If you were troubleshooting the starting issue or extremely poor engine performance and came to the conclusion that your fuel system should be checked, this article is for you.
Here, I’ll walk you through general troubleshooting of the whole fuel supply system as well as extensive troubleshooting of every component in it.
Park your tractor safely on an even surface, turn it off, take the keys out of the ignition and let it cool for a while.
Make sure that you’re following all the precautionary, safety measures when working with flammable materials, electricity, and machinery. If that’s the case, let’s proceed further.
Ensure that other systems are functioning properly.
Also, find out if you are caught up with basic maintenance like changing your air filter and spark plugs in time, adjusting the spark plugs (or how deep they sit), checking if the oil level is between two dots, checking if your valves have been adjusted in time and whether or not the oil is good according to the user manual (or YouTube videos on the same subject).
How to test the whole fuel system?
A quick way to test your fuel system is to spray some starting fluid in your air filter port (when the filter is off); if it helps your fuel system is inoperable.
Another way is to disconnect and ground your spark plug leads, close the choke, crank the engine a couple of times, then remove a spark plug and check for fuel at its tip. If there is fuel, your whole fuel system is fine; otherwise, your fuel system needs to be checked more thoroughly. You should dry your spark plugs afterwards with some cloth or paper (and it’s not a bad idea to perform this act before the test as well).
What your fuel system is comprised of?
The job of the fuel system is to ensure a steady and consistent supply of fuel to the combustion chamber.
The fuel system consists of a gas tank along with a tank cap, inlet fuel line, fuel filter, vacuum fuel pump, outlet fuel line, carburetor and some gaskets along with a few check valves.
Checking the gas
First, check if there is any gas in your tank by looking at the fuel gauge or shaking your lawn tractor “side to side” and listening for the gasoline splashing inside.
Now, if the gas was sitting in the tank for over one month, and you didn’t use any stabilizer fuel additives, you might want to change it by pumping the old one out with a fuel siphon pump or leaking it out through an inlet fuel line, previously disconnecting it from the inlet port of the vacuum fuel pump, and putting fresh gas in. A good way to test the fuel is to smell it through the gas cap; if it has a sweet vinegar odor to it, the fuel definitely went bad.
The fuel starts breaking down after 30 days and loses its effectiveness. Moreover, modern gasoline contains ethanol in it, which draws condensate to it that makes it go bad even faster. The worst thing is, this condensate contributes to a fuel system clogging up (all of it, including the carburetor and the fuel pump). Ethanol also dries up your rubber/plastic fuel lines which contributes to cracks and breakages in them, it also can contribute to oxidative/chemical damage to your carburetor and damage little solenoids, rubber plugs, and gaskets.
Inlet fuel line, the gas tank cap, and the fuel filter
To test your inlet fuel line for clogging or cracks, your fuel filter, and your fuel cap (for ventilation); you’ll need to gently unplug the fuel line from the inlet port of your vacuum fuel pump, by unclamping the clamp on the inlet pump port with pliers, previously preparing a container for testing the fuel flow and squeezing the fuel line with pliers for preventing an unwanted fuel leakage.
Then, place the disconnected end of the inlet fuel line so that flaw from it would go into your test container and unsqueeze the fuel line to test the flow. If there’s a strong enough influx of fuel and there are no fuel leakages through the fuel line, your inlet part of the fuel system is good. If there were some leaks through the line, you would have to change your fuel line.
If there is no fuel flaw or if it is very weak, you might want to unscrew your fuel cap and try again. If there is a flaw after unscrewing, you need to change your fuel cap.
If that didn’t help, you might want to change your fuel filter. If the problem persists, you’ll need to completely take your inlet fuel line off your tractor and unclog it by spraying compressed air into it and then spraying some degreaser.
The Vacuum fuel pump and outlet fuel line
First, you need to unplug your spark plug and ground it where the fuel won’t reach it.
To test your vacuum fuel pump and outlet fuel line, you need to unplug the outlet fuel line from your carburetor, squeeze it to prevent unwanted leakage, and direct it into the prepared container to test the fuel flaw (which could be very strong).
Then, crank the starter to see if the fuel is running adequately strong. If it isn’t, you have a problem with either your outlet fuel line or your vacuum pump.
You may want to inspect your vacuum pump for cracks or physical damage to determine if it’s bad.
You can also remove your outlet fuel line, flush it with pressured air, then a degreaser and give it one more chance.
If there’s no flaw, your vacuum fuel pump is dead or clogged very badly
If the rest of your fuel system was fine, yet you’re still not getting fuel into the engine, you should test your carburetor.
In order for you to check your carburetor, you will have to completely uninstall it and take it apart. If it’s clogged up, a thorough cleanup is due. You will need different brushes, a good carburetor cleaner, and also not to forget all those jets (including the needle) and the float bowl.
However, if it’s not just clogged up with fuel residue or dirt and has some serious oxidative/chemical damage from the ethanol in the fuel (especially if it was sitting for a couple of months), it’s better to replace it with a brand new one altogether; because even the ultrasound clean-up may not fix the issue as the physical size of these intricate passages and jets won’t be proper ever again, which may render it completely inoperable.
Another part where the problem may lie is the diaphragm, in which case you need to change it.
You should also check the choke linkage, it should be stranded for the choke to work. And check the electrical carburetor shutoff valve for 12 V with a voltmeter when the key is in the ignition.
First of all avoid using fuel with more than 10% ethanol in it as it draws moisture to the fuel system, which speeds up rusting of its metal parts. It also affects chemically the metals and especially plastic and rubber components.
Most of the fuel system problems lie in improper storage and lacking maintenance.
So to prevent these problems in the future, change your fuel filter in time and prepare the machine for storage properly.
To prepare your fuel system for storage, you should start using stabilized fuel as you approach storage time. In fact, you should always use stabilizing additives to protect your fuel system components.
However, if you still have some amount of not-stabilized fuel sitting in the tank, you should either run it out or pump it out with the siphon pump. Then fully fill the tank with fresh fuel previously mixed with the stabilizer additive and let the mower run for a couple of minutes (before storage).Good luck!