?

[Joao46]

With this knowledge of the proper pressure, I can the get a regulator that regulates from 1-4 psi .

 

Thanks Jon

[EThomas]

14 minutes ago, Joao46 said:

If it’s cracked wouldn’t it sink and flood the engine?

I had the exact same issue and symptoms. It’d run, stall when it got warm. Cool off and it’d run fine again. Rinse and repeat ad nauseam. The fuel bowl would bubble like crazy as well. 
 

I replaced all the fuel lines - hard and soft. Heat shielded them from the frame inward. Rebuilt the carb. Cleaned the tank. Scratched my head endlessly. 
 

It was a fine hair line crack in the float at the end of the day. Damn thing took forever to find. 

[Joao46]

2 hours ago, EThomas said:

I had the exact same issue and symptoms. It’d run, stall when it got warm. Cool off and it’d run fine again. Rinse and repeat ad nauseam. The fuel bowl would bubble like crazy as well. 
 

I replaced all the fuel lines - hard and soft. Heat shielded them from the frame inward. Rebuilt the carb. Cleaned the tank. Scratched my head endlessly. 
 

It was a fine hair line crack in the float at the end of the day. Damn thing took forever to find. 

Interesting. Mine does not stall except after a long idle or driving after a hot shut down, which makes me suspect vapor lock.

But that’s good info. 
Were you able to get a new float or did you fix yours? 
If I need a float, I’m screwed.

[Lahti35]

14 hours ago, EmTee said:

My astrologist swears by these... 

 

I just showed my wife this picture, she looked confused. She asked what I was looking at so I told her the "theory" but she just looked even more confused...

[ramair]

I have been thinking, dangerous I know!

the above style filter with return line must be spliced in with soft rubber fuel lines, which is always a fire hazard! Last year a acquaintance of mine nearly lost a American Underslung as a fire started next to a filter and was melting the above mentioned fuel hoses, that car did not have a electric add on fuel pump, but it did have a onboard air pump that pressurized the fuel tank to 2 pounds.  Luckily a quick thinking guy released the fuel pressure . Another thing to keep in mind if you do insist on having rubber hoses for fuel lines look and make sure that they will not spray on anything hot or electrical if they fail.  Also keep in mind that the new gas formulation will accelerate deterioration on the rubber, so if you bought a car a few years ago and it came with a add on filter or during maintenance you have just wiggled on a new filter and not changed the hoses, you might want to spend some time thinking about taking care of some deferred maintenance. Another side note make sure that if you have any unused fuel hose on the shelf , make sure it’s the new material. I believe the improved material has some writing on the hose showing a high pressure rate, probably due to modern cars having fuel injection.

[Bloo]

Modern fuel is a wild card. In my opinion, use only 30R9 hose and fuel injection clamps.

 

[Joao46]

I’m confused, what would one use besides rubber hoses to carry fuel ?

 

One can maximize the use of metal fuel lines but there will always be a need for rubber hoses for some connections, especially where there is relative movement like between the engine and chassis.

 

Also, what’s a fuel injection clamp? 

Edited Sunday at 11:27 AM by Joao46 (see edit history)

[ramair]

17 minutes ago, Joao46 said:

I’m confused, what would one use besides rubber hoses to carry fuel ?

 

One can maximize the use of metal fuel lines but there will always be a need for rubber hoses for some connections, especially where there is relative movement like between the engine and chassis.

 

Also, what’s a fuel injection clamp? 

I have 4 vehicle that were built before 1940 and all of them came with copper lines exclusively.

each manufacturer solved the flex or engine vibration issue differently.  When did car companies start using hose? It would be an interesting conversation to have .  I do know that by the sixties most cars ran fuel hose from the gas tank up to the engine compartment on to the fuel pump, but from there it was always hard piped.  
  A fuel injection clamp is used on modern cars that have high pressure pumps, they have tremendous clamping power, hose clamps have improved a lot, for instance Oldsmobile in the sixties used a crazy little spring steel band that contracted to secure the hose, then came the small worm drive clamp, I don’t like those as the embed into the soft rubber hose

[Bloo]

32 minutes ago, Joao46 said:

I’m confused, what would one use besides rubber hoses to carry fuel ?

 

One can maximize the use of metal fuel lines but there will always be a need for rubber hoses for some connections, especially where there is relative movement like between the engine and chassis.

 

Also, what’s a fuel injection clamp? 

 

This is the most common type. Honestly they're kind of a pain to work with. The main qualities we are looking for is a nice round cross section, and not extruding the hose.

 

Yes, there just about has to be rubber somewhere. 30R9 is for high pressure and fuel injection systems. The main reasons it is interesting is that it is rated for a long list of fuels, including alcohol, and it is lined. In modern times, it is expensive but common.

 

The old hose used on carbureted cars back in the 60s and 70s was often found with pinholes and squirting fuel all over under the hood. I used to see that all the time. Now there is some evidence that ethanol laced fuel attacks that hose, as if it wasn't bad enough in the first place. It really is a wonder more cars didn't burn down. Unfortunately it is common for people to be still using that hose, cutting metal fuel lines, not swelling the ends of the tubing where the hose connects, using worm clamps, etc. Every half-assed connection like that increases the chances the car might burn down, even more so when there is an electric fuel pump.

 

You are correct that you probably can't get rid of all the rubber. You can probably get rid of some if it and use 30R9 for the rest.

 

 

Edited Sunday at 11:55 AM by Bloo (see edit history)

[EmTee]

FYI, last year I installed a spin-on water separating fuel filter on my boat.  I replaced the old hose with new USCG-approved fuel hose that I bought at O'Reilly's.  There are two types: (1) above deck and (2) below deck.  Since I have an I/O and the filter is in the engine compartment I bought the 'below deck' hose.  It is stenciled with the spec and the hose wall is noticeably thicker than even the so-called automotive 'fuel injection' hose.  I haven't used this on a car yet, but I would consider it next time I need to replace a section in a hard to reach area (e.g., passing inside or through the frame).

[Frank DuVal]

Miscellaneous thoughts:

 

1. The AC GF-99 fuel filter that was OEM on turbocharged Corvairs was mounted in the horizontal position. The early production did not have a return line, so no GF-99 filter, but there was an issue so production changed to a return line. What issue? Probably the gas expanding and pushing past the float/needle in the Carter YH. They really don't like above 5 psi or so.

 

2. I have now gone to the SAE 30R14 barricade hose for fuel hose on carburetor engines. 

 

3. I still use those simple spring band clamps on that hose. Or the #4 and #6 gear hose clamps as needed. We are not holding back 30 to 50 psi on carburetor systems, hopefully! (see #6).

 

4. I use the inverted flare flaring tool to make a bump on fuel lines. Just a little, just need a small disruption in the smooth surface . Or, use a "Push To Connect" die and just lightly to make a nice smooth bump. This is for a hydraulic tool.

 

5. Even a Holley pressure regulator like the 12-804 (1 to 4 psi) without bypass will run up to full fuel pump pressure when dead headed, like the needle is closed on the seat. I have confirmed this with people running them to regulate fuel to N2O in racing applications. They like the pressure to go high then come back down to setpoint. I do not want that!

 

6. I just replaced the simple AC design (1929) mechanical fuel pump on my 1984 F-150 six cylinder (300). Instantly the Carter YFA (think YF, or, a downdraft version of the Carter YH) looked like a lawn sprinkler! 😮🚒  So I put a gauge on the line and 18 PSI! I bought another brand fuel pump from a different supplier just to see, and that one is 22 PSI !!!!🤬🚒

 

7. We have been complaining in the Corvair world for years that the new fuel pumps put out too much pressure causing flooding. That is why I have fittings and gauges to measure fuel pump output. Yes, I have checked the gauges against themselves (4), and they all agree. 

 

8. The only thing that makes output pressure in an AC design fuel pump is the internal spring. No, the action of the engine's camshaft does not make the pressure, it just charges the internal spring. The Corvair carburetor is assembled with screws, so I just take the high pressure ones apart and cut the spring until I get 4 to 5 PSI output. Or install old springs out of the pile of used fuel pumps I have. 🤔  The newer pumps like the F-150 one are crimped, so no way to adjust pressure. Just return them. I installed an electric Facet brand 4-7 PSI to fix the problem. Runs 5-6 according to the cheap Amazon gauge and the YFA is dry as a bone. No more puddling fuel in the intake manifold! Seriously, it was a 1/4" deep when I would take the carburetor off.

 

9. The only cars I have worked on without rubber fuel line between the fixed frame/body and the engine had coiled copper fuel line. And copper fractures from work hardening, so not sure that is better....🤔  Ed has more experience, so I will go with what he says.

 

10. I like the look of running the electric at the tank and leaving the lines in place on the mechanical pump. But, you are depending on the existing diaphragm in that mechanical pump to keep gasoline fed by the electric out of the crankcase oil! Seen too many fail and squirt gasoline onto the engine and/or (more secretly) into the crankcase diluting the oil and there go the bearings. On Corvairs they sell a bypass plate, a machined section to replace the center section of the check valves so it looks stock, but cannot leak internal or external anymore. If your mechanical comes apart then making a section might be possible to keep the stock look. Then just install the working mechanical for specific shows. Put the blank one on for tours.

 

11. True vapor lock is when the fuel pump has fuel vapor in it. Typically from boiling fuel. The pump is good at moving liquids, but not so good at moving vapor. And, as it tries to move the vapor, any liquid boils and makes more vapor. This typically happens after the car is shut down for 10 or so minutes. It starts, uses the fuel in the bowl and stops, since the fuel pump is no longer pumping liquids. The quick fix (and troubleshooting step) is to ice the fuel pump. If it starts pumping fuel, then yep, vapor lock in the fuel pump. If there is simply vapor in the line from the pump to the carburetor, it quickly moves through the line, pushed by liquid fuel, since the needle will be off the seat, allowing flow of fuel or vapor. But not if the pump has vapor in it.

[nsbrassnut]

Some more comments similar to those above. But with some additional period literature information to consider.

 

There are a couple of items that concern me that may be worth some additional review. The comments have noted that the specified carburetor inlet pressure is 2-2.5 psig. And that the pump is putting out 7 to 10 psig. So perhaps before going down the path of pressure regulators, diversion filters, etc. what about going back to the basics of the pump itself.

 

 

I had some similar issues with a lack of performance on my Packard 120 a couple years ago. And went down the path of thinking that the fuel system was the main culprit. The engine idled poorly, showed wet fuel going into the jets and stumbles going down the road. And when testing the engine running with the pump discharge teed back portable tank on the floor it also showed what appeared to be bubbles coming out of the pump. I got so far as to order both an 6V electric fuel pump and a pressure regulator.

 

 

Without going into a long circular story, I’ll just say that the fuel system turned out to not be the issue.

 

 

Let’s go back to the basics of the fuel pump. First, I am assuming that it’s a typical lever action fuel pump driven from the camshaft. If not, then not of the following will apply.

 

 

I did some research in my library and found a description of the diaphragm pump fuel system design in a Dykes, c1933. That description does note that the maximum fuel pressure from the pump should be 2.5 psig. See the notes below.

 

Then when looking up similar fuel pump service information in later Motor Manuals, the charts show a trend to higher fuel pump outlet pressure starting in the mid ‘30’s continuing up to the mid ‘50’s.

 

My fuel pump had a rebuild kit installed years ago and it ran fine for many years. I also had a spare kit in the pile and took it apart for inspection and another rebuild. I didn’t find anything wrong with it, but installed the replacement parts anyway.

 

 

Then I started to figure out how the pump really works with some more reading. As described in the notes above, the diaphragm pump fuel outlet pressure is set and controlled by the spring that pushes on the diaphragm and not by anything else. I made a mount for my pump that I could put into the vise to hold it sill. Then hooked up clear tube suction line to a mini tank, and another clear line out and installed a pressure gauge on the outlet. Then by hand pumping the lever you can prime the pump and see what pressure it puts out. The pump will stop “pumping” when the outlet is plugged, like when the carburetor needle valve seats, even if you keep moving the lever. Next, just leave it sit and read the pressure gauge. It will read the pressure that the diaphragm spring is producing in the pump. In my Packard pump it was right on, about 2-3 psig.

 

 

 

 

If your fuel pump is a mechanical diaphragm pump like those above, I would recommend taking it off the car and bench testing it to see what outlet pressure it is actually producing when it stops pumping and sits against a closed fuel outlet line. If you pump and gauge shows more than 2-3 psig, then there is a good chance that the wrong spring is inside the pump. And since the later pumps were designed to produce higher outlet pressure, there is also a good chance that a “rebuilt” or a “generic” multi-year rebuild kit would have the wrong higher pressure diaphragm spring.

Just a suggestion to consider.

 

I should also note. At the end of the day the only thing I ended up changing on the fuel system was to slightly lower the carb float level (I live as sea level). That stopped the wet fuel in throat. The rest of my engine issues were not fuel related.

Edited Sunday at 09:33 PM by nsbrassnut (see edit history)

[alsancle]

Btw,  the symptoms you describe are very similar to what would happen if you had a bad condenser or coil.

 

A very smart guy once told me that 90% of all fuel issues were ignition.

[Bloo]

I would only add that making sure the check valves seal properly can solve a lot of problems before they even become apparent. If the valves must be "wet" to seal, the pump isn't going to recover quickly when it has been boiled dry. If the check valves seal and hold vacuum between strokes, the pump might recover before the carburetor bowl runs dry.

 

A mechanical fuel pump typically has one cam lobe working it, and that lobe typically runs at camshaft speed. Camshaft speed is half crankshaft speed. That means the engine has to make two full revolutions before the fuel pump gets another stroke. When your fuel pump is dry, can it hold vacuum at it's inlet long enough to get a second stroke, and a third, and a fourth etc. without bleeding down in-between? Can it do that it idle speed? How about at cranking speed? Brand new check valves typically can't do this until they break in. That sorted itself out when people daily drove their cars. I doubt many check valves ever get broken in today.

 

Yes I obsess over this detail. On the other hand I live where it regularly gets over 100F in the summer, and so far I don't need an electric pump to get me out of trouble like many of my fellow enthusiasts do. Admittedly if it is crazy hot outside, I always rev the engine up after a hot restart while there is still gas in the carb, to reassure myself the fuel pump is still primed. That is just one of those automatic things everyone did back in the days when we all drove carbureted cars.

[CTCV]

I solved my vapor lock issue completely by simply wrapping the metal line with header wrap. 
Tony

I also had a condenser issue that caused a symptom as if two spark plug wires were on the wrong plugs. 

[carbking]

I found this thread by searching on carburetor, noted the comment on fuel pressure, looked up the spec and posted, but at the time didn't have time to read the entire thread.

 

Now have read the entire thread. The stalling symptoms described by the OP are consistant with "hot soak", not vapor lock. Vapor lock, as mentioned by others in this thread, is defined as vapor in the fuel pump. While the pump will pump vapor, it is far less efficient pumping vapor than liquid.

 

Generally, hot soak can be minimized or completely eliminated by running the engine at a high idle (maybe 1500 RPM) for a period of time after the engine is started under hot soak conditions. Each engine will have its sweet spot, but normally 15~30 seconds will do the trick.

 

As to the rough running, 0~1 psi is insufficient, and is indicative of no restrictor or too large a diametered restrictor in the bypass line. If the fuel pump is putting 7 psi into the line which drops to zero with the use of the return line, GUESSING there is no restrictor at all in the bypass line. Installing a temporary pressure gauge at the carburetor should allow testing with different diameter restrictors to get the load pressure at the carburetor to 1.5~2 psi. Once the desired pressure AT THE CARBURETOR is acquired, the gauge may be removed. ALWAYS test! While the advice given on these forums is probably much superior to that of the local FLAPS folks; testing will confirm/deny the effects of the advice.

 

The restricted line, once tested and tuned for the proper pressure, should not need a regulator.

 

If you must install a regulator, get one with an internal bypass that feeds the bypass line. Again, install a temporary gauge at the carburetor to tune the regulator. Installing the gauge at the regulator will not show the pressure drop in the line from the regulator to the carburetor.

 

The "dead head" in-line dial type regulators are extremely useful for those with a strong arm, and a rabbit problem in the garden!!!!! (Opinion) they have absolutely ZERO use in a fuel system. They also make a nice conversation type paper weight if they are clean.

 

Jon