Please recommend your favorite diagnostic tools, gauges and sensors that you use!

Hi,

I'm interested in purchasing a few diagnostic tools so that I can more accurately find the source of lawnmower problems. Is there such a thing as an air/fuel ratio sensor for a lawnmower? If so, can anyone recommend one? What's the best compression gauge? Any opinions?

It would be really cool if you could hook up a single gauge that would give you a readout of any problems.

Thank you!
Scott

Are you serious ?
Air/ fuel meter ? carbs are all fixed jets so a waste of money
Compression gauge ? most have a decompressor so again a waste of money

The best tools ever invented for diagnosing mowers are
1) eyes
2) ears
3) nose
4) seat of your pants
5) brains

If you need a tool to plug in to tell you what is wrong then you need to find another job.
Compression testers are good for small hand helds and you need one with multiple heads that emulate the spark plug cause an extra 5cc capacity on a 20 cc engine will give you a garbage reading.
You need a leak down tester for mowers not a compression tester.

Diagnostic kit for lawnmowers
1) spark tester x 2
2) can of carb cleaner
3) sheet of writing paper.


If you want toys then get a very small bore-a-scope , with a panoramic head small enough to go in the dip stick hole.
Saes a lot of time pulling down engines that are beyond economic repair.

Time is money and this is the 21st century. misdiagnosis cost money!
Thank you for your reply sir! I'll look into your recommendations!

I have no idea of your level of technical skills but from the text it would appear to be very little or you have invented some sort equipment that you think turns people who do not know which end of a screwdriver to hold into an ace mechanic.

The majority of mower problems I repair have nothing to do with the engine, other than the fact that the real problem causes the engine to stop.
Excessive valve lash is the biggest motor problem and no diagnostic tool will pick that up, but you can hear it when the engine is cranking, you can hear it with the response to throttle.
Same story for blown head gaskets, you can hear them the second the engine starts or does not start as the case may be, you can smell it & you can feel it.
Same story for a bent/ broken/ fallen off pushrod
Mowers never run rich unless an owner has done damage to the jets, or even left one out all together and lean will cause the engine to surge.And again you can see hear & smell it.
So an air /fuel meter is going to tell you it is lean, guess what ? surging tells you the same thing and you confirm it by application of your pinkey.
But the meter will not tell you if it is a blockage in the fuel supply system or an air leak post the emulsion tube.


I could go on for hours but I won't.
What you seem to have problems coming to terms with is while this is the 21st century, lawnmower engines have not changed very much since the 19th century when the first governed engine was built.
In time the EPA regulation will force them all to become fuel injected and some MOWERS ( not engines ) are preparing for this by running all the wiring through the hour meter and eventually they will have a diagnosis plug attached to it but that is a fair way off, and just like the auto industry each & every company will use a different plug & different coding systems.

The only tool that actually does save time is the bore scope and again that is mostly on hand helds as it is quicker to shove it down the plug hole than to remove the heat shields & pull the muffler.
It is also handy to check valve seats.
But mostly it gets used to show customer why I told them their engine was trashed without laying a spanner on it.

Compression testers are less than useless for single cylinder engines, you need a leak down tester for them to CONFIRM your diagnosis .
ON hand helds again not much use as very few give true readings on low volume engines and in reality what is needed is a series of tests over time to monitor wear, not a single one of test which may CONFIRM that there is insufficient compression to support combustion, but that requires you to know what the limit for that engine is . There is a massive variation from 50 psi up to 90 psi.

Pressure & vaccuum testers are required for hand helds, no magic diagnostic tool is going to replace them and they can take a very long time to hook up.


So FWIW my diagnostic tools consist of exactly what I first mentioned. a spark tester ( $ 20 ) a can of starting fluid ( $ 10 ) & a multi meter, the sheet of paper was an addition I got from this very forum.

Most diagnose everything type tools take longer to set up & calibrate than it takes a reasonable mechanic to do the repair.
Almost every garage had a Vane Engine Analyser sitting on the wall. $ 20,000 worth or PR bull dust and most of them stay on the wall looking impressive if the real mechanics have the time to dust them.

SSA how long have you been working on small engines ??? I got a lot of repairs under my belt and I only use the basic... mininum of diagnostic tools....

I do have a comp tester but like Bert said, unless you know the highs and lows of engines because of the ACR on the cam you will think all newer mowers are bad.........

A good digital mutli meter......
2 good Oregon neon spark testers.. Bert and I love those..... Model 42-031
Comp tester if you want to get one don't go El Cheapo.........
Tachometer a good one not the 10.00 hour tach meter.......
A charcoal lighter fluid bottle.....
A sheet of B&S paper LOL.....

I'll think of a few more later...... I have a mower to finish repairing ~!~!

Plus Tard Mon Ami ~!~!

Thank you! Good info! I'm working my way into the repair business in PA. I'm too old to learn things thru experience. I'll be dead by then. So I'm looking for ways to shorten the learning curve.

I appreciate everyone's responses!

As stated, all your sences are your number one diagnostic tools and the more you use them the better they get. So you are upgrading your tools are no extra cost to you. Because I do a lot of work on tractors and electrical diagnosis is a big part of the job, my test lights are out a couple of times every week. I have two, one with will read voltages and a second one which can be hooked to the units battery and I can also use it as a power supply. I would only recommend them if you have a good electrical knowledge and are going to work on units where electrical problems are likely to come up. Why, because they can be very helpful, but my two cost over $200, big investment and for most techs not worth it.

FWIW I bought the repair run near 6 years ago, and as I have been playing with old Pommie motorcycles for 50 years, thought it would be a doddle.
It wasn't. Very few repairs are engine based cause they are nearly all fixed jetting and governed.
Most of the repairs were wiring based.
If you are setting up a new shop, the bare minimum will suffice.
A good Vacuum / Pressure pump
A leak down tester ( can be made very cheap )
At least 2 if not more spark testers ( search this siite, Boo found some really cheap )
A test lamp with a coloured globe ( you can't see a white one in daylight )
A couple of multimeters . I find the needle ones easier to use than the digital ones and avoid the Auto range types they are a regular PIA

If you are new to engines then a ColorTune ( Gunsons make them ) but in reality you only tune carbs older hand helds.

Buy a couple of John Deer Technical manuals, the 100 series and a rear engine one .
The diagnosis proceedures are written very clearly , and better still explaned , read them cover to cover and in particular the electrical section.

Make a big pot of coffee and hook into you tube
in particular subscribe to
Donnyboy73 :- totally dead pan, sound advice lists all the tools & parts used and is correct.
Taryl Fixes All :-you can skip the first 5 minutes of all of Taryls videos if the school boy humour is not to your taste again everything he dose is done properly and in the proper light.
Joe Pace - 2 stroke diagnositcs ( from the Husqvarna tech school )

Remember it is a mower, not the space shuttle, not a NAS Car top fueler.
Watch them all , will take a few weeks.
keep a note pad with you and make notes about tools, & equipment.

Mowers are small and space it tight so 1/4" & 3/8" sockets are the go and in particular deep sockets.
And thin wrenches, spend a little extra and get some good ones, I use Stahlwhile because they are the thinnest I can find, thin width and thin around the rings, makes a big difference.
Avoid any "mechanics tool kit" most are trash & overpriced. Old tools bought from car boot/ trash & treasure sales will be better and even more so if they are not chrome plated

The one tool that is essential is a good impact wrench and the bigger the better because those blade bolts self tighten and even with the big 3/4 drive. I still have to cut 3 or 4 nuts/bolts off each season.
Of all the tools this will be the most expensive and the one you can not scrimp on.
I started with the set you get with a cheap compressor and out grew them in no time flat, bought a second one then finally bit the bullet and bough the highest torque one I could find $ 1400 and worth every cent.\
Then had to buy a bigger compressor to power it so start out with 300 cu,ft/min or better and get a good air chisel to go with it.

Finally go to http://outdoorpowerinfo.com/ and go through all of the carb rebuilds. Bookmark it. The belt replacement section is also handy.

And just so you know I spend twice the time chasing parts than I do actually fixing mowers.
Get a tax number and open accounts with Oregon , Prime Line, Rotary & Stens, between them you should be able to get about 90% of everything you will need and 99% of what you get from them will be good enough for you to warranty your repairs and at an after market wholesale price so you can add a reasonable mark up and still come in under Amazon prices.

On the top navigation bar you will see a grey icon labled "new posts".
Every morning click on it and quickly skim through the posts.
That will give you a good idea of what to expect coming through the door.

Buy as many old non running mowers that you can afford the go through them & fix them up.
I keep a few and give them to customers when it gets busy and I am behind, quite a few of them get sold to the customers for a back up.
The time you spend fixing them is "free" and you can do things like plug up the main jet, then remove it all together , loosen the bolts to make a lean run, open out the valve lash , to teach yourself what they look & sound like, even pour some water in the plug hole & crank the engine to blow a head gasket from a hydraulic lock.

SSA wow you are getting some awesome info on here....... When a few of us on here started in the late 70's and early 80's we didn't have this type of info readily at our fingertips....

We learned thru Mentors and refresher courses through the brand name schools and we had to pay for them too.... Now everything is right there in front of a screen in our face..........

Steve's Small engine Saloon is another great channel to watch..... He is straight forward like Dony Boy is.........

A leak down tester from HF is a good investment
A vacuum and pressure tester is a must have for weed eaters and chainsaws..... I can send you a link if you want it.......

The link for the spark tester is here and you will not find a cheaper price anywhere..
www.walmart.com/ip/Oregon-42-031-Sp...6645&wl11=online&wl12=983947256&wl13=&veh=sem

Just carb cleaning doesn't cut the mustard for chainsaws........ If you have to do a top end overhaul on a saw or weed whacker then you have to find out what happened to the unit.... Yes you can put a top end on it and a month later it comes backs to you, then YOU have to warranty it and you just lost money..


Let us know Mon Ami ~!~!

This is fantastic info gentlemen! I now have several recommendations to get me headed in the right direction.

Thank you!
Scott