Causes and fixes for warm start issues

hello folks and welcome to the channel or welcome back and in this video we're going to be talking about hot start problems more specifically on older vehicles with carburetors and electronic or non-electronic ignitions you most likely have come across this problem you start up your car when it's cold then it cranks up beautifully you drive away with it you have your right and then all in a sudden you have to fill up the car or you want to get some coffee you do this kind of pit stop you turn off the engine you get your coffee or you fill up the tank then you get back in the car happily with your coffee cup in your hand you know you try to start the car and guess what the bloody thing doesn't start so now you're stuck you have to wait a while you zip your coffee until it's empty and then you try again and all of a sudden the car is starting again and you drive happily away a common problem caused by heat and this video is trying to address all the possible causes for that kind of an issue and i had exactly that problem and i've been working on it for two days to find the actual cost and that's why i decided to make this video [Music] and now we do have a problem and the only thing you can do right now is enjoy your coffee until the engine is cold and then start again of course we're not going to sit there and zip our coffee we need to find the cause of the problem but one thing we can say already is that the cause is heat it could have an effect on the ignition and it could have an effect on the fuel system so let's start with the fuel system if the fuel system is the cause of the problem then there's only two reasons either the engine is flooded or the engine is suffering from starvation of fuel now i will be looking at a carburettor type because that's what most of our older vehicles have and the fuel that we used to have in the old days was quite different than the fuel we have today today we have a lot of additives so that has changed the characteristics of the fuel now the fuel is going to evaporate faster than what it did before and that's why we may have a problem with what we call vapor lock a very well known term amongst many people and being used many times for problems and often it really isn't vapor lock but what is vapor lock now vapor lock is nothing more than the creation of gas bubbles emitted from the gas itself inside the fuel lines and that is typically caused by heat now the old fuels didn't have this issue but modern fuels as i said before are having additives to it and it makes it more um lighter it the boiling point is lower so we're going to have more gases being created at lower temperatures with modern fuels so you'll see that you're going to get air bubbles in the fuel lines here and these air bubbles are going to start blocking the fuel supply to the carburetor now what can you do about this to prevent this well there's a couple of things you can do first of all do not use metal fuel lines that's the first thing i would say and try to use rubber types that will avoid a lot of heat transfer compared to steel types or copper types the second thing is that you might want to go for a electrical fuel pump located near to the gas tank and not a mechanical one located on the engine block because on the engine that fuel pump will collect heat and if you're turning off the engine the heat will still rise for a while and then it will drop down so these are the main things you can prevent vapor lock so run all your fuel lines away from heat sources try to do it with a rubber hose specifically designed for fuel lines and also try to have a return to the fuel tank so you keep circling that fuel from the fuel tank all the way to the carburetor and back now most cars have a single line system but there you can actually fix issues quite easily with installing an electrical pump near to the gas tank and even with a single line that will work properly so i'm going to give you a little demonstration of what vapor lock is and i have a tube here with fuel inside and i'm going to heat it up a little bit and you will see that all little bubbles that will start to appear vapor of the fuel but first of all let's check the temperature that we have for the moment 20 degrees sandy gray so let's heat it up and see what happens i don't want to make it cook of course and i will check the temperature once we are at the right temperature but it takes a bit of time because this is a fairly large tube so if you look closely you can actually see the bubbles being generated and this is exactly what happens in your fuel system when you have vapor lock i'm going to take the heat on this just to show you and it's around 45 degrees centigrade now you know that an engine typically runs around 70. so you can see this is happening very early and very quickly you have seen that these gas bubbles are generated very quickly even on low temperatures it started at around 45 to 50 but around 75 degrees centigrade it was quite violently so if you have hoses that are bent in one or another way this gas will travel up the bend because gas always gets to the highest point and it's going to form right here on the top lock a vapor lock as we call it so i call it gas gas bubbles but actually there are vapor bubbles and they're going to be sitting right here on the top and fuel can no longer pass so your engine will be suffering from fuel starvation however fuel starvation is not the only problem with heat the engine can also suffer from fuel flooding so once you stop the engine it's going to have a certain temperature right a running temperature let's say around 75 to 80 degrees centigrade of course when you stop the engine that cooling circuitry will stop right you won't have no more cooling the ventilator stops and the water pump has stopped so heat will build up in the engine and that heat will transfer through the intake manifold into the carburetor and that's what we call heat percolation now when heat percolation happens then your carburetor is going to get real hot and when the carburetor gets hot fuel in the fuel chamber will expand and that could cause flooding through the emulsion tubes or to the jets it can cause all kinds of issues so that's another thing we need to prevent now of course the first thing you need to do is to make sure that your carburetor has the proper float level so adjust your float level to where it be because the float level determines the height of the fuel in the emulsion tube and in the flow chamber so if the fluid level is too high you may have exactly the same problem and it might be that due to the heat the fuel is expanding and then it's going to leak out through the jets so make sure that the float level is right and the fuel pressure is as critical as actually your float level make sure that you have applied the right fuel pressure to your carburetor so setting the right fuel pressure for your carburetor is very important so i always recommend to install a fuel pressure regulator to combined with a filter and adjust to the right pressure for your specific carburetor i'm using about three to four and a half psi on my edelbrock but of course that will be different for different carburetors and you need to find out because that pressure will also affect the float level in your carburetor fuel chamber if heat percolation is a problem on the vehicle then you can install a spacer which is going to insulate the intake manifold from the carburetor the existing wood but they're also special spaces are provided by your carburetor producer i'm using a spacer from edelbrock which is about the centimeter thick which is going to insulate the heat from my intake manifold to my carburetor and that is not an aluminum one it is a special material that insulates heat very well anyway but before you do so make sure that your fuel lines are sorted out make sure that your float level is good make sure that you have the right pressure on your carburetor and if you can fit an electrical fuel pump away from the engine so on this engine we have fitted the performer intake manifold and it sits straight onto the block of the engine so that's going to get a lot of heat from the engine and the carburetor what i'm having installed is an edelbrock cmf 500 but it doesn't really matter and what you can see is that i have like a centimeter thick spacer here this black part that is a special spacer i bought from edelbrock to insulate the heat from the intake manifold percolating into the carburetor and that makes a difference so let's do some measurements so i'm going to measure the temperature on the intake manifold and what i measure is around 50 degrees centigrade if i measure it on the carburetor on the flow chamber i have around 36 degrees centigrade so we looked at the fuel system and we tried to fix all the issues on the fuel system and i've applied all those measures on this vehicle and guess what my next stop at the gas station same problem so now it was time to investigate on the ignition system now what can be wrong on the ignition system well typically spark plugs could be polluted and they may create an arc between the electrode and actually the insulation because of the coating of carbon on it but that is normally not the problem um of course you have to fit the right spark plugs in it so for the right temperature the hot or the cold ones depending on the performance on your engine i might do a separate video one day on spark plugs themselves but consider that the sparklings are okay consider that all your high tension leads are okay there could still be a problem with your distributor with your electronic components of the ignition system and your ignition coil these are the three possible areas where you could have a problem so imagine that this is your ignition going to fit it into the engine and of course you're going to have your high tension lead coming off and a lot of other wires going to your distributor in the plus 12 volts so what you need to do really is to heat that up while the engine is cold the engine is running and it's still cold warm up that ignition coil you know and then see what the engine does once it's warmed up to about 75 degrees or 80 degrees centigrade turn off the engine and try to start it if it doesn't start you have a bad ignition coil another quick check you can do in the ignition call is to disconnect all the cables and then measure with an ohmmeter set to a very low scale and i've set it to 200 ohms then put the two pins together of your own meter see what the losses in your leads and i have like 0.3 and then actually measure the impedance across the plus and the minus of the ignition coil now that typically should be more than 1.2 and here i have actually 2.6 so actually i have 2.3 considering the loss of my own cables so this is good uh this is another thing you can do and you can heat it up meanwhile and see if this is gonna change if you have a spare ignition girl it doesn't hurt to change it out and i changed mine out very quickly and make sure that you have the right ignition coil for your engine because some require a ballast resistant in front and others don't so don't forget that part because that can cause also issues now uh the next step is of course the distributor and we're going to be looking at my specific distributor but it's applicable to all distributors because they all have common parts so let's have a look on that distributor so now we can look on the distributor what the possible causes could be i've taken one of the shelf here because it's easier to show it to you than in car now this happens to be a lucas 35 dlm-8 but it doesn't really matter um because all distributors are more or less the same and i'm now referring to more older cars i'm not talking about brand new cars that's quite different and it doesn't really matter if it's a four or nine or a six cylinder so the first thing is we're going to take off the cap and you can do this with clips or with screws whatever it is so let's take the cap off make sure that you have a proper cab that all the contacts inside are clean this one is not this is an old cap but make sure that is really good and that the carbon tip there is still intact and spring loaded very important and then check that the rotor is good this rotor is an old one not very good as you can see i've seen issues with distributors that get hot where the rotor is actually starting to leak because of carbon buildup between the core here and actually the metal part in the back and then the circ the high tension voltage that is supposed to go to the spark plug this way over this copper uh conductor here is actually not going that way it actually is jumping over to that part inside here and then to the ground and you get very poor spark so it's always good to make sure that your distributor is in a good condition and then replace it you know it's like a two euro two dollar piece so it's cheap don't take risks all right let's put that aside and now we are back down to the actual distributor itself if you have a breaker point based distributor check the condensator on the side that might be shorted but this is an electronic version with an electronic pickup now inside you have a moving part and then you have a coil that picks up the signal and on the side we have an amplifier and we'll get in more detail into this in a few minutes now the amplifier itself is on this one mounted onto the distributor in other applications you will find the amplifier away from the distributor now this specific distributor the 35 dlm 8 from lucas and silver similar distributors have an issue when engine is hot heat comes through the body of the distributor and the amplifier which is sitting right here which is actually amplifying the pulses getting from the induction system and then with those leads allows current to flow through the coil or not is getting very hot and this is built with solid state devices and i will open it for you so you can see it when this is getting hot it tends to break down or it changes the parameters on how it behaves and that's why you get bad starting conditions in my specific case on the car i was working on i have changed the amplifier here from a aftermarket part to the original lucas part and believe me it made dna different and it fixed my problem so you could have a problem with your pickup points which is very unlikely or you could have a problem with your amplifier and the best way to check this is if you have an oscilloscope or you go and buy immediately a replacement amplifier but buy an original one don't buy an aftermarket one because they are crap believe me i've tried three of them they were all three crap and this is a crappy one and the reason that this car had a problem with hot starting was a faulty ignition amplifier it would work fine when it was cold although on higher refs you could hear misfiring every so often but when the engine was hot the components inside were really hot as well of that ignition amplifier and it changed completely the behavior it actually moved the timing completely off and that's why i couldn't get it started so i replaced this aftermarket part with a original genuine part from lucas and my problem was solved now i know there are solutions to extend this amplifier on this specific distributor towards your bulkhead with a wire or a cable you can do that if you want to i probably might do that over time i'll see how this goes but now if you're more interested in how this 35 dlm8 distributor works or in general on how electronic distributors work stay tuned because i'm going to take it to my little workshop where we're going to hook it up to the scope and a signal generator and we're going to have a look on how this is working if you're not interested in this i hope you enjoyed this video and you can skip out in fact you can always skip out whenever you want but if you do enjoy it and you want to watch further well bear with me so let's go i have the distributor on the workbench and what you can see inside is a pickup coil which is magnetic underneath here you have a magnetic strip and then the middle part is the part that will rotate and then on the side you have the amplifier when the engine is running you'll see that the middle part will be rotating and you see all these wings here and i have eight wings on this because i have an eight cylinder if you have a four cylinder you have four wings and each of those wings represents a cylinder and a pulse so while this is rotating it's going to pass this pickup coil here which is magnetized there's a magnet underneath here you can probably see that my screwdriver is hanging on it and then it will change the magnetic field because it's passing and because of that it's going to rate a very faint pulse and that pulse is fed over those two wires to your amplifier now that pulse is not strong enough to generate power through the ignition coil let me take this apart so we can have a bit of a better look so the parts on the distributor very simple we've got the distributor itself with all the bob weights inside underneath here the vacuum advance system and then this toot wheel here where we find the wings one for each cylinder that's going to rotate while the engine is running we have the pickup system which is a pickup coil this is not your ignition coil that's the one which is magnetized as you can see oops and this connects with two leads towards the amplifier and this is the amplifier and it will connect to those two pins now the signal coming out of this pickup point is very very weak so it needs to be modified amplified and then it can drive a switch or a transistor to drive the current through the ignition coil and the ignition coil is driven through those two outer pins in fact it's a negative side going to the ignition coil the other pin is actually a plus 12 volt spin for feeding the amplifier module now the amplifier module is fitted onto the housing through this bracket here and you see the white stuff if you're ever going to install a module like this let me remove my screwdriver you're going to need something like this this is heatsink paste so this is a special compound that allows heat to be transferred from this amplifier onto the body of the actual distributor for cooling purposes you actually see that on the back here if you look at this you see these little vents here this will aid to the cooling um but in my case it didn't help too much as you've seen so now let's put this together a little bit and we're going to do a few tests with the oscilloscope then we're going to hook it up and warm it up again and i'll use an ignition coil to show you what the effect is when it warms up so i've hooked up the oscilloscope to the distributor and more specifically to the output of the pickup point if i'm now going to rotate the distributor we should see pulses coming up for every wing on the distributor so let me try to run this of course i'm spinning it by hand so it's not very steady so you're not going to see evenly distributed pulses all right so i captured that so these are the pulses that we now picked up these are the pulses that the picker point picked up from the distributor and each of these pulses or peaks reflects the wing passing by that coil inside the distributor and this will drive the ignition coil but of course this is not long enough in time it is not powerful enough in time so this shape has to be reworked the bottom part has to be cut off so we want to end up on the square wave and that's the whole purpose of the amplifier that we have on the distributor so now let's hook up the amplifier and see what happens i've rigged up the distributor as it would be in the car with the power supply in the back a high tension coil and a spark plug and if i'm now going to rotate the distributor the pulses will be picked up right there on the pickup point they will be amplified by the amplifier current will be driven through the coil and the secondary winding will pick that up of the high high tension coil and it will actually spark the spark plug so let's see so i'm going to turn it and hopefully you can see it and i'm going to give you a bit of a close-up on the spark plug itself and i can see the sparks going back and forth i reconnected the scope so you can actually see the pulses that are coming out of the ignition amplifier they will be quite different than what we saw at the input so let me try to capture this for you the trace on the scope shows the output of the ignition amplifier and whenever it's low we have current flowing through the ignition coil that's what we call actually the while angle now that there is a variation that's me actually rotating the distributor not equally because i do it by hand and when the pulse is high then we have the plus 12 volts and then there's no current flowing through the ignition coil um so that's the moment in time we actually are getting the sparks so when the peak is up so always a spark is generated when the current is dropped on the coil so this is going to be the last test we're going to do on this amplifier module i have it rigged all back up i have the module i took away the distributor so i'm feeding in a signal which is normally would be the same as what comes out of the pickup points into the amplifier module and then i'm having a spark plug on the other side so the amplifier module is driving the high tension coil and we have a spark plug also there so which is the sparks are going right now and here i can actually see on the scope um what the pulse is on the actual high tension coil on the low side so um now i'm running on a very low frequency but if i would trouble up the engine which which means increasing the frequency then you should see that picking up very quickly seeing so then these puzzles are getting much closer to each other so so now you can see the sparks on the spark plug and if i reduce the frequency or the rpms on the engine you'll see these sparks are going to get less in period right so it's going to get lower and lower and this is how the ignition system works so now we could actually increase the temperature on the module and see what happens with it the sparks stopped and that's just because i have removed initially the output of the pickup coil and i if i put it back up like i would start engine now from warm because now this module is really warm it doesn't work anymore i don't get sparks and that's exactly the problem we are having see now it's coming a little bit by little bit but it's not working so i'm going to measure the temperature on the actual module itself and it's not all that hot to be very honest it runs around 40 degrees centigrade and it has already crept out on me so so folks been here in the end of this video and all i can say is if you're going to replace the ignition amplifier on your lucas distributor or any other distributor because it's acting up when it's getting warm or at high rpms then um don't replace it with a aftermarket part and let me turn this off because it's a bit of noise and i may also turn off the engine because these aftermarket parts are not that good they suffer from erratic behavior at high temperatures or higher temperatures and in high rpms so try to go with the genuine original part there's a huge price difference between them the lucas ones is quite expensive it's about five times or six times the cost of an aftermarket one but we know why so um i might still want to show you the inside of it so you can have a peek what it is there's not much to be seen inside it's just some electronic circuitry because this module is doing more than just amplifying the pulse it is also adjusting the dwell angle depending on the rpms the engine is making so if you're running on high rpms the dual angle is staying the same normally but the time it takes to pass these amount of degrees is less so the current through the ignition coil is less and in that case um you don't charge up the coil enough with the electromagnetic field so the spark is going to be weak so what these modules do as well is they actually reduce the dwell angle so they make the dwell dwell angle a bit longer so that you have more time to charge up the ignition coil at high rpms anyway we can talk a lot about this but i don't think that's the purpose so i hope you enjoyed this video a bit as much as i did and i'll see you in my next one which is going to be a little more hands-on mechanical thank you for viewing

Channel: D3Sshooter

Views: 8,133

Rating: 4.9661732 out of 5

Keywords: edelbrock, vapour, lock, heat, percolation, carburettors, fuel pressure, regulator, fuel line, lucas, v8, rover, landrover, my car does not start, when warm, pick-up, coil, ignition, amplifier, heat gasket, how to fix it, spark, distributor, after market, 35dlm8, problems, measuring, details, testing at home

Id: tu6F_8jYlFk

Length: 26min 35sec (1595 seconds)

Published: Sat Sep 05 2020