Fuel System: VaporLock Ruminations...

[reichsrundfunk]

Hi Gang,

I recall a few weeks backs seeing something on VaporLock on one of the forum lists but damned if I can find it again, so I apologize in advance for repeating a subject:

My 63 Lark (with 253 V8 & 2Bbl carb) has begun exhibiting Vapor Lock issues now that the weather is warming. I exhibited it a bit last summer shortly after I bought the car but for some reason it seems worse this spring. On Thursday it was 81 degrees outside and during a drive of about 55 miles both interstate and county roads, the temp gauge was running between 190 and say, 205 and after each full stop, as I was accelerating the engine would exhibit the usual starving for fuel symptom of Vapor Lock. At one point it died completely and I pulled to the side of the road, popped the hood and let the engine cool down a bit. I also removed the fuel line from the filter and sucked up gas (yum) to get liquid fuel up into the lines again past the vapor. A couple times of that and she restarted just fine, but again after the engine temp went over that magic 190-200 point I had to be careful accelerating after a full stop to prevent it from dying out. I did stop to do some shopping for about 2 hrs and left the hood up. After that she drove home just fine the last 4 miles. It exhibited the same issue again yesterday just driving around town locally, showing some slight symptom of fuel starvation as the temp gauge hit about 205 degrees. So right now I don't feel comfortable driving it anywhere till I get this corrected.

It seems that the fuel begins to vaporize and the pump has difficulty pumping gas when the temp gets up over 190-200 degrees. Below that she runs like a Swiss watch.

Now I recall some years back experiencing the same issue with a 1951 Land Cruiser I had with the V8 engine. In that car the fuel pump was located on the top of the engine so it was especially susceptible to heat exposure. What I did to fix the issue was I installed an electric fuel pump ahead of the mechanical pump and ran the electric to a toggle switch I concealed under the dash. As I was driving if I felt the engine begin to starve for fuel I'd just flip the switch and within two seconds I was thrusting ahead good to go. I'd typically leave the electric on till I reached my destination or if the engine temp cooled down to where I would just switch the electric pump off. I'm thinking this is the way to go with my Lark. Running the electric pump pressurizes the fuel line as well as forcing liquid gasoline forward and preventing the fuel from vaporizing at that lower 190-200 temp range. I know its due to the damned Ethanol in the fuel..........

So, here are my two thoughts on this and I'd like to see what you experts think is the best way to proceed: should I stick to my original plan and install an electric pump ahead of the mechanical pump (which by the way was replaced last September so its fairly new) and switch it on only when needed to pump gas forward to the mechanical pump, or should I just bypass the mechanical pump entirely and use the electric as the one and only fuel pump, with it wired thru the ignition? The mechanical pump is supplying gas at a rate of between 4 and 4.5 pounds to the filter and carb.

Incidentally, since replacing the mechanical fuel pump I find that the fuel line (and visible in the fuel filter) is dry after sitting overnight, and I have to crank the engine for a few seconds to get fuel pumped up into the filter and carburetor. After it starts its good all day. My old Land Cruiser had the same condition. Now, with my electric pump arrangement I had with the Land Cruiser, I would switch on the electric for a couple seconds and that would pump up gas into the lines and fill the filter & carburetor bowl. Then the engine would start virtually instantly when I hit the starter, no cranking to bring up gas.

Thanks guys,
-George-

[starliner62]

I feel your pain. I have one car that exhibits the same problem. The first thing I found was the heat riser staying closed. The fuel would boil out of the carb. I "adjusted" the heat riser to stay open and that helped. Next, I replaced all of the rubber hose that someone installed instead of the steel line with new steel line. It has improved, but like yours, a long traffic light will make it want to vapor lock.
My son's 58 was doing the same thing and I replaced the fuel pump with a modified Mopar unit. He drives his daily with no issues.
I'm thinking about an electric pump for the 55, but I have to find a 6 volt pump.
Make sure you timing is where it should be. That will also cause more heat if not correct.

Good luck.

[53commander]

If you decide to go electric only do not just hook it to the ignition. If there is an accident the pump can stay running which could turn out very badly. Running it through the starter signal and oil pressure switch will allow you to have fuel pressure while cranking and when the oil pressure comes up. This is not only the safest way but will also shut the fuel off if the engine loses oil pressure. Here is the switch you will need http://www.amazon.com/Airtex-OS75-Oi.../dp/B0027I8CU8

[reichsrundfunk]

I feel your pain. I have one car that exhibits the same problem. The first thing I found was the heat riser staying closed. The fuel would boil out of the carb. I "adjusted" the heat riser to stay open and that helped. Next, I replaced all of the rubber hose that someone installed instead of the steel line with new steel line. It has improved, but like yours, a long traffic light will make it want to vapor lock.
My son's 58 was doing the same thing and I replaced the fuel pump with a modified Mopar unit. He drives his daily with no issues.
I'm thinking about an electric pump for the 55, but I have to find a 6 volt pump.
Make sure you timing is where it should be. That will also cause more heat if not correct.

Good luck.

Kanter Auto Parts in Boonton, New Jersey has them for 6 volt, both positive and negative ground.
-George-

[TWChamp]

OK, here's the scoop on electric fuel pumps. I drove my 50 Champion to Michigan last September and got stuck with a tank of corn crap gas that took out my new fuel pump, so I had to go to O'Rilley's to buy a 6 volt Precision brand electric pump for $53. This got me home and worked fine, but a couple weeks later I bought two 12 volt Holley electric fuel pumps for $5 each at a swap meet. The Holley put out 14 pounds of pressure and way more volumn than needed, so I used a 50 watt aluminum cased resistor to drop the voltage. I did a lot of experimenting in the kitchen by using different resistors to find what was best to get about 3 pounds of pressure and a good fuel flow. I found that the 12 volt Holley with a 4 ohm resistor worked great on a 6 volt battery. This reduced the voltage to 2.7 volts on a 12 volt pump.

Yesterday I took my Champion out for the first time in 7 months and found I had to decrease the resistence to 3 ohms before the pump was running. I suppose this was mostly due to the 6 volt battery being over 10 years old and getting a bit weaker. Anyway today I will replace the 4 ohm with a 3 ohm 50 watt resistor. I like using the reisistor because it drops the current draw plus makes the pump run slower and last longer. Also the pump has no rubber parts to be damaged by the corn crap gas.

I like to stay completely original and if we ever get rid of the crap gas I will buy a new mechanical pump to put back on, but in the meantime this does a great job, and as mentioned earlier, you don't have to do a lot of cranking to prime the carb. For some reason my carb goes dry after setting a couple days. I've had the carb apart at least 6 times and never found a fault. I even had it in my kitchen full of gas and setting over a bowl for two days, and not one drop of gas leaked out, so I can only guess the engine heat evaporates the gas.

OK, the bottom line is you don't need a 6 volt pump for a 6 volt battery. You can do as I did and buy a 12 volt pump and a resistor to drop the voltage to 3 volts. If I used the same pump on a 12 volt car I would need a higher ohm resistor to drop the voltage to 3 volts, but it works great. Here is a picture of my 12 volt Holley on my 1950 Champion.

[jbjr]

Last week my 3R5 vapor locked up when I was stuck in traffic on I 84 in NY, which was the first time in 3 or 4 years it happen. My temp gage never went up much past the mid point before. The only thing I could think of was that in my last oil change I switched to Valvoline from rotella. Today I hit the same traffic jam and the temp gage stayed close to mid point and no vapor lock. I am thinking that the Valvoline ran a bit hotter in my engine, that along with the outside temp which was the same as today caused it.

[jg61hawk]

They say a pint of diesel fuel in a full tank will really help. Seems scary to me so I double dose a full tank with Marvel Mystery Oil.. it really helps me.

[studebakerkid]

TW Champ....you sure do things the hard way. This has been covered multiple time. The problem is that ethanol boils at 173 degrees F. When running a mechanical pump you must have the heat shield in place and even then odds are you are going to have problems. NEVER install an electric fuel pump upstream of a mechanical pump because when the fuel pump diaphram gives out you will wind up pumping fuel into the crankcase and if you do not catch it in time there go your bearings.

I have run a mechanical pump before the electric pump and put the electric pump on a seperat switch wired from the ignition termoinal of the ignition switch. I also install a fuel filter with a return line tap and run a fuel return line to the gastank. I pull the fill neck and weld in a nipple for the return line.

I also have run dual electric fuel pumps in parellel that way if one pump goes out the other pump will get me home. It is also possible to run an electric fuel pump parelell with a mechanical one by using some miniature ball valves so you can sut off the inlet and outlet to thge mechanical pump in the event of mechanical pump failure.

The easiest thing to do is run dual electric pumps.

Now to TW Champ running that monster holley pump all you had to do is install a fuel pressure regulator down stream of that Holley pump and then run the return fuel line from a return fuel filter. I ran one of those Holley pumps on my T cab it worked fine.

[dickeedee]

I've been going thru the same issues since late last year with a '64 289.
I assumed it was a "vapor lock" problem, but after doing all the fixes,except for the return line...
I found it was a fuel pump problem. The pump was only a year old, but the ethanol
must have distorted the diaphram.
When it got hot, it would stumble out, and stall under heavy load.
The last time it did it,I sprayed it with a spritzer bottle of cool water, and it started right up.
I installed an electric pump back towards the tank , and when it stumbles, I switch on the pump for a few seconds, and it runs fine .
I plan to put in a rebuild kit in the mechanical pump, and keep the electric wired in for a back up.
I want to keep the mechanical pump because I don't trust either one to be trouble free.

[Tom Bredehoft]

The 'return line' is the solution to vapor lock. it allows the fuel in the line to circulate back to the tank instead of getting hot. just be sure you put a .040 restriction inline between the pump and the return line, so that the carb won't be starved for fuel.

[TWChamp]

TW Champ....you sure do things the hard way. This has been covered multiple time. The problem is that ethanol boils at 173 degrees F. When running a mechanical pump you must have the heat shield in place and even then odds are you are going to have problems. NEVER install an electric fuel pump upstream of a mechanical pump because when the fuel pump diaphram gives out you will wind up pumping fuel into the crankcase and if you do not catch it in time there go your bearings.

I have run a mechanical pump before the electric pump and put the electric pump on a seperat switch wired from the ignition termoinal of the ignition switch. I also install a fuel filter with a return line tap and run a fuel return line to the gastank. I pull the fill neck and weld in a nipple for the return line.

I also have run dual electric fuel pumps in parellel that way if one pump goes out the other pump will get me home. It is also possible to run an electric fuel pump parelell with a mechanical one by using some miniature ball valves so you can sut off the inlet and outlet to thge mechanical pump in the event of mechanical pump failure.

The easiest thing to do is run dual electric pumps.

Now to TW Champ running that monster holley pump all you had to do is install a fuel pressure regulator down stream of that Holley pump and then run the return fuel line from a return fuel filter. I ran one of those Holley pumps on my T cab it worked fine.

I don't understand your comments. The Holley is a small, quality pump and makes for a clean simple installation. The resistor drops the voltage, which drops the current draw, slows the pump for extended life, and gives the correct flow and pressure without having to buy a pressure regualtor and add more fittings and bypass filter, which would be more places to leak. The resistor cost less than $5 delivered to my mailbox. I have about $10 into my installation, which is also the answer to a dry carb, which otherwise would take a lot of priming. No need for a mechanical pump or backup pump. I can carry a spare Holley in the trunk and change it in minutes if need be.

I haven't seen any carb heat shields on the 50 Stude, but would try one if I can find one, or I might make one and try it.

[JoeHall]

Reading this thread brings back bad memories, which began in the mid 1980s, when it seemed every Stude I bought had vapor lock problems. I climbed a long learning curve and eventually discovered, short of EFI, there is no "one solution". Rather, the cumulative stacking of several remedies eventually minimized the problem: electric fuel pump, fuel return line, modern carb, wired open heat riser valve, clean motor block, HD radiator, 7-blade clutch fan, carb heat shield, and manual choke. All of those mods are on the 56J, and it has not vapor locked in a loong time, but still occasionally cranks awhile for hot re-start.

As for the two GT Hawks, both are EFI, and simply do not know what vapor lock is

[60ragtop]

Reichsrundfunk, I have a 60 Lark with a full time electric fuel pump and no mechanical pump and a 62 GT with an electric pump I control from the dash via a switch. The Lark was the first to get the electric pump. After almost being rearended as the car stalled on a major highway after pulling out of a gas station, I knew I had to do something. I decided to go with the "gerotor" style pump sold by Fifth Avenue auto parts. I installed the pump near the tank, and since the fuel line runs up the right side on these cars, decided to eliminate the line that runs along the front cross member and the mechanical pump. So now the fuel line runs directly up the right side and into the carb, which is an Edelbrock. The pump is wired through the oil pressure switch so it will shut off if the engine dies. One problem with this set up is a lack of redundancy, but of course we have that anyway with the stock set up. I found this to be a problem because the first pump failed one night and I barely made it home. Fifth Ave. (Randy Rundle) made good on the pump and the replacement pump has been on for several years without a problem. No more vapor lock, but I have noticed that it takes a while to crank the engine if the car has sat for several days, but this may be an issue with the Edelbrock. A teaspoon full of gas in the carb usually helps that problem.

With the GT, I installed a Carter in line pump and retained the mechanical pump. I forget the model number of the Carter but it's the one in various catalogs that puts out about 5 pounds of pressure and I got it at a local parts store staffed by old guys who knew what we were talking about As stated above a simple switch controls the pump. I switch it on to start the car after it's been sitting a while and it fires right up. The carb is the WCFB. So far I have not had to use it to control vapor locking but lately I've been using ethanol free 89 octane, which is available here in the Eastern Shore of MD.

As for the mechanical pump you are running now, I suspect it is faulty. In 2012 Wife and I were headed to the IM in SB in our 56 PresidentClassic (since sold, to my regret). Maybe a couple of months before, I pulled off a mechanical pump that worked fine but spewed oil from the weephole. When I bought the Prez in '07 a box of stuff came with it including a "new" fuel pump of a brand I never heard of (Hygrade). So I figured let's put this on and eliminate the oil mess. Bad decision. Taking off for SB I got about 60 miles and she started to exhibit symptoms of vapor lock. This in a car that had NEVER done this before. These got worse and worse, and eventually we were flatbedded home, never even crossing the Bay Bridge. Later, after not being able to get the car running in my driveway, it finally dawned on me that the fuel pump was bad. I bought a new rebuilt pump from Phil Harris and she ran great for the entire time I had the car. So I'd say even tho your pump is only a year old, it may not have the rubber parts that withstand ethanol and all the other stuff in today's fuels. Phil's have the latest stuff. BTW, we went to SB the next morning in a 2006 4 Runner, which was a bummer. One more lesson learned.

[BobPalma]

George: Does your '63 Lark (the OP topic) have power steering? BP

[reichsrundfunk]

No power steering, Bob. And thanks to everyone for their input. I have a 5-9 pound electric companies by and will install it this weekend. Will decid if it want to keep the mechanical online or bypass it. Stay tuned :-)