Westwood S150 - Will start but engine dies as soon as blade engages.

[WindyinSancreed]

It is about 8 years old with a mulching deck. Has had some interesting electrics for some time now.

Starts fine but as soon as I hit the blade engage button, the engine cuts out without any obvious attempt to engage the deck.

What it is not:

1. Rubbish battery. It has recently been replaced and trickle-charged.
2. Seat safety switch. Have shorted it to test.
3. Blade engage button. Has been replaced.
4. Something jamming the blade. Turns fine.

It used to be the case that if I ran it for 5 minutes and then engaged the blades it would work, but I ran it 15 mins yesterday with no luck.

Another symptom is that if I use it for a bit then turn it off for 5 mins the engine just dies for no reason. Can always be restarted immediately and then after a bit runs fine.

Two repair shops have failed to find the fault.

Help! There are beers in it.

Thanks.

 

[Nearly]

scale built up in the carb from evaporated fuel?

@TripleSix

 

[RushesToo]

Try these chaps - there isn't much they don't know about mowers:

Lawn Mower Sales and Servicing - GSS

www.gssgas.co.uk

They may help over the phone.

 

[Tony1989]

Is it a v twin engine?

 

[startinghandle]

Problems with valve seats caused by low sulphur fuel ?
Spark plugs?

 

[agrotron]

Had exactly same problem on t1600. Found when the switch to power the deck was pressed it stopped the power going to the fuel solinoid so I just bypassed the switch so solinoid had power all the time. Let us know if you figure it out.

 

[Lincsman]

Seems like an electrical issue to me, the simplest ride on has multitude to cut outs and switches, you will have to investigate further, by bypassing temporarily

 

[robbie]

When our ride on done that it was because the electrical system wasnt charging enough. It would keep the battery charged for starting fine but when you engage the electro magnet for the deck clutch it was starving the electronic ignition of power momentarily causing it to loose the spark to the plug.

 

[robbie]

When our ride on done that it was because the electrical system wasnt charging enough. It would keep the battery charged for starting fine but when you engage the electro magnet for the deck clutch it was starving the electronic ignition of power momentarily.

 

[TripleSix]

Unplug the 2 wires from the blade clutch and see what it does then.

Also try with the ignition, give the starter a little flick but don't let it start.
Then press the blade engage button, does the clutch make a good clunk?

Does it still turn when engaged?

 

[f0ster]

you need to be able to see what is missing when it cuts out, get one of the spark testers that fit inline with one of the plug leads, you will now be able to see if the spark disappears, if it does you now have somewhere to start looking for the fault,

 

[Dry Rot]

I had problems with my Honda quad. Finally, took it to the main dealers who changed the CD! unit. I knew it wasn't that as I'd already replaced it as I explained to heir mechanic. But apparently the mechanic had left without passing on the message!

The fault turned out to be a wire pulled partially out of a multipin connector so a poor connection leading to a weak spark.

When I told the main dealers what the fault was and told them they had replaced a perfectly good CDI unit, they refused to give me a refund on the unit they'd put in. I suggested they migt put it back on the shelf and use it for another repair but they prefer to create bad customer relations. Won't be using them again.

^^^^^ to the spark tester. I could see mine had a weak spark but the main dealer couldn't. Idiots!

 

[Dave W]

As @TripleSix says, you need to decide if it's electrical or engine problem. Either disconnect the electric clutch or drop the belt off to the deck. If it still cuts out it is definitely an electric issue.
If it doesn't cut out I'd put money on a bad plug. I've had a couple of vtwin engines that started and ran sweet with no load but were gutless under load. Only running on one cylinder.

 

[DrWazzock]

Big inrush current to those electromagnetic clutches. Bad connections somewhere could be dropping a lot of voltage for just long enough to kill your ignition. Check battery lead connections., earth connection etc and onwards . Simple things first.

 

[Tony1989]

If it’s a v twin I would run it and pull 1 plug lead off at a time and see if they differ, we have had loads with coils gone running on 1 cylinder perfectly well until you engage deck and the extra load will cut it clean out.

 

[Netherfield]

Loose connection on PCB, dodgy ignition switch.

 

[DrWazzock]

The other thing is maybe check the coil resistance of the electromagnetic clutch. It might be shorting to earth and pulling a much bigger current than it should, pulling system voltage down. Connect a voltmeter to low voltage side of ignition coil and see if it drops away when you engage the clutch.

 

[WindyinSancreed]

Thank you all for your replies. I think we have a diagnosis.

We thought that we would target the blade deck switch first. When we took off the dashboard to get to the switch, it became clear that there is a bad connection somewhere in the loom which sits behind there. At first the mower would turn over but not start. The it was completely dead when I turned the key. Then the display flashed on and off. With a bit of wiggling it worked again and the deck would start no problem.

But it is clear that there is something not quite right somewhere around the loom/PCB. If you look at it, it appears as if the loom has been taken off in the past and not quite fully returned to its rightful position. It won't go any further in. I put the dashboard back in gingerly but no doubt, just when I start my major cut in 3 weeks, it will act up again. Don't fancy mucking around with the electrics further so it is heading in for someone competent to sort.

As I say, the electrics on the mower have been interesting for quite some time and this would explain all the issues I have been having.

Thank you all again. If there is a central kitty for message board costs, more than happy to contribute to it.

Simon