lawn tractor won't start--good battery, new solenoid, jumps starts immediately

I have an MTD 1993 16 hp lawn tractor.

When I turn the key it goes tick tick tick tick tick very quickly--it's not the "click" sound. I've heard the "click" sound before, and this isn't it. The engine doesn't turn over at all. But if I jump start it with a car battery, it starts right up without any hesitation at all.

The battery is fully charged according to the needle on the charger (I don't have an instrument to measure volts). I charged it for two days.
I just bought a new solenoid and installed it. Didn't solve the problem. Sounds exactly the same.
There is no corrosion, loose wires, etc. -- if there were, it wouldn't start right up when jump started, right? Same with spark plugs. If that was the problem, why would it start right up from a jump start?

If the starter motor were bad, why would it start right up with a jump start?

I'm out of ideas. I should add that although I can repair things, what would take an ordinary person two minutes will take me an hour. I have 0 mechanical ability, and have virtually no idea what various parts are called or what they do. I know the basics: tractor, wheel, gas tank....

I would first remove battery & take to a local auto parts store & have them load test battery, this should be of no charge to you. If you have to purchase a new battery make sure it has enough CCA'S, cold cranking amps, per your manual.This will let you know if your battery is good or bad.

https://www.tractorsupply.com/tsc/product/traveller-u1-250-rider-mower-battery?cm_vc=-10005

this is just an example

usually that rapid ticking is when my battery is dead, or very low.

The clicking is because the solenoid is not seeing better than 11V.
There is a simple method of elimination to work out where to voltage drop is happening.
IF you have a pair of jumpers.

1) run a jump from the battery - to a good ground near the starter (the oil drain bolt is good )
Engine cranks fine = bad ground from battery

2) run a jumper from the battery + to the + on the starter ( expect a BIG spark when doing this )
Engine cranks fine = battery is good + starter is good

3) move this jumper to the starter side of the solenoid
Starter cranks = cable is good

4) move the jumper to the battery side of solenoid
starter cranks when you turn the key = bad + connection to the battery + solenoid is good

5) if the solenoid has a single lower wire , run a jumper from the battery - to the body of the solenoid.
Engine cranks with the key = brad ground contact on the solenoid

6) run a thin jumper from the battery cable on the solenoid to the trigger terminal at the bottom
engine cranks = bad cranking circuit.

Sounds like a bad connection. Likely a bad ground.

mechanic mark said:

I would first remove battery & take to a local auto parts store & have them load test battery, this should be of no charge to you. If you have to purchase a new battery make sure it has enough CCA'S, cold cranking amps, per your manual.This will let you know if your battery is good or bad.

https://www.tractorsupply.com/tsc/product/traveller-u1-250-rider-mower-battery?cm_vc=-10005

this is just an example

Click to expand...

You were right. My charger showed that it was fully charged, and it was. I took it to an auto parts store, and they had a volt meter under the counter. They tested the battery, and it was fully charged. But the "cold cranking amps" only = 21, which apparently isn't enough to actually start the mower (I've tried to research this online, but I cant' find anything to really explain it.) Anyway, we got a new battery, installed it, and it started right up.

So I learned two things:
1) The battery can be fully charged and still not work correctly.
2) The fast "tick tick tick tick" sound = battery problem.

Scrubcadet10 said:

usually that rapid ticking is when my battery is dead, or very low.

Click to expand...

You were right. My charger showed that it was fully charged, and it was. I took it to an auto parts store, and they had a volt meter under the counter. They tested the battery, and it was fully charged. But the "cold cranking amps" only = 21, which apparently isn't enough to actually start the mower (I've tried to research this online, but I cant' find anything to really explain it.) Anyway, we got a new battery, installed it, and it started right up.

So I learned two things:
1) The battery can be fully charged and still not work correctly.
2) The fast "tick tick tick tick" sound = battery problem.

A battery is a chemical reaction chamber where a chemical reaction that can be reversed results in current ( AMPS ) passing down the cables.
How much current can pass down the cables is proportional the the VOLUME of the chemicals ( called paste ) that is available to react.
The Voltage is a measurement of how far the reverse reaction ( called charging ) has gone,
IF there was just 1 molecule of active paste available to react & provide electricity the Volt meter will read 12.5 VOLTS or better.
However if you try to use that 1 molecules worth of electricity , it won't even cause a dull red glow in a globe.

Every time you reverse the reaction by charging the battery, a little bit of the paste is consumed so the volume of chemicals available gets less & less.
That is where your battery was at which is why the first test is to try and drive the starter directly from the battery using jumper leads.

CCA ( Cold Cranking Amps ) is a measurement of how fast the reaction can happen and for a mower you need between 200 & 300 ( or better )
AH is Amp hours which tells you how much chemical is in there to produce power, the higher the better and the more expensive.

Mower batteries don't last nearly as long as car batteries in terms of number of start cycles. I tried to take care of them by keeping them charged during winter months, but at the end, it doesn't matter much. They only last about 5-6 years at about 30-40 starts per season. I wonder if motorcycle batteries would do better in mowers. So far, I have been buying $19.99 Walmart batteries.

The best battery is a pressure valve regulated , adsorbent Glass Mat , spiral cell .
But that will cost you over $ 100 a price most flat out refuse to pay.

We used them in the transport fleet & in the hire cars but I had to lie, cheat & steal to get them into the trucks at the lst salaried job because senior managment was just plain too cheap, which puts them on par with 99% of the public.

Most can not understand the difference between the price as seen on the bottom of the sales docket and the actual cost.
My service van had a $ 400 battery in it, it has been in there for 10 years & will probably run another 10.
The landlords electric fences are running on some 15 year old batteries I took out of the hire cars when that business folded.