When a gas golf cart won’t run, there are several steps you can take that can help to determine what’s wrong. In this posting, I’d like to discuss how I go about it,
Let’s assume that the engine “turns over” but won’t start up for some reason. Let’s qualify turns over a little bit first, though. The first thing to be sure of is that the engine is actually turning over, not just the starter generator spinning. There is a definite difference in the sound of the two, so, you should be able to tell by just listening. However, you’d be surprised how many times I had a customer tell me that it was turning over just fine but it actually wasn’t! Of course, you can tell by looking under the seat while trying to start the engine, but that is not recommended, without a few precautions. If you just jump up and pull up the seat and push on the accelerator with one hand while holding the seat up with the other, you’ve got a major problem if the cart “decides” to take off while you are doing it. You need to have the cart in neutral to do it safely. That’s where you need to know “how” to do that. For years, Club Cars have had a nifty little “cam” that could be turned on the back of the F/R switch, that allows you to start the cart in neutral in what is called the “maintenance mode”. The problem is that when you put the shift lever in neutral without moving the cam to this position, the F/R microswitches that provide activation of the cart’s ignition system and the energizing of the solenoid (main contactor) won’t activate, so pushing the accelerator down in neutral won’t spin the engine over. On other models, like the Yamaha G16, the cart will still start with the F/R switch in neutral. On those, you just need to be very careful that the cart “stays” in neutral while you are working on it. There is no “detent” in the neutral position, and it is spring loaded to keep the shifter in both forward and reverse, so it is easy to accidently bump the shifter while working on it, and if it starts, off it goes. You need to study the cart that you are working on to be sure of how that works. An even safer bet is to get the back wheels up off the ground, just in case something goes wrong.
So, if the cart does indeed, turn over, the next step is to determine if the problem is related to the ignition system or the fuel system. Remember, if there is a proper mixture of fuel and air in the combustion chamber and there is a proper spark from the ignition, it almost HAS to run. Let me qualify that just a little. We also need Compression in the combustion chamber and the timing of the ignition needs to be correct, but with compression, timing, fuel and spark, things should go BOOM!
If you have a compression issue, it generally shows up a little at a time over a long period of time, not just all of a sudden. Timing is not generally “adjustable” on a golf cart. The mechanical timing is set either by gears (Yamaha and Club Car) or with a belt (EZ Go), so unless something pretty unusual has happened, that wouldn’t be the place to start troubleshooting. The electrical timing is set by an ignitor that gets its information about when to fire from the position of the flywheel and an ignition coil, so, there are lots of possibilities for problems there, so we’ll visit those components in general more specifically in just a bit.
Most of us, who are trying find a problem the issue with one of these carts, begin with an “in-line” ignition tester. The kind you can buy at most auto parts stores. To use one, you just put it in line between the spark plug and the wire that normally attaches to the spark plug. It’s a great little tool (and very inexpensive also) because it allows you to “see” if the ignition is “firing”. The tool contains a light source (probably neon) that blinks a very noticeable flash when the ignition fires. There is, however, one thing I’d like to mention about using one. I have had, on a few occasions, a situation where I could see a flash with each firing of the ignition, but the cart still wouldn’t start AND the problem still ended up being an ignition problem. There is such a thing as “ignition” and then there is ”IGNITION”. After using the tool for a while, you finally get a pretty good idea of just how “bright” the tool should flash to indicate that the spark is “hot” enough. But let’s say that it looks OK, so for now, we’ll go on to the fuel possibility.
Probably the easiest way to see if you are getting fuel to the carburetor is to simply pull the line from the fuel pump to the carburetor off, at the carburetor end and spin the engine over and see if it has fuel coming out. If it does, you can forget about the fuel pump, fuel filters, etc. So, if you have fuel to the carburetor from the pump but the engine still won’t start, the next thing I would do is to try to see if there actually is fuel in the carburetor. A simple way to verify that is to open up the “drain” port on the bowl of the carburetor. This assumes that it is accessible, but they usually are, with a little looking and feeling around. If you get it open, and no fuel comes out, chances are good that the needle and seat valve in the carburetor is stuck. Time to remove the carburetor and see what is going on in there. In the old days, the needle and seat would probably have been replaceable, but not now. You can try cleaning and polishing it, but you are probably better off to replace the carburetor and be done with it.
If there IS fuel in the carburetor, but the engine won’t start, another test that I would run, is to spin the engine over for a while and then pull the spark plug out and look at it closely. If it is wet with fuel, then there is an even better chance that the ignition isn’t actually “hot” enough. If the spark plug is “dry as a bone”, then off comes the carburetor. Perhaps the main jet is clogged with tarnish (particularly if the cart has been sitting for a while). Another thing to look for is the “vent” line that comes out of the carburetor. There is a port coming off of the top of the carburetor (somewhere) that is supposed to have a line running from it down to the bottom of the engine compartment. Lots of times, on older carts, the line is missing (just hasn’t been put back on after a carburetor cleaning or something), but you will find the port up there somewhere. If it gets plugged up, air can’t get out of the carburetor, so fuel can’t get in. When that happens, the symptom is usually that the engine will start but only run for a short while (until it runs out of what fuel has accumulated in the carburetor). When the engine is shut off, enough fuel will “seep” into the carburetor with the pressure released, to partially fill the carburetor. But just enough fuel to go for a short while. When the needle and seat opens to refill the carburetor, the fuel can’t get in, because it can’t push the air out.
If there wasn’t any fuel coming to the carburetor from the fuel pump, then we need to work back in that direction. In order to troubleshoot in that area, we need to understand how the fuel pump works. You will notice that it has three lines attached to it. It will be easy to identify the ones coming from the fuel tank and going off to the carburetor, but often times, the problem can be with what’s happening with the third line. The fuel pump works by receiving “pulses” of pressure (both positive and negative) from the crankcase of the engine. When the piston is headed “down” the cylinder toward the crankcase, it puts positive pressure on the crankcase volume. When the piston is moving “up” the cylinder, it “sucks” negative pressure from the crankcase. The third line to the fuel pump is attached to a port directly off the crankcase, so it reflects both positive and negative “pulses” with each stroke of the piston. These pulses to the fuel pump cause a diaphragm within it to “pull” fuel from the fuel tank, and “push” it toward the carburetor as “permitted”. By permitted, I mean that when the needle and seat in the carburetor open up, the fuel will flow due to the pulse pressure. However, when the needle and seat close, the fuel can’t flow anymore, so the activity of the pulses is for “not”. There is only a small amount of pressure put on the diaphragm, so it just stops moving as the flow is discontinued. The amount of pressure that the fuel is pushed with toward the carburetor is only around a pound and a half (PSI), so nothing is damaged when the needle and seat closes and the flow is shut off.
The correct way to test the operation of the fuel delivery function is with an actual pressure tester. If you connect it directly to the pulse line going to the engine block, as you spin the engine over, you should see it jump wildly from positive to negative with each reversal of travel of the piston. If you put it directly to the input side of the fuel pump (after removing the line from the fuel tank), you would see a suction (negative) pressure build up slowly. If you were to put it on the output side of the fuel pump (after removing the line that goes over to the carburetor) you would see it slowly build up to about the pound and a half PSI that I mentioned.
Without the tester, about the best you can do is threefold:
On the pulse input line from the crankcase, put your finger over the end of the line and see if you can feel the “sucking and blowing” as the engine spins over.
On the input side of the fuel pump, use your finger to see if the fuel pump is “sucking”. It won’t be a great big suction (that is why using the tester is better), but you should be able to feel a slight negative pressure.
On the output side of the fuel pump, use you finger to see if you can feel a slight “push” of pressure toward the carburetor.
Things that can go wrong with the system include dirty or clogged fuel filters and cracked or collapsed fuel lines. Another common problem is that the line that goes to the crankcase (pulse line) gets crushed or cracked. If there aren’t real good pulses to the fuel pump, then things can either work marginally or not work at all.
There are several ways to go about checking for fuel issues, but most of us now put “clear” fuel filters in the fuel line so that we can look at them and get an idea of what is happening. I ALWAYS put two fuel filters in the line. One between the fuel tank and the fuel pump, and another between the fuel pump and the carburetor. There should be some fuel in both when everything is working correctly. They won’t be FULL, but there should at least be some trace of fuel in them. When the needle and seat valve opens in the carburetor to let fuel in, that’s when you should see fuel flowing through both filters. Once it closes, the flow stops, but the filters should at least be “wet”. If either filter is totally dry, we’ve got fuel system issues. So, by looking at the clear fuel filters, you should be able to verify if the fuel pump is working or not, without even taking anything apart.
Some common problems that stop the flow of fuel to the carburetor include:
Obviously, the fuel pump can go bad.
Any of the fuel lines can develop a leak.
The tube that provides the pulses to the fuel pump from the crankcase is a VERY common source of problems. They can dry out and develop cracks so that the pulses to the fuel pump are weak or nonexistent. On some models, the line is routed under the air intake system, and can even collapse from something laying on them. Because they are right next to the engine, they are subject to much more heat than the other two lines. Be sure to look it over, blow through it, etc.
If there is debris in the gas tank, it can get sucked into the end of the fuel pick-up line and stop everything. Get your flashlight out and look down in the tank to inspect it (I wouldn’t use a match).
A fuel filter can get clogged, but it is rare, because they have such a large surface area inside that it takes a lot of debris to clog one.
So, let’s assume that you haven’t any fuel problems, but there is no spark (ignition). As I mentioned before, the timing of the spark is set by a mechanical means (belt or gear), so that USUALLY isn’t where you would start troubleshooting. The electrical timing can involve one of several systems. In a book that I wrote, called Gas Golf Cart Repair 101 (and a half), I spent over two chapters trying to describe how they all work, so I won’t try to repeat all of that work here, but we’ll just discuss, in general terms what they look like.
Club Cars use an actual magneto system with an ignition coil sitting next to the flywheel of the engine, sensing when a very strong magnet comes around and goes by it. The ignition coil, however, has an electronic ignitor built into it that regulates the spark advance. At least the newer ones do. The older ones had a separate ignitor mounted on the front of the engine (in a real handy place to get to if you like standing on your head and working with a mirror). There is also a device to sense the RPM of the engine and shut things down when the RPM reaches an unsafe level. It can also shut things down by becoming defective, so one of the tests is to disconnect it and see if your problem goes away. Once, again the book has detailed descriptions of these things and schematics of the wiring and their components.
E-Z-GO uses an ignition coil that sits up near the top of the engine. It is “fired” by an ignitor that is in its own package. The ignitor is told where the flywheel is by a thing called a “pulser”. The pulser sits right next to the flywheel and detects when a “slot” that is cut in the edge of the flywheel comes around. The spark advance is provided by the ignitor.
Yamaha uses a magneto system similar to the Club Car with the ignitor built into the ignition coil sitting next to the flywheel (which also contains a magnet).
Anyway, I hope something in this post might give you just a little picture of what is going on and what you might check for, Ron.
For information about books written by Ron Staley about both electric and gas driven golf carts and their repair, visit the following links.
Electric Golf Cart Repair, both as an eBook and in Hardcopy:
Book: Ronald L Staley: 9780578560557: Amazon.com: Books
Gas Golf Cart Repair, both as an eBook and in Hardcopy:Gas Golf Cart Repair Book: Ron Staley: 9798987911303: Amazon.com: Books