I had a Honda dropped off this afternoon because it had run out of fuel, the owner refilled and it wouldn't start. I went through the obvious tests, check it has spark put in new plug,pull the air filter and squirt starter fluid in and not a sign of it starting. I then decided to empty the tank ( he assures me it is unleaded 91) and I immediately thought the colour looked wrong. It was a yellowish colour and against the 91 I have here which is an orange colour. Anyway I got it running on my fuel and a new plug ( I believe the diesel has killed the plug) but I am interested to know if there is a simple way to test diesel. When I tip the container to pour the fuel, it has a bluish tinge which is why I think it is diesel. The owner says no way but I have to disagree with him. Any thoughts?
I have had 2 or 3 mowers this last year with what I suspect was diesel and I have no good way of checking either
Once was a loncin chonda motor, the guy was pretty irate and when I sprayed some carby cleaner it blew massive smoke. Drained the tank and I was 90% sure it was diesel. His son later admitted it could quite possibly have been diesel
Another was a sanli from memory
The other was a flat head briggs – the guy brought it down and said he had been trying and trying – the whole deck was smeared in oil out of the muffler – but he assured me he hadn’t tipped it. He realised he bought a jerry can of diesel for his van and had put it in
Only way I can think of is tip a bit on concrete and throw a match at it.
Yes I've also had mowers people filled with Diesel. Yep the lighting of a small amount as Tyler suggested is a good test.
I can tell from the smell , the easiest way to tell is to put a small amount on the ground and try and light the fuel with a match.
As we know. If you toss a lit match into a puddle of diesel fuel, it’ll go out.
You aren't supposed to light fuel at Home for safety reasons but if you're careful to light a very small amount then it should be safe.
Diesel is much less flammable than gasoline. In a car, it takes intense pressure or sustained flame to ignite diesel. On the other hand, if you toss a match into a pool of gasoline, it won’t even touch the surface — it ignites the vapors above the surface. (Please don’t do this at home!)
Hi Norm. Try the stink test. Diesel and petrol have really, really different smells. Diesel is just a light oil- it's got a lot less volatile kaboom! vapors coming off it. Match test a bit of the suspected diesel and if it won't catch fire, that's what it is. If it's really petrol, it will woomph into flame. Other hand, if his "unleaded 91" was bought ten years ago, and has been stored for ten years in a leaky can.....
Whoops. Just saw Tyler and Max had already replied, while I was distracted by Davie Warner's double century stuff before sending you a reply. They are right..
I well I seen Diesel fuel accidentally put in fuel tanks along with Kerosene. I even gotten gasoline that had lots of water. It is frustrating to have this to happen. Here our unleaded gasoline is dyed yellow and the diesel has no dye but is oil color as Kerosene. We can even get bad fuel that will not even light by match or torch.
I once gotten Kerosene as the delivery driver had put it in a diesel tank. My tractor sounded like it was going to blow up. I got over a quart of water in 5 gallon gasoline once. That one cause me headaches as the 300 lb plus tiller died in the middle of a deeply tilled garden patch. One customer filled his zero turn with 5 gallons of diesel by mistake.
So yes things happen by accident and may or may not be the operator/owner causing it. Just chalk it as it happen and move on.
Right I got in an UTV that has a brand new plug in it the is bad. I know the customer is going to say he replaced the plug. Doesn't matter it is bad.
I remember this incident at a Caltex service station in the news in 2015 when 20 cars broke down in succession after filling with contaminated E10 fuel.
This mower is continuing to give trouble. I put another new plug in it New Years Eve because it hadn't stopped again but it was obviously running with the choke on. Choke was sticking on so I added a spring to help it to open. Then I couldn't get it started and the plug was dead. Put in a new plug and all good until today when he rang and said it wouldn't start again. I assume the plug has failed but I have no idea why. This will be the original Iridium that was in it and 2 of mine. Any thoughts?
Could it be an ignition fault? I’m thinking that burning through plugs could indicate either too much voltage or current. I can recall plug faults in a tractor caused by something similar, we were chewing through sets of points and plugs. This was some time ago now so my recollection isn’t clear.
Another option is that there are residues from contamination in the fuel system or combustion chamber causing bridging across the plug. This could “fry” it if there’s enough material.
Either way I’d look at the plug itself with one of those plug diagnostic pictures on the bench in front of me and see whether it sheds any light.
If you’re looking at the second option then it might be necessary to pull the head off and decoke.
If I get a spark problem ,I would try a new NGK or Bosch spark plug and if I still have a problem with the spark I would change the coil.
If you think about it most mower coils can't last for ever with all the heat and vibration that they put up with ,most coils are mounted over the hot cylinder instead of the crankcase end.
As we know.
There are a few things to check if your spark plugs are failing prematurely.
Repeated overheating of the spark plug tip can cause the plug to prematurely fail. Overheating can be caused by many things like pre-ignition and a malfunctioning cooling system. Pre-ignition can lead to heat building up in the combustion chamber causing the spark plugs to fail.
1 take notice if your mower starts to burn oil, as it can be an indicator that your spark plugs may be damaged prematurely
2 check for overheating ,blocked cooling system ,damaged fan or cowl.
3 Pre-ignition ,Black, dry soot on the electrodes and insulator tip indicates a carbon-fouled spark plug. This carbon buildup decreases the lifespan of a spark plug and can lead to hard starts, decreased acceleration, engine misfires ( check fuel mixtures and restricted intake side or restricted exhaust side.
4 The gap between the spark plug’s center and side electrodes needs to be calibrated perfectly to ensure optimal engine performance. Having the right gap ensures that the arcing occurs at the proper voltage to ignite the fuel and generate the combustion that makes the engine run. If the gap isn’t set correctly, extra stress could be placed on the spark plug tip which could cause it to erode and wear out prematurely.
5 A faulty coil will have a plug that is not firing correctly and the plug will become fouled with fuel and oil pretty quickly because it never gets hot enough to burn off these deposits, you can hear sometimes when the plug or coil is faulty because the engine makes popping noises out the exhaust.(like a slight misfire when you start to get a problem) (weak spark)
The fuel mixture can be incorrect if the needle and seat isn't working correctly or the fuel height in the carby is set to high or low.
Every mower I work on the cowl is removed and everything cleaned with compressed air so I know I won't get overheating problems as I assume most of us do this .If you can hear the motor pinging and it's not a weak spark then you would need to clean the carbon out of the motor if there are no other problems causing this.
low compression can cause misfiring as well as a damaged cam shaft .
I'm just about to give up on this one, it came here yesterday with no oil in it I checked the oil 2 days earlier and it was fine, I also had the blade carrier off and no sign of the bottom seal leaking. When the bloke brought it here the pull start wouldn't move and I tipped it sideways and the blade carrier was locked up. My son freed it up and I got it started with no issues. I fitted a new seal but now all I can get it to do is start on choke but it is half hearted and as soon as I move the lever it cuts out. The plugs have all been very black and failed. Put another new plug in it tonight, minimal improvement and I drained the fuel and put some of my fuel in it. I am running out of ideas now
Sounds like there’s a middle step involved that you’ve not been given sight of Norm. Given the initial issue that was perhaps fuel-related maybe the oil was also contaminated?
I forgot to mention that when I checked the oil and I said to him it was empty he then said that must have been where all the oil in the back of his ute must have come from but he continued to mow lawns till it stopped. I can't believe the problems this mower has had in the last few weeks
In that case I’d be interested to see what that seal looked like. A catastrophic seal failure in an older motor is fairly unusual when the seal hasn’t had earlier issues.
The fuel was more than suspect, if contamination somehow was also present in the crankcase then that could result in seal failure. All in all this is pretty unusual.
One interesting thing I’ve recently come across is three non-running full crank Victa mowers being offered for sale by different sellers that seem superficially in good nick but, upon close examination, look to have got very wet. That is the plug has evidence of rust and/or the engine is very very grainy when I attempt to turn it via the blade plate with the plug removed. I suspect they were in sheds that leaked in recent storms or were victims of rising water.
