Mountfield R28M ride on Mower not starting (Again!!)

WIAWSNB

That's helpful.

Yes, the pinion - it's a PINION! - would have been stuck up from your previous attempt.

There are three possible causes:

1) Flat battery. You have charged the battery, but have no way to test it, so it's quite possible that it is faulty - ie, won't 'hold' a charge, regardless of how much charging you give it.

2) The starter motor/solenoid is faulty.

3) The wiring in between the two is faulty.

The blue arrows point to the nuts which presumbly hold the starter motor in position.

The green arrow is where the heavy-duty cable supplies the starter motor. If you trace this, I suspect it'll go directly to the battery? If it does, then it's LIVE, and if you touch it to any part of the mower body (the 'earth'), you will get sparks aplenty, and possibly worse. So, if you do ANYTHING to that wire, disconnect the battery FIRST. If you even put a spanner on that nut, and the spanner touches any other metal part, you will get sparks. Sparks and petrol is not good - try and avoid it.

Ok, next step is to trace these cables, and examine them.

1) The thick red cable - where does it go to?

2) Check the starter motor for other, thinner cables - take photos, and trace them. Do any go to the key switch? See that red wire above, behind the green arrow, where does that go, for example?

sujsuj

Thanks! I managed to source some jump cables, so I’m going to try that first. I wouldn’t be surprised if it turns out to be a battery issue—like I mentioned, it’s unlikely to be anything else since the mower was working fine a month ago. I was away, and when I came back, it’s in this state.

I’ll try the jump-start option and report back tomorrow. I’ll need to be careful though—I definitely don’t want to risk damaging my car. I’ll watch a few YouTube videos to make sure I do it properly. Thanks again!

WIAWSNB

Remember, when turning the key to test, only do so for a second at the most. That is all it'll take to indicate whether it's working. "Onethousandandone."

Especially when trying a start with the jump leads.

If you keep holding the key in the crank position, it might cause other issues if there's a fault.

See the red rubber cap at the end of the starter motor cable? Trying pushing that up and over that bare terminal to shield it.

Two other tests you can try; 

1) Remove the 25A fuse and see if the key-start still works. Replace. If this fuse is on the supply to the solenoid - ie, removing it prevents the key from activating the starter motor - then check the whole cable length from each side of the fuse, and all the connection you find.

2) Before you try the jump start, try another 1-second key-start after you have first turned on the headlight. Observe the headlight as you 'crank' - does it dim?

sujsuj

Thanks @WIAWSNB, I’ve carried out the following tests:

1. I removed the 25A fuse and tried again — surprisingly, there was no difference. The same sound occurred even with the fuse removed!!

2. As shown in the video below, the light goes completely off when attempting to crank the engine.

sujsuj

Done Jump start exercise with my Mercedes A class. I followed this video to jump start (https://www.youtube.com/watch?v=-CK4i0zpgyw)

My jump start is videoed here..no change at all.
https://youtube.com/shorts/rAl2xjRw0CU

I connected the jumper cables as follows:

• The red cable was connected from the positive terminal of the mower battery to the positive terminal of the car battery.

• The black cable was connected from the negative terminal of the car battery to a ground point on the mower. I tried two different grounding positions — the last one is shown below.

Looking forward to see conclusions from these..? Keen to hear from you all. thanks very much.

sujsuj

WIAWSNB said:

That's helpful.

Yes, the pinion - it's a PINION! - would have been stuck up from your previous attempt.

There are three possible causes:

1) Flat battery. You have charged the battery, but have no way to test it, so it's quite possible that it is faulty - ie, won't 'hold' a charge, regardless of how much charging you give it.

2) The starter motor/solenoid is faulty.

3) The wiring in between the two is faulty.

The blue arrows point to the nuts which presumbly hold the starter motor in position.

The green arrow is where the heavy-duty cable supplies the starter motor. If you trace this, I suspect it'll go directly to the battery? If it does, then it's LIVE, and if you touch it to any part of the mower body (the 'earth'), you will get sparks aplenty, and possibly worse. So, if you do ANYTHING to that wire, disconnect the battery FIRST. If you even put a spanner on that nut, and the spanner touches any other metal part, you will get sparks. Sparks and petrol is not good - try and avoid it.

Ok, next step is to trace these cables, and examine them.

1) The thick red cable - where does it go to?

2) Check the starter motor for other, thinner cables - take photos, and trace them. Do any go to the key switch? See that red wire above, behind the green arrow, where does that go, for example?

I will these tomorrow day time. If my new test output gives any new information , please highlight. thanks

WIAWSNB

sujsuj said:

Thanks @WIAWSNB, I’ve carried out the following tests:

1. I removed the 25A fuse and tried again — surprisingly, there was no difference. The same sound occurred even with the fuse removed!!

2. As shown in the video below, the light goes completely off when attempting to crank the engine.

1) Interesting. So the 25A fuse isn't for the starting circuit. What on earth is it for, then?! Never mind...

2) Ok, that's useful, but I cannot follow the sequence of 'switching'. Ie, I don't know what you are doing with the light and key switches at each stage. There appears to be a solid 'click' when you switch something, and the light comes on - what is this switch? Then you appear to turn the key a further step and there's a loud 'clunk' and the light goes out? What switch is this? And then a further stage again where you appear to turn the key one more step when the starter motor brrrr begins?

WIAWSNB

sujsuj said:

I connected the jumper cables as follows:

• The red cable was connected from the positive terminal of the mower battery to the positive terminal of the car battery.

• The black cable was connected from the negative terminal of the car battery to a ground point on the mower. I tried two different grounding positions — the last one is shown below.

Looking forward to see conclusions from these..? Keen to hear from you all. thanks very much.

Alas, not the outcome I was hoping for.

You appear to have done the correct jumping connection procedure, but I cannot confirm at the car end as i'm not familiar with that battery connection. If you read the manual for the Merc, it should explain where to connect jump leads - have you followed this?

At the mower end, your choice of earth - on that starter bracket - is spot on. And if you connected the positive direct to the mower battery, all should be fine there too. Did you notice any wee sparks as you connected the last clamp?

The fact that nothing changed by having the car battery connected up suggests either (a) you didn't connect the jump leads correctly at the car (please do check what the car manual says) or (b) there is a significant electrical fault on the mower.

By 'significant', I don't mean that it's necessarily serious or costly, but could just a very poor connection somewhere. The fact that the light remains off after trying to start the mower suggests it isn't just in the starter motor, but that's not for certain.

I'm running out of things to suggest from this side of the screen, alas, but please do try and trace all the visible cables to see where they go, and to check their connections. And do double-check you connnected the jump leads correctly at the car end; you probably did, but we need to rule this out.

That top connector - where do these cables go? Is it to the starter motor?

The thick red starter motor cable - where does that go to?

Section62

WIAWSNB said:

Alas, not the outcome I was hoping for.

You appear to have done the correct jumping connection procedure, but I cannot confirm at the car end as i'm not familiar with that battery connection. If you read the manual for the Merc, it shoulod explain where to connect jump leads - have you followed this?

At the mower end, your choice of earth - on that starter bracket - is spot on. And if you conencted the positive direct to the mower battery, all should be fine there too. Did you notice any wee sparks as you connected the last clamp?

I'm trying to think of any way the jump leads could be misconnected in this situation without causing etiher a loud bang or some melty cables.  Nothing is coming to mind....

WIAWSNB said:

The fact that nothing changed by having the car battery connected up suggests either (a) you didn;t connect the jump leads correctly at the car (please do check what the car manual says) or (b) there is a significant electrical fault on the mower.

By 'significant', I don't mean that it's necessarily serious or costly, but just a very poor connection somewhere. The fact that the light remains off after trying to start the mower suggests it isn't just in the starter motor, but that's not for certain.

I don't think much can be concluded from that.  Like you I don't know what sujsuj is doing in the video, nor the specifics of the R28M key positions, but a common arrangement of key positions for ride on mowers is

0 = Stop/Off

1 = Headlight + Ignition (Run)

2 = Ignition (Run)

3 = Start

So the headlight is switched off before the key is turned to position 3, and remains off if the key is released back to position 2.  A photo of susuj's keyswitch might help here, but the sequence in his latest video appears to be consistent with this.

WIAWSNB said:

I'm running out of things to suggest from this side of the screen, alas, but please do try and trace all the visible cables to see where they go, and to check their connections. And do double-check you conencted the jump leads correctly at the car end; you probably did, but we need to rule this out.

My early guess was the starter motor, and remains that.  I think sujsuj is probably in a position where the next move is to either -

1) Shell out for a new starter motor and hope that expense fixes the issue.

2) Get professional help to diagnose and repair the mower.

The advantage of 2 is it may save the cost of a new starter if the fault is with something else, but the disadvatage is it likely costing more than a new starter motor for a DIY swap.

Given the engine has been pressure washed earlier in its life, and given the amount of corrosion on the flywheel, it isn't unreasonable to think the starter motor has just had enough.

WIAWSNB

SS, if you are confident the jump leads were connected correctly at the car end - so it ain't a lack of battery power - then are you up for removing the starter motor, and bench-testing it?

If so, let us know, and we'll guide you.

Unless you find a likely cause by tracing the wires to see where they go, and to check their connections (do this first), then it usually comes down to eliminating components one by one.