bluefoxamazone Posted October 21, 2014 Report Share Posted October 21, 2014 Has anybody installed a non return or one way valve into the fuel line? Does this help to make the engine start easier after been sitting for a couple of days? What experiences with installing an extra electric fuel pump that only runs when the startermotor is running? thanks Quote Link to comment Share on other sites More sharing options...
Merle Coggins Posted October 21, 2014 Report Share Posted October 21, 2014 A check valve wouldn't help your starting issue. The problem is that the gas will evaporate out of your carborator when it sits. I have an electric fuel pump in the line near my tank that I can switch on to assist a quicker fill of the carb for starting after sitting for a while. Merle 1 Quote Link to comment Share on other sites More sharing options...
DonaldSmith Posted October 21, 2014 Report Share Posted October 21, 2014 I don't think you would crank the starter long enough to fill the carburetor bowl if you had an electric fuel pump that only works while the starter is cranking. I have a McMaster-Carr double pole switch for my electric fuel pump. In one direction, I hold the switch on, to fill the bowl. The pump sounds different when the bowl is full. In the other direction, the switch provides constant power to the pump, in the event that the mechanical pump fails. The fuel pump switch is the middle one, on the auxiliary panel I made (parking brake light, instrument panel lights, fuel pump, and auxiliary fan. The fan switch is double throw, up for automatic, center off, and bottom for constant on.) 3 Quote Link to comment Share on other sites More sharing options...
suntennis Posted October 21, 2014 Report Share Posted October 21, 2014 Carter sells a 6 volt fuel pump which they say should not have gas pulled thru it from another pump down line. With this in mind, they sell a check valve that can be used in a line that would go around the electric pump line and join the main line going to the mechanical fuel pump. The check valve prevents gas pumped from the electric pump to recirculate instead of being pushed thru the mechanical pump. With this setup there would be one line from the gas tank that would divide into two lines. One of the lines would go to the electric pump and one would go to the check valve. These two lines would then connect to the main line going to the mechanical pump. Quote Link to comment Share on other sites More sharing options...
Plymouthy Adams Posted October 21, 2014 Report Share Posted October 21, 2014 actually..you already have a one way valve in your carb..needle and seat...but as the carb is not a sealed system, evaporation is the killer bee here and will have to contend with that and also newer fuels are such that evaporate and at my dismay..seem to do that in a sealed container...try it some time.. Quote Link to comment Share on other sites More sharing options...
Young Ed Posted October 21, 2014 Report Share Posted October 21, 2014 actually..you already have a one way valve in your carb..needle and seat...but as the carb is not a sealed system, evaporation is the killer bee here and will have to contend with that and also newer fuels are such that evaporate and at my dismay..seem to do that in a sealed container...try it some time.. The fuel pump has one too. I agree its the evaporation that can be a killer. I personally do not have issues with either my pickup or coupe. Even after 5 months of storage they start. Quote Link to comment Share on other sites More sharing options...
dlrides Posted October 21, 2014 Report Share Posted October 21, 2014 With proper float level and a heat shield, starting issues usually disappear. No need to complicate a simple system. IMHO 2 Quote Link to comment Share on other sites More sharing options...
bluefoxamazone Posted October 22, 2014 Author Report Share Posted October 22, 2014 With proper float level and a heat shield, starting issues usually disappear. No need to complicate a simple system. IMHO You wouldn't have a drawing or a picture of such a heat shield on the desk? This sounds like an excellent solution to heep the heat away from the carb. thanks, Quote Link to comment Share on other sites More sharing options...
pflaming Posted October 22, 2014 Report Share Posted October 22, 2014 When does the fuel evaporate? When the engine is turned off and still warm, or just over time. Is evaporation a larger problem in cold climates or hot climates? Quote Link to comment Share on other sites More sharing options...
Don Coatney Posted October 22, 2014 Report Share Posted October 22, 2014 I thought you were you a high school teacher? This is from the chem4kids web site. Sometimes a liquid can be sitting in one place (maybe a puddle) and its molecules will become a gas. That's the process called evaporation. It can happen when liquids are cold or when they are warm. It happens more often with warmer liquids. You probably remember that when matter has a higher temperature, the molecules have a higher energy. When the energy in specific molecules reaches a certain level, they can have a phase change. Evaporation is all about the energy in individual molecules, not about the average energy of a system. The average energy can be low and the evaporation still continues.You might be wondering how that can happen when the temperature is low. It turns out that all liquids can evaporate at room temperature and normal air pressure. Evaporation happens when atoms or molecules escape from the liquid and turn into a vapor. Not all of the molecules in a liquid have the same energy. When you have a puddle of water (H2O) on a windy day, the wind can cause an increased rate of evaporation even when it is cold out. Energy TransferThe energy you can measure with a thermometer is really the average energy of all the molecules in the system. There are always a few molecules with a lot of energy and some with barely any energy at all. There is a variety, because the molecules in a liquid can move around. The molecules can bump into each other, and when they hit... Blam! A little bit of energy moves from one molecule to another. Since that energy is transferred, one molecule will have a little bit more and the other will have a little bit less. With trillions of molecules bouncing around, sometimes individual molecules gain enough energy to break free. They build up enough power to become a gas once they reach a specific energy level. In a word, when the molecule leaves, it has evaporated. The rate of evaporation can also increase with a decrease in the gas pressure around a liquid. Molecules like to move from areas of higher pressure to lower pressure. The molecules are basically sucked into the surrounding area to even out the pressure. Once the vapor pressure of the system reaches a specific level, the rate of evaporation will slow down. 1 Quote Link to comment Share on other sites More sharing options...
pflaming Posted October 22, 2014 Report Share Posted October 22, 2014 I'll ask my question again, "When does the fuel evaporate? When the engine is turned off and still warm, or just over time. Is evaporation a larger problem in cold climates or hot climates?" I understand evaporation and that environment plays a direct role in that process. The environment of the carb is a combination of environments: the engine compartment with a changing environment, the carb with a 'semi' sealed bowl, the storage place of the vehicle i.e., the climate,time the vehicle is idle, to name a few. SO MY QUESTION remains, do we know which conditions increase the when the evaporation rate of the fuel from the carb ? Quote Link to comment Share on other sites More sharing options...
_shel_ny Posted October 22, 2014 Report Share Posted October 22, 2014 You wouldn't have a drawing or a picture of such a heat shield on the desk? This sounds like an excellent solution to heep the heat away from the carb. thanks, http://p15-d24.com/files/file/42-fuel-pump-heat-shield-template/ Quote Link to comment Share on other sites More sharing options...
Jeff Balazs Posted October 22, 2014 Report Share Posted October 22, 2014 Paul; I think it stands to reason that most of the rapid "evaporation" that occurs at the carb is actually caused by heat induced percolation due to the proximity of the exhaust manifold. This why lowering the fuel level in the float bowl can help reduce gas fumes. It gives the gasoline a little more area to expand into before it leaks out of the float chamber. All the other evaporation that occurs pales in comparison to the effect that heat from the exhaust manifold has. IMO the standard manifold arrangement on these engines leave a lot to be desired. Jeff Quote Link to comment Share on other sites More sharing options...
Dave72dt Posted October 22, 2014 Report Share Posted October 22, 2014 I'll ask my question again, "When does the fuel evaporate? When the engine is turned off and still warm, or just over time. Is evaporation a larger problem in cold climates or hot climates?" I understand evaporation and that environment plays a direct role in that process. The environment of the carb is a combination of environments: the engine compartment with a changing environment, the carb with a 'semi' sealed bowl, the storage place of the vehicle i.e., the climate,time the vehicle is idle, to name a few. SO MY QUESTION remains, do we know which conditions increase the when the evaporation rate of the fuel from the carb ? The warmer it is the faster it'll evaporate. Shortly after shutting an engine off, it'll reach it's peak temp and peak evap rate, as evidenced by some with the percolation problem. As the engine cools off, the rate of evap slows down. I have no idea at what temp it does not have some evaporation, maybe a MSDS sheet would say. Stands to reason cooler climates would have a lower rate of evap than a hot climate. Reducing engine heat to ambient air temp would be faster in a cool climate than hot. Since carbs are vented to atmosphere, evap is going to happen, at least in the carb. Quote Link to comment Share on other sites More sharing options...
bluefoxamazone Posted April 7, 2015 Author Report Share Posted April 7, 2015 still haven't figured out what is going on... I did this test: I let the motor run for 1 minute, so carb is full, no radiating manifold heat. Carb bowl is cold. Let the car sit for 2wks. Tried to start. Took aprox 1 minute before the engine runs fine. It must be that the gasoline is slowly flowing back to the tank I guess. Trying to start the car the next day. It took no more than 10 seconds before running. This week I am going to cut the fuel line and install a one way valve close to the tank. If that doesn't work I am buying an in line fuel pump and wire it so, that it only runs when the starter is engaged. The seller claims that the mechanical pump is able to pull the gas through the electric in-line pump. We'll see what happens... Quote Link to comment Share on other sites More sharing options...
Labrauer Posted April 7, 2015 Report Share Posted April 7, 2015 I have an electric fuel pump and a one way valve on my 48 coupe and I have no problem with the mechanical pump pulling fuel through the electric one in fact I don't have the electric one powered anymore. I will reconnect it later on when I bypass the mechanical one but leave in the car for extra protection. I have heard that the diagram in the mechanical could fail and gas getting into the crank case but with the easier starting of the engine do to the gas being there when I need it I will take the chance. On the other hand when I installed the one way valve it still didn't help with the gas situation in the carburetor. Some how I still lost gas I guess from evaporation from the carb or the fuel lines. mysteries always happen around here. 1 Quote Link to comment Share on other sites More sharing options...
Merle Coggins Posted April 8, 2015 Report Share Posted April 8, 2015 In 2 weeks time the gas will evaporate out of the carburetor since it is vented and gas tends to evaporate. An electric pump will help prime it quicker, if it is strong enough to push through the mechanical pump. I have one installed like that in my truck but I find that it can't always pump through both check valves in the mechanical pump. But if I crank it briefly, then wait a few seconds, (with the electric pump on) that will shorten the cranking time to start the truck after extended periods of rest. Merle Quote Link to comment Share on other sites More sharing options...
TodFitch Posted April 8, 2015 Report Share Posted April 8, 2015 still haven't figured out what is going on... I did this test: I let the motor run for 1 minute, so carb is full, no radiating manifold heat. Carb bowl is cold. Let the car sit for 2wks. Tried to start. Took aprox 1 minute before the engine runs fine. It must be that the gasoline is slowly flowing back to the tank I guess. . . For that the gas would have to go up hill from the level in the carburetor float bowl to get to the inlet for the tube from the fuel pump. Isn't going to happen. In 2 weeks time the gas will evaporate out of the carburetor since it is vented and gas tends to evaporate. An electric pump will help prime it quicker, if it is strong enough to push through the mechanical pump. I have one installed like that in my truck but I find that it can't always pump through both check valves in the mechanical pump. But if I crank it briefly, then wait a few seconds, (with the electric pump on) that will shorten the cranking time to start the truck after extended periods of rest. Merle +1 Quote Link to comment Share on other sites More sharing options...
1941Rick Posted April 8, 2015 Report Share Posted April 8, 2015 Its a nature of the beast...the carb is just a glorified juice can. the fuel leaks and evaporates...you have to learn to live with it....not a big issue.....remember this is very old technology...... Quote Link to comment Share on other sites More sharing options...
bluefoxamazone Posted April 9, 2015 Author Report Share Posted April 9, 2015 quick update... I had the car in the garage for two full days without starting. This evening it started from the first turn... it gives me hope... 1 Quote Link to comment Share on other sites More sharing options...
meadowbrook Posted April 10, 2015 Report Share Posted April 10, 2015 My d34 also needs a long crank to start after sitting a while. But I am thinking this is a good thing, assuming the battery is fully charged. I noticed that in these situations, the long crank builds up my oil pressure prior to the engine firing up. Isn't that better than subjecting all those moving parts to combustion pressures with no oil pressure? Quote Link to comment Share on other sites More sharing options...
bluefoxamazone Posted December 20, 2015 Author Report Share Posted December 20, 2015 just coming back to the subject... I am seriouly considdering to finally installing an extra fuel pump. A rebuild carb, check valve, heat shields, adjust choke sytem, did not help to shorten the cranking time after the engine has not run for a few days so far. What would be the best inline pump to buy. I want an electic pump that allows the mechanical pump to draw gasoline through the electrical one. I find numerous types and prices on the net but I will follow the experiences of the specialists among us. I think I will use it only for priming. thanks for the advice!! regards from Belgium where it should be freezing right now.... Franky Quote Link to comment Share on other sites More sharing options...
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