How to Diagnose a Classic Car not Starting

[Music] hi I thought I'd share my experience of a problem I had with my classic car recently it's a triumph stag but could apply to any old-fashioned type car design with a single coil ignition system basically the car was running very roughly kept stalling idle I would only really go properly when you put your foot down a lot I thought initially it was the carburetor it was flooding and it turned out to be the coil the ignition coil that was gradually on its way out and the spark was getting weaker and weaker so it might be useful to share this experience because if you such a problem you might want to know how to diagnose it and I'll show you some of the steps that you go through to do so so this guy broken down on the side of the road and there's normally two things it's gonna be see the fuelling or the ignition those are the common things so the easiest one to eliminate is the fueling so you could go to the carburetor try and identify whether you're getting fuel into the engine so on this motor is actually converted to be a holley carburetor as we see here and a Holley when you move the throttle cable it actually pumps some fuel into the throttle body and I see if we see that it's squares fuel so there's obviously fuel inside the float chamber the other way of checking it and check whether your needle valves are sticking is again on this holley undo this lock nut try and take a note of where the adjusting screw is so you don't have to adjust the float level undo the nuts the whole needle valve assembly will then lift out you can see where they're sticking on art's see where the fuel is inside the float chamber as one for both sides this is the main one for normal running the secondary side is just for higher revs higher performance side that kicks in later if you've got different carburetors like on the original strong Burks or you might have an su perhaps on the old engine then again look for the float chamber what you could do is under the fuel line be careful because this is going to be probably pressurized so put some rags around it take it off carefully see if fuel is squirting out obviously don't doing smoking at the same time button on this one I put a in-line fuel pressure gauge in line with the fuel supply since it's got reasonable pressure so fueling didn't seem to be the problem so the next thing is to identify what is the ignition so I put them down on the side of the road fortunately had my trusty old kneel and strobe lights which is good for telling you all sorts of things that are wrong to the car so what had to do is disconnect this aftermarket mission coil which is Asli starting to short out internally was getting weaker and weaker temporarily at the moment I've got a more modern style coil just slapped into position just to get me home and with it working correctly you'll see with a strobe light my name's connect jeans the spark plug the other one going into the ignition lead that was going to that spark plug and what you should see on the strobe lights is a nice regular beat and a reasonably bright light coming out now at this point I'd slowed down the video because otherwise you get some strange stroboscopic effect between the frame rate of the video and the flashing of the strobe so this is about four to five times slower then you'll actually see terms of the flashing rate but here you can see with good coil it's flash it's flashing strongly and next we see what it looks like with the bad coil you can see even though it's flashing slowly again then it's a very dim light very weak flashing light was a good indicator that spark is very weak and basically the spark only made it as far as the distributor and by the time they'd been being distributed out across the air gap in the distributor there was virtually no spark going into the engine hence why I wouldn't start yeah the potential probably you might have a course is a problem inside the distributor itself so most of these old cars the distributor cap comes off with a couple of these spring clips it's useful to have a screwdriver to try some off my hand so here's the distributor cap off sometimes you can get tracking ID carbon tracks that conducts the spark away from this contact services this is where the spark comes in right on air rotates distributes the spark around these contact points that go to each of the spark plugs make sure this little graphite water which is on a spring is sticking out sufficiently to contact onto the walk around these can wear out sometimes now Marley's off clean all the surface off especially of any carbon or any white deposits on these contacts give it a spray with oil sometimes moisture in here that can affect how the spark travels around it's not unknown for these rotor arms to malfunction first to have a short in them did happen to a friend of mine months look for any obvious cracks or trekking on them okay and give it a bit of a cleanup if you've got a distributor with point still in it this has been converted to electronic magnetic pickup system we have you got points you'll have a condenser which the capacitor cost some points again those can malfunction short out you can check that again by looking at whether a spark is generated using your strobe lights now also with a multimeter connected to the low voltage point of the coil to see if it goes up and down as the engine turns over and the points opening close now it's also tell you whether you've got bond with points or months and the other thing you can do to finally confirm that it is the coil rather than the low tension side that's causing the problem is to build a multimeter to measure the voltage on the supply side this is coming from the ignition side so this should be around 12 volts and this side goes through the points so what you could do is just connect this down to a chassis point down to ground take these otherwise off it first actually the points serve the job of doing just that connecting you down to ground which buzz currents through the coil if you take the connectors off but a wire off and on down to ground that will then generate a spark and it strobe lights on the output of the coil can still see a very weak spark and that confirms it's definitely the caller was gone which was the case for this car if you see a strong spark then suspect your points or your condenser or your electronic ignition but for me the next job is to change the coil now I managed to find quite a nice one on eBay so this one is a spark right aftermarket coil the company's been going around for years and years back to about the 80s or 70s or so I believe I've heard of them probably older only 15 UK pounds this one comes with a ballast resistor you need to use or not so the idea of a ballast resistor is that you supply the coil fire the resistor during normal operation so from this comes from the ignition supply initial switch when it's starting you want to give the spark an extra boost because your battery voltage is a little bit lower and so a lot of old car systems design for ballast systems will supply 12 volts to this side of the resistor just when the engine is turning over and gives a boost to the spark not always necessary I could run it all the time through the ballast resistor probably could run it all the time direct to the court depending on the specification of your points and the rest of the ignition system and here we have the new coil fully installed I haven't got around to connecting up the connection from the starter motor to the outside of the ballast resistor yet but it seems to start perfectly well without it get round to do that one of these days so let's just see how one starts [Music] lovely running engine so obviously in this case it was the ignition coil was the problem which is why I broke down hopefully this video helped you diagnose possible breakdown possible problem with your L classic car one other problem I did have in the past as related to the wiring getting old and corroded because this is a 40 year old car and things like the fuse box news box is located over there underneath that plastic cover but also anyway you've got a wiring junction the copper itself can corrode and the wire then gets more resistive and the problem I had was that the wiring to the fuel pump which is in the butcher it's actually located underneath this carpet carpeted box cover and the wiring to that to say go to is this different and what happened was the pump which is a sort of reciprocating design pumps in and outs when the spring-loaded returned it would go out for wouldn't come back so it would pump and then stop which means if you'll see all filled pressure stops and the car installed strangely by turning off the ignition and turn it on again they would then restart so that was the symptom of the fuel pump sticking and what I did is just to run another wire from the fuse box back to the fuel pump and then never had that problem again it's a diagnose that particular problem it took quite a long time one had to do in the end was to install this fuel pressure gauge and get these on eBay and likes this is the obviously the petrol feed into the carburetor and I actually have a little webcam here wired into the car radio screen so I could actually see the fuel pressure and when it stalled I could see the fuel pressure had dropped off which means the engine was to be a start to fuel and that was a way of diagnosing what the problem was so hopefully these little tips will help somebody to diagnose their problems and well good luck wheels and thanks for watching bye [Music] you [Music]

Channel: comeinhandynow

Views: 30,978

Keywords: Triumph stag, Car wont start, Car starting, Car broke down, How to fix my car, Classic car breakdown, My car wont start, Diagnosing car, Why wont my car start, Car running rough, Car stalls, Weak ignition coil, Testing ignition coil

Id: iF0EKD5pky8

Length: 11min 27sec (687 seconds)

Published: Sat Mar 02 2019