Vapor lock blues
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Well, it happened today. 101 degrees and a long grade equaled vapor lock on a steep hill. I had to get a tow to finish my trip. I could have waited for the engine compartment to cool down but I was on my way to relieve one of my workers for his lunch break so waiting wasn't an option. Once my employee returned and the engine had cooled down it ran fine again. I put a couple of wooden cloths pins on the steel line to act as heat sinks but I'm not sure it wasn't the rubber hose that vapor locked. This was the first time for vapor locking and I think it was because I had traveled so far uphill and in the 101 degree temperature. It was just like my youth traveling to the eastern sierra's when my Dads car would vapor lock and we would have to sit a couple of hours waiting for the car to cool down while it was over 100 and not a bit of shade along Highway 395, ahh, what fond memories of my father calling the old car every name he could think of without pissing off my mother too much. There isn't much room to reroute the fuel line but I can get rid of the rubber line and go to steel all the way past the exhaust manifold. Besides the cloths pins what other remedies does anyone have for this problem.
Harry
Harry
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Comments
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Harry Hill wrote:Well, it happened today. 101 degrees and a long grade equaled vapor lock on a steep hill. I had to get a tow to finish my trip. I could have waited for the engine compartment to cool down but I was on my way to relieve one of my workers for his lunch break so waiting wasn't an option. Once my employee returned and the engine had cooled down it ran fine again. I put a couple of wooden cloths pins on the steel line to act as heat sinks but I'm not sure it wasn't the rubber hose that vapor locked. This was the first time for vapor locking and I think it was because I had traveled so far uphill and in the 101 degree temperature. It was just like my youth traveling to the eastern sierra's when my Dads car would vapor lock and we would have to sit a couple of hours waiting for the car to cool down while it was over 100 and not a bit of shade along Highway 395, ahh, what fond memories of my father calling the old car every name he could think of without pissing off my mother too much. There isn't much room to reroute the fuel line but I can get rid of the rubber line and go to steel all the way past the exhaust manifold. Besides the cloths pins what other remedies does anyone have for this problem.
Harry
Maybe cover the line that gets hot with some insulating cover ? I think speed shops sell stuff like this. Good luck, Ron0 -
One of the big culprits is the screen in the fuel pump. Make sure it's not partially clogged. If it is, it increases the vacuum on the fuel and boils it, and the pump won't pump vapor.
Carry a bottle of water so you can pour it over the pump if it happens. It will condense the vapor so it will pump again.
Walt Mordenti advocates a (shop vac) hose from the grill area to the pump so cold air blows on the pump.
The clothes pins are an old wives tale. They don't work. You can use some aluminum foil and make a heat shield between the engine and the pump.
If you live in a hot climate like that, I'd put an electric pump under the car in the line with a switch under the dash. That will push cold fuel through the pump when you need to, then switch it off when it cools off.0 -
1. Increase the number of spacers under the carburetor
2. Wrap the gas line (from pump to carb) in a thermal insulator. This is the insulation that has the shiny foil exterior and insulator underneath, and I think you can get it at most car parts places.0 -
If your Fuel hose is suspect I would replace it. If the fuel line goes too close to the motor or manifold I suggest moving slightly and/or wrapping with Termo Tec Insulation or something similar.Probably installing an electric pump near the tank with a switch would help. I assume you have a heat shield under the carb(s).0
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Harry, I don't know if it will work on the AMC Hudsons or not but I ran a rubber line from the Pump to the inner fender panel then through an inline filter then back to the carb. Have not had any problems since.
Bob0 -
I remember my dad cutting up a grapefruit and putting it on the fuel pump as a remedy one trip to the L.A. County Fair when I was a kid.
I was impressed that we got to the fair.0 -
Harry Hill wrote:
This is where Walt's tech tip book will solve your problems. What vapor locks is the fuel pump. Install a fuel return line with an electric pump. If you had just poured a bottle of drinking water over the pump you would have been on your way again Remember, it's the pump. I can drive my 53 in 110 degree weather with air condition up hill to 13,000 feet and no vapor lock. Just turn on the electric pump and it keeps cool gas going through the pump and back to the tank. Do this when you start to climb a hill.Well, it happened today. 101 degrees and a long grade equaled vapor lock on a steep hill. I had to get a tow to finish my trip. I could have waited for the engine compartment to cool down but I was on my way to relieve one of my workers for his lunch break so waiting wasn't an option. Once my employee returned and the engine had cooled down it ran fine again. I put a couple of wooden cloths pins on the steel line to act as heat sinks but I'm not sure it wasn't the rubber hose that vapor locked. This was the first time for vapor locking and I think it was because I had traveled so far uphill and in the 101 degree temperature. It was just like my youth traveling to the eastern sierra's when my Dads car would vapor lock and we would have to sit a couple of hours waiting for the car to cool down while it was over 100 and not a bit of shade along Highway 395, ahh, what fond memories of my father calling the old car every name he could think of without pissing off my mother too much. There isn't much room to reroute the fuel line but I can get rid of the rubber line and go to steel all the way past the exhaust manifold. Besides the cloths pins what other remedies does anyone have for this problem.
Harry0 -
52 kahuna wrote:I remember my dad cutting up a grapefruit and putting it on the fuel pump as a remedy one trip to the L.A. County Fair when I was a kid.
I was impressed that we got to the fair.
Terry, that's the kind of answer I was looking for, something based on science. Now to answer those who don't believe in science. I have an electric pump on the car since the manual pump fell victim to the new gas and I haven't bought a new kit yet. This is the break down of my fuel system ( steel line from the tank through the fender, a short rubber line to an inline filter, another short piece of rubber, then the electric even with the front of the engine for good airflow, then steel line up to the glass bowl filter then into the carbs, both the inline filter and the glass bowl were empty so I'm thinking the either the rubber line vapor locked or the steel where it goes into the rubber unless the glass inline filter boiled and caused the vapor lock. I think the biggest problem was about 6 or 7 miles of continuous uphill with stoplights along the way. I was watching the temp and the car wasn't overheating but it was running warmer than normal. The road temp was probably trememdous and the air temp was over 100. Maybe some kind of scoop under the radiator to direct outside air over the fuel pump would help. I will get some kind of heat shield material but I'm not sure it would help in this case, at least it can't hurt.
Harry0 -
This is where Walt's tech tip book will solve your problems. What vapor locks is the fuel pump. Install a fuel return line with an electric pump. If you had just poured a bottle of drinking water over the pump you would have been on your way again Remember, it's the pump. I can drive my 53 in 110 degree weather with air condition up hill to 13,000 feet and no vapor lock. Just turn on the electric pump and it keeps cool gas going through the pump and back to the tank. Do this when you start to climb a hill.
Walt, pm me with the information I need to order your book. As you can see I already have an electric pump on my car and the vapor lock occurred before the electric pump so I'm not sure your answer is correct either but I do enjoy reading Walts tips in the WTN so I would like to get the book.
I'm thinking if I route the fuel line out of the engine compartment I won't have to pass by the exhaust pipe and that will help keep the fuel cooler. I think if I route the line out through the wheel well into the engine in front of the exhaust system I could help solve this issue.
Harry0 -
Harry,
I thought most electric fuel pumps were pusher pumps that are recommended to be mounted next to the tank. I installed a Mr Gasket pump on my car (12 volt) to supplement my dual action pump when needed and the instructions said that it should be mounted next to the tank. I also have heard that electric pumps are cooled by the fuel running through them more than the airflow across them.
Rich0 -
Harry Hill wrote:
Electric pump alone will not solve vapor lock for it also will get hot. Don't forget the carburetors shut the gas flow till they need more gas and this is where vapor lock starts. You have to keep the electric pump or the mechanical pump cool and my way works great. The story is in volume two (2) page 15 and vapor lock will be a thing of the past if you follow my instructions. For my books, Walt Mordenti 45 Skyview Way San Francisco, CA. 94131-1248This is where Walt's tech tip book will solve your problems. What vapor locks is the fuel pump. Install a fuel return line with an electric pump. If you had just poured a bottle of drinking water over the pump you would have been on your way again Remember, it's the pump. I can drive my 53 in 110 degree weather with air condition up hill to 13,000 feet and no vapor lock. Just turn on the electric pump and it keeps cool gas going through the pump and back to the tank. Do this when you start to climb a hill.
Walt, pm me with the information I need to order your book. As you can see I already have an electric pump on my car and the vapor lock occurred before the electric pump so I'm not sure your answer is correct either but I do enjoy reading Walts tips in the WTN so I would like to get the book.
I'm thinking if I route the fuel line out of the engine compartment I won't have to pass by the exhaust pipe and that will help keep the fuel cooler. I think if I route the line out through the wheel well into the engine in front of the exhaust system I could help solve this issue.
Harry
The 2 volumes are $41.00 and this includes the shipping by priority mail.0 -
Why not just post the answer to the question and allow the fix to occur?0
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WildWasp wrote:Why not just post the answer to the question and allow the fix to occur?
Now that's a very good question. Gotta keep this one rolling. :cool:0 -
Guys, Walts posts tips every issue of WTN that he gives freely to the members. He has also gone to the trouble of publishing all his tips and tech help and would probably like to recoup some of the expense. If he gives all his help away no one will buy his books. It's like being a mechanic and doing all your work for nothing, pretty soon no one pays for your expertise because they can get it for nothing. I will buy Walts book just like I bought the CD's that Alex Burr put together for us. It sure isn't much for all the information you get. Walt, I'll send you a check for the books, thanks alot.
Harry0 -
I guess it is time to add a Pay Pal logo to my website?
Really interesting dichotomy is arising again. What is the purpose of the BBS? I suspect most would say Hudson information exchange. The numbers of folks who come and go and are lurking as guests seem to bear out this theme. I come here to learn from the exchanges that take place and at times because I am able to call on an experience or a tip another Hudsonite has shared I can give that bit back to those who ask.
Making information available to those who are willing to restore their Hudsons, is what my website and I believe Alex web site are all about. All the information you get on Alex' CD is posted on his website. Why, because after many attempts to create interest in all the research and effort he found little interest in buying it as a book or CD. Instead of withdrawing that information and keeping it from others, Alex, decided to put it on a website and still does.
Being a mechanic or a hobbyist has nothing to do with providing information... if the information is being doled out in articles in the WTN what is the loss is providing ONE tip on this BBS?
As one who has had a web presence devoted to Hudsons for over ten years... I find the notion that helping another in deference to selling a BOOK or CD self-serving.
My two cents...0 -
Ken,
Very poignant. Well put. Spot on. And a big THANK YOU to people like you, Alex and others who give of themselves and share.
Dave0 -
Harry, I think the problem is that you are using the electric pump as the only source of fuel pressure. Most electric pumps are designed as a pusher of gas, not as a puller, like the mechanical pumps are. You probably have a low rate of flow of gas, that coupled with the heat gave it time to boil. Replace your old OEM pump and move the electric pump back to just in front of the tank and I think you won't have any more vapor lock.0
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Harry,
Since I am not much of a mechanic, I will offer some advice rather than an opinion on how to fix it.
On the really hot days like we have had recently, I think you should drive the Hash down the hill, not up!
I know, I'll crawl back under my rock and wait until the next cruise night.
Terry0 -
OK, guys here it comes.I am in the midst of experimentation. I have a twin h 53 hornet and live in Tucson. Got fed up with FUEL STARVATION or pre-vapor lock ie.while running on the mech AC pump I will "surge and stammer at times when the temp goes above 88 F. If I drive steady it might be ok to 93 or so. But when stop and go it will starve.Fuel pump shows 5.1psi when normal temps. When the surging occurs, I switch on the electric pump and all is well at least to 102. Last year on a steep 1 mile climb I felt what appeared to be surging even with the electric on. Be advised, my electric pump is installed in a seperate parrellel line NOT IN SERIES, therefore it is independant of a hot mechanical pump( recommended by Walt Brewer of the Cadillac Club for their flatheads).The electric is on the frame rail under the B piller for access. With this set up the elct pump is at 4.5 psi ( I want to keep the pressure a little less for fear of the needle seat being forced open on idle)Last week I installed Walt Mordentis' Fuel feed back system. Walt, the temp was at 95. We took a 32 mile tour on some rolling hills. The first 15 miles I ran on the AC(mech pump),then some moderate accelleration it began to "buck". Switched to the electric( rotary vein style)all was well. I am hesitant on using the elec so I went back to the AC ok until my speed slowed at a stop sign or two. I put the elec on. Now we stopped for some lunch for 30 min. Started the car stalled, restarted ok and off we went with the elec on the rest of the way. A long story longer! When the engine is turned off the fuel has no "post running pressure "the gas runs into the return line leaving an air gap, which requires a longer cranking restart. Later,checked my fuel pump pressures. AC stayed at 5psi, but the elec dropped from 4.5 to 4psi as the the engine idled(or Reved to 1200rpm). That was curious. I was under the impression that with your system I only needed the elec to prime the carbs and could run in any temp with the Mech only. I think I was mistaken.The problem we all have is indeed is that the pumps get hot, Really HOT ! Put a inferred temp senser beam on the pump when this vapor issue occurs. Mine showed 158F. Summer gas will"flash" off at 148. With the combination of fuel ,and the exhaust manifold 5" above the pump and the poor air flow down deep in the block,Well.Insulate the fuel lines? They will eventually get hot and hold the heat. Maybe a heat shield between the manifold and the pump would help. Any one try that? Header wrap also might help. Could soak the cloth in cool water and lay it on the fuel pump to prove a point for about 15 minutes. Walt Mordentis' idea seams good with the elec pump operating. Had to go the confession before the drilling part,Walt. Thank you all for your time Ron.0
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The following is offered by a Hudson owner who was asked this question on another web site:
Answer
Unfortunately this is becomming more and more common, as the new reformulated gasoline has a much higher vapor pressure, and boils much more easily than the gasoline of even a few years ago.
There isn't a lot you can do - but make VERY sure that there are no restrictions in the fuel line between the tank and the fuel pump - no bends, no filter, no crimps in the line, and also make sure that any rubber or other fittings are absolutly air tight. Remember that this area of the fuel system is actually under a vacuum when the pump is running, so a very minor leak, too small to observe fluid leaking when the car isn't running, will still admit some air to the suction side of the pump, bringing about vapor lock at any provocation (like a long hill climb or parking on a hot surface, for instance).
Mount the fuel pump as close to the tank as you can get it, with very short connection lines, and keep all the fuel system as far away from the exhaust system as you can arrange. Add a heat shield if neccesary to keep the lines and the pump cool.
As a last resort, (and totally inauthentic) take a page from modern cars and make a vapor return line from a tee in the carburetor inlet, which returns excess fuel back to the tank - thus keeping more fuel moving through the pump and lines, so the cooler gas in the tank will keep things cool enough to avoid vapor lock. You'll have to experiment with various restrictive orifices in the return line attachment fitting, so that you don't reduce the fuel pressure at the carburetor inlet below about 3 PSI. The fuel pump can provide much more gas than the car will need as long as the fuel is kept cool, so you should be able to find a return line quantity that keeps enough gas circulating that vapor lock is avoided. This design is why modern cars don't have vapor lock problems - the pump can provide about 4 times as much as as will ever be needed, the excess is simply drained back into the tank continuously, thus keeping the lines cool with fresh gas from the tank.
I'm just back from a 1500 mile trip in my Hudson - and experienced that problem for the first time in the 22 years I've owned the car - so I know how frustrating it can be. I plan to try this same fix on my car before the next trip.
Good luck,
Dick0 -
Guys, I have always said how much I appreciate all the advice that is given so freely on this forum. I still bought the CD from Alex though because I appreciate all the work he puts into them. I might complain about how much the cars are selling for right now but that doesn't mean I don't appreciate all the work that goes into them. I can see all the work Bill puts into his cars when I go to his shop. If I buy a car from Bill I will know nothing was done half assed, and he will stand behind everything he sells. I'll pay more for that kind of sale, and I don't mind paying Walt for his book as it will be something I can always reference if I need to, besides, I love owning books, always have. Even though everything in Walts book is available elsewhere there is something about having it in a book.
If you run a recycle line off the electric pump is that a completely separate circuit from the manual pump or is that to supplement the manual pump? I think the WTN has a couple of ads for fuel pump kits with the right material for todays gas. I can put my electric pump back by the tank but the instructions with the pump said to put an inline filter before the pump to protect it from contamination. That will put the filter in a hard place to change but we do what we have to in order to keep these old cars running. Another question, doesn't the tank have to be vented to run the recycle line?
Harry0 -
Harry your hash tank is or was vented. If not that can be your trouble.0
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Billy, it has to be vented or the tank would collapse under drawing fuel from it. I'm just wondering if the vent is one way or does it vent in both directions?
Harry0 -
Harry,
You have to run your 'return' line from the carburetor back to the tank. This removes the excess fuel from that point, as was stated above.0 -
Okay, I understand we are running a return line to the tank. I'm thinking I will have to drop the tank and tap it for a threaded fitting. It appears some people are using the electric to add to the manual pump flow and others are running the electric on a separate fuel circuit that goes around the manual pump. Where do you tee in the supply line for the return line and do you put a pressure valve in the return line so the pressure at the carb stays constant?
Harry0 -
Harry Hill wrote:Billy, it has to be vented or the tank would collapse under drawing fuel from it. I'm just wondering if the vent is one way or does it vent in both directions?
Harry
Vents both ways. I have seen several tanks collapsed from being unvented. Have also seen several that would let the pump starve for fuel and not collapse.0 -
Heart Of Texas wrote: »The following is offered by a Hudson owner who was asked this question on another web site:
"There isn't a lot you can do - but make VERY sure that there are no restrictions in the fuel line between the tank and the fuel pump - no bends, no filter,........ "
I've always heard to put a filter ahead of the electric fuel pump. This has also been included in the instructions for installing a new one. I know this is true to validate the warranty in ones I've used.0 -
A filter is a necessary restriction and in todays market with the degree of carelessness of many employees and corporations you have to have filters in order to protect yourself from contamination introduced in the fuel tanks. Besides, nothing disables a pump quicker than a piece of debris between two surfaces.
Harry0 -
RonS wrote:
My tech tip about vapor lock was in the March-April 2002 issue of the WTN. This proves people do not read the issue or mark it for future use. The electric pump has to be right at the tank outlet with a filter before it. It also has to be in the original gas line, not as a separate line. Then a filter before the pump and a 3 outlet filter between the pump and the carburetor. Then a line back to the tank with instruction on how to connect. The articile has part numbers to use. I started with a 0.060 hole for restriction, too big, then 0.045 and still too big and ended up with a 0.030 hole in the restrictor and no more problems. I did my books because owners were asking me to put all my articile in book form so that they would have quick reference for problems. They have been sent to every country where people have Hudsons. Walt MordentiOK, guys here it comes.I am in the midst of experimentation. I have a twin h 53 hornet and live in Tucson. Got fed up with FUEL STARVATION or pre-vapor lock ie.while running on the mech AC pump I will "surge and stammer at times when the temp goes above 88 F. If I drive steady it might be ok to 93 or so. But when stop and go it will starve.Fuel pump shows 5.1psi when normal temps. When the surging occurs, I switch on the electric pump and all is well at least to 102. Last year on a steep 1 mile climb I felt what appeared to be surging even with the electric on. Be advised, my electric pump is installed in a seperate parrellel line NOT IN SERIES, therefore it is independant of a hot mechanical pump( recommended by Walt Brewer of the Cadillac Club for their flatheads).The electric is on the frame rail under the B piller for access. With this set up the elct pump is at 4.5 psi ( I want to keep the pressure a little less for fear of the needle seat being forced open on idle)Last week I installed Walt Mordentis' Fuel feed back system. Walt, the temp was at 95. We took a 32 mile tour on some rolling hills. The first 15 miles I ran on the AC(mech pump),then some moderate accelleration it began to "buck". Switched to the electric( rotary vein style)all was well. I am hesitant on using the elec so I went back to the AC ok until my speed slowed at a stop sign or two. I put the elec on. Now we stopped for some lunch for 30 min. Started the car stalled, restarted ok and off we went with the elec on the rest of the way. A long story longer! When the engine is turned off the fuel has no "post running pressure "the gas runs into the return line leaving an air gap, which requires a longer cranking restart. Later,checked my fuel pump pressures. AC stayed at 5psi, but the elec dropped from 4.5 to 4psi as the the engine idled(or Reved to 1200rpm). That was curious. I was under the impression that with your system I only needed the elec to prime the carbs and could run in any temp with the Mech only. I think I was mistaken.The problem we all have is indeed is that the pumps get hot, Really HOT ! Put a inferred temp senser beam on the pump when this vapor issue occurs. Mine showed 158F. Summer gas will"flash" off at 148. With the combination of fuel ,and the exhaust manifold 5" above the pump and the poor air flow down deep in the block,Well.Insulate the fuel lines? They will eventually get hot and hold the heat. Maybe a heat shield between the manifold and the pump would help. Any one try that? Header wrap also might help. Could soak the cloth in cool water and lay it on the fuel pump to prove a point for about 15 minutes. Walt Mordentis' idea seams good with the elec pump operating. Had to go the confession before the drilling part,Walt. Thank you all for your time Ron.0 -
Walt, I wasn't getting the WTN in 2002 but it doesn't matter as I like having books. I'm not sure I've ever seen a three outlet filter, did you mean one in and two out? It will be cool now for the next week so I shouldn't run into vapor lock again for awhile. Summer is coming fast though and I want to be prepared. I don't relish sitting in the bicycle lane trying not to get run into again.
Harry0
This discussion has been closed.
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