Heat + Gas = Problems

[G.M.]

I have had problems the past few years when it gets up in the 90s with vapor lock. I made the problem worse, in testing a new Teflon diaphram which started 2 years ago I installed a 2 1/2" oil filled 10 lb pressure gauge in the fuel line between the pump and carb. I brought the line out from the carb and curved it down with a shut off valve then curved back toward the rear with a T and the guage and back to the fuel pump. This is on a 39 with the radiator hose in the center of the head. The fuel line was now about 1 1/4" behind the hose. This heated up the fuel line pretty high in that area. Also the oil fillter was on the rear of the drivers head. This put a lot of heat back in the area of the flex line. The oil return came off the rear of the filter and curved down and went forward to the pan near the dip stick. This line was near the fuel suppy line and the flex hose connection and heated up the line and flex fitting. This car has dual exhaust and the fuel line up in the kick up over the left rear wheel is not to far from the exhaust. I ran the line between the outer frame and the inner where it is doubled and put an aluminum deflector up near the rear crossmember where the line heads over to the tank. Both exhaust tail pumps are about 1 1/4" from the rear corners of the tank. The tank corners were getting up to 110 and the rest of the tank was the same as the outside temperature at 85. I made 2 sheet aluminum tubes about 12"s long with 2- 1 1/2" flanges with 4- 10/32 screews along the flange that sqeezes the tube on the pipe. This looks like a long muffler clamp. Now the heat is pulled out to the flanges and the corners now are 85 degrees. This was just a shot in the dark but it really pulls the heat to the flanges. This corner heat would be much higher on a 90 degree day when the road surface temperature is probly 125. Also I have a Stromberg carb which moves the fuel line down over 1" lower then the Ford carb getting it down closer to the radiator hose. Today I moved the oil filter to the front of the head, this moved all that heat and the oil return line heat up front away from the fuel lines and pump. I made up new fuel lines and curved them up so the gauge now sits up were the bottom of the gauge T is about at the bottom of the air cleaner. The intake manifold surprised me, air and fuel is running through the run back in front of the fuel pump and the temperature on the intake right in front of pump gets well over 200 degrees. There is about 1/16" space between the bottom of
the pump and the intake reflecting heat to the pump. I took a peice of aluminum flashing material 3 X 6"s, folded it so it's 3X3 and shoved ends between the pump and manifold and that seems to pull the heat and lower the pump temp a little. I found out over a year ago on a 1,200 mile trip in 2 days at just about 100 degrees both days when I got into small towns or slower traffic I lost power and eventually stalled in traffic. I fooled with the pump and got going each time. On the second day I noticed if I was going over 52 miles an hour it ran good. At that speed enough fuel was running through the lines, pumps and carb to keep things cool. At slower speeds useing less fuel the fuel was in the pump and lines to long and got hot. On several occassions when it got real hot gas would flow out the top of the carb. This happened at the V/8 meet in Charlotte at 100 degrees and several other times. It did it a few days ago and I measured the fuel temp at the carb and it was 160. I took a lot of temperatures the past week and find if the fuel gets up in the 150 range it starts to vaporise and you will start to see bubbles in the glass fuel pump bowl at idle when the engine is above 190. Raced up a little with more fuel flow the bubbles stop. After moveing the components and getting things cooled down the brass fittings at the flex hose and carb plus the extra fittings I have plus gauge and shut off valve all seem to attract heat. The copper coated steel fuel lines next to the fittings are all much cooler. The 85 degree fuel seems to make it into the carb bowl because that stays about 116. When hot and fuel problems begin the fuel pump pressure drops. On mine the normal running pressure is about 2 1/2 lbs and holds steady with the double ball needle valve replacement. As the fuel gets up above the 140 range the pressure drops to 1/2 to 1 1/2 lbs with a big swing motion of the gauge. This is air or gas vapors. When shut down in this hot condition the heat continues to rise, the pump drops to zero and go's to a vacume condition. The heat gets higher in the line into the carb and in the carb it self. This is when gas comes out the accylerator pump on the top. It must just be the boiling of the gas, it is not pressure because the gauge is below zero. Also the fuel filter glass bowl empties, this could be the vacume shown on the gauge as the fuel is pushed back to the tank?

Here's some readings when what I would call the engine high normal warm 185 in 80 degree out side temp with the engine running. Flex hose fitting fuel line end 133, fuel pump houseing top 129, steel fuel line from pump 109, intake manifold in front of fuel pump 210, heat sink between pump and intake manifold 185, carb line 117, carb fuel bowl 120. The outside fuel line and fitting temps are from reflected heat from external heat, the 85 degree fuel from the tank is what makes the copper plated fuel lines cooler from the fuel flowing through them. I would expect the lines and fittings would be a little cooler on the highway with more fuel flowing through them. This explains a lot of posts over the past few years on many of the fuel problems reported. My conditions will improve when I get done doing some tests and put a standard pump to carb fuel line on. This line wants to be kept up as high as possible to avoid picking up heat. G.M.

[Old Henry]

I'm assuming that you took all of these measurements with the hood open. If so, the measurements would not be as realistic as if the hood was closed. I think they would all be noticeabley higher under a closed hood, especially if the hood was sitting out in the sun. That's when I always got vapor lock but not any more. An electric fuel pump installed back by the gas tank solved that nagging problem. I only turn it on for an instant to "prime" the mechanical pump if there is ever any hesitation and the problem is gone. Before that I carried a jug of water to pour on the fuel pump when it vapor locked to cool it down, condense the vaporized gas back into liquid, and away we went.

[Fordors]

Or you could just do a Jimmy Cagney in it. Old hillbilly trick was to cut a grapefruit, but not quite in half, then tie it around the fuel pump to insulate it. You younger guys may not get the Cagney reference.

[Mike in AZ]

hmmm...seems to be a belief that there is such a thing as vapor lock....used to be quite some discussion on the old 'Barn about it being a figment of our imagination....lol....Mike

[donald1950]

aint no such thing as vapor lock in these old fords, not since skip started rebuilding coils... have skip rebuild the coil and that will solve all your problems.....

[G.M.]

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There are a lot of variables that every one can't be detailed but this gets to the area of the main problem. I figured a few hecklers such as the one from Texas that changes his name from time to time would have their negitive comments. Moveing down the road with forced air comming in with the changes I made I won't have any problems at any temperature as long as there is no fuel line or pump malfunction. I'm confident NOW that even in traffic I won't get a fuel problem. As I stated the extreme extent of my problem was self inflicted mainly by the route of the pump to carb fuel line and oil filter location. This was good as it magnified the prroblem and made it easier to find and by the process of elimination get to the cause and cure of the problem. There were very few real vapor lock problems in the old Fords with the old gas. And as proven buy 100s of posts the break down of the insulation in the old coil was the problem. It took 20 or more minutes to change the fuel pump and in that time the coil cooled and the engine started. Since Skip started doing the coils 15 or so years ago posts the appeared every day about vapor lock almost stopped. Others that had the problem and resolved it with Skips coil report almost every time the vapor lock question comes up. Now the vapor lock problem is real and gets worse as the amount of additives like corn, etc are increased with talk of greater amounts being added. Armed with the information I posted Ford owners can at least look in the areas desribed and correct their problems. The whole problem boils down to keeping the gas below 140 to 145 degrees.
I don't have to take my time to posting my findings, I don't get and payments out of this and my car now runs perfect again. As I stated many times after derogitory posts from a few, if you see my name on a post just scroll on by it, you are not forced to read it. If it helps 1 or 2 others that's my purpose. G.M.

[donald1950]

GM, many of us already knew there were vapor lock fuel problems that were unrelated to coils especally with ethanol gas that has been around for several years. glad to see you are now on board with an understanding of the problem.

[Shadetree]

GM,
Speaking for myself, please continue posting your findings on Fordbarn. Today, my old Ford is running cooler and more reliable, thanks to you and Skip Haney You just went to a lot time and effort to get this to us, you didn't have to do it. Keep them coming...

Shadetree

[Vic Piano]

George, I agree with Shadetree, and thank you for all your efforts. Unfortunately there will always be the naysayers and “know-it-all” that cower behind the anonymity provided by the internet. Vic

[34billct]

Thanks GM for your insite. I was in Charlotte in that heat with out problems thanks to Skips coil and to having my manifold heat blocked off, and I think it helpes to have single exhaust as ford did not run the fuel line and exhaust on the same side IE 33 -34 with 4 cyl. fuel line ran down right hand side of car.

[Old Henry]

G.M. I would be interested in seeing a picture of your engine compartment showing all of the replumbing, baffles, and shields that you have installed to deal with this problem. How 'bout it?

[G.M.]

I misplaced my camera when I find it I'll take some pictures. Other than the piece of aluminum shoved down between the pump and intake is the is the fuel line with the gauge. I don't think the stock fuel line from pump to the carb will create a problem but if problems occur it is an area to check. The only thing I didn't mention is I took one of Skips turbine impellers and put a taper bore in it they same taper as the little round part that sticks up on the pump. I just pushed that on by hand with the impeller blades up and don't know if it disapates or attracks heat I'll check that out later. Friends say it looks cool. It was only 80 F out today but it ran much cooler in the pump, line and carb area with the air flowing through the engine driveing it than it did in the shop yesterday sitting still. I usually put a fan in front of the grill when doing static tests but the water temp never got over the low 190s so I didn't bother. I don't think you could get specific temperatures like on the cooling system on the gas supply system, there are to many varables. The main thing to check on real hot days just when you stop driveing would be the fuel bowl area of the carb. This where it has to get hot to boil the gas over in the carb makeing it low on fuel when starting. I stopped several times today when it was 180 and it started like it did a few years ago on one turn of the engine. It took 10 or 15 seconds to start with the air, fuel vapor problem. Once the problem starts it looks like the fuel gets a big void as can be seen with low or no fuel in the glass pump bowl I said to my friend Jim who helps me that that you could screw around for a long time fixing and changing parts because of this simple problem. This covers hard starting, missing and lose of power and carbs running over. I think we have seen a lot of this lately on here. This don't mean every problem go's to the hot fuel but I'll bet a lot do. It feels good to get my old car back. G.M.

[Old Henry]

Originally Posted by Fordors

Or you could just do a Jimmy Cagney in it. Old hillbilly trick was to cut a grapefruit, but not quite in half, then tie it around the fuel pump to insulate it. You younger guys may not get the Cagney reference.

The one that I know of that several old timers swear by is clipping clothes pins along the fuel lines that either insulates them or dissapates the heat from them or something else. I didn't like the looks of that so I'll stick with the electric back-up fuel pump. No modification of the stock/original appearance and function of the engine compartment. All looks the same, just works better.

[B_man_Al]

As far as I'm concerned vapour lock is REAL. I have an old 1971 Triple E motor home with a SBC 350 in it. Years ago the previous owner was so pissed off with the fuel problems he was having with the stock mechanical pump on hot days, he replaced it with an electric pump located as far back as possible to one of the tanks. This helped but not completely.

After I got the unit, I added a second pump, back near the other tank with a switch to allow me to switch between the two electrically. After cruising for a while on hot days, the active pump starts to run continuously rather than just in short spurts based on fuel demand.

When it gets bad enough the motor home quits unless I switch to the other pump. Back and forth gets me home.

I have long since retired the motor home, but I put one of the pumps on my model B because of the same problem. It too quits on hot days and acts the same as it did in the motor home. It's not back at the tank, but rather near the steering box (I rerouted the fuel line to the left side to avoid the crossover of the fuel line and the exhaust back at the rear cross member).

I replaced the old pump with a new delco inline pump which quit after a summer of driving. I'm now running on a second delco, but I think I will relocate it to the back of the car to improve the temperature margins.

[Shadetree]

I have never had vapor lock on any flathead Ford I have ever owned. But when I would try to start my `35 after it sat for 15-30 minutes it would have to crank several times before it started. Once it started and ran I could shut it off, bump the starter and it started immediatly. I knew it had to be something to do with fuel. I installed a 97 Stromberg rebuilt by Ken Isidor and put a flexible fuel line with a check valve. It cured all of my problems. I really like the 97.

Shadetree

[G.M.]

Al, You need to buy a laser pointed thermometer and find where the fuel is getting heated up. Look at the lines, fittings and the bowl of the carb. I'm finding if the fuel parts are kept away from hot items and the tank and lines are away from the exhaust pipe the cool fuel from the tank going through lines, mechanical pump on it's trip the carb stays somewhat cool. For instance I found today 85 degree tank temperature providing 85 degree fuel through the system after driveing at 80 degree out side temperature and the water temperature at 180 after relocateing the parts described keeps the fuel bowl temperature in the 115 range in the carb. Don't forget the heat risers and the intake manifold are heating the carb but the gas keeps the bowl and jet area cool. [email protected] makes a phonalic ventilated carb spacer that reduces carb heat. This comes with longer studs and gaskets. I don't have one, mine has a Columbia vacume plate under the carb. It's aluminum and may not help much. When the bowl temperature gets into the 140 range the gas boiling in the carb starts. We may get a little carb venturie cooling, this area can get ice on it under certain conditions. I haven't seen any cooling effect in this area the few times I looked. Also keep in mind the engine temperature rises after shut down, the hotter the engine the higher this temperature go's. Places along the fuel route that get hot are heating the fuel so when it gets into the carb bowl there is no cooling effect and the hot base of the carb adds to the temperature of the warm gas entering the carb. No electric pumps for me I fixed the problem and as you stated if it gets real hot the problem is still there with the electric pump, in your case pumps. G.M.

[FL&WVMIKE]

I believe most "vapor locks" are, actually coil problems, but vapor locks do exist !
One time, during a hot, slow parade here in Florida, my car quit, but I could start it by pouring gasoline down the carburetor, but it would quit again, just like it was out of gas. I actually saw gasoline boiling !
MIKE

[B_man_Al]

G.M. I did do similar measurements as you suggested with a digital thermometer to see the variations along the way. Unfortunately I didn't write them down. One of the big questions to sort out is what is the boiling point of gas? Seems it can be anywhere from 100F - 400 F depending on the additives. This is further complicated by altitude and the actual fuel pressure in the line and carb. Ethenol is even worse, and the blends change from season to season as well.

Hard to say what the right (safe) fuel temp is ... maybe there isn't one because of all the variables.

Al

[G.M.]

I found with the new 85 ethenol I purchased a week ago if it gets to 150 F you have big problems. I looked up the boiling point as you did and got the big spread like you did. My temperatures are what I read. I also read summer and winter gas temperatures vary. You need to take temperature again there is no room for guess work with this gas problem, you need to know exactly what the temperature is. G.M.

[jimTN]

Yes, vapor lock does exist. My 32 will conk out on hot days and need a boost from the elec pump. You can hear the gas perkulating in the carb. Have added extra gaskets under it and those have helped. I have a 29 Packard that also vapor locks and you can see the gas boiling in the sediment bowl. I did some of GM's tricks with it, adding baffles and insulation around the gas line and exhaust pipe which helped. I believe it is the gas entirely. I drove my stock 39 Ford Std in Hawaii for three years and never had a problem. Drove flatheads back in the fifties with no problems here in TN but did have problems with the 49-50 Olds cars.