Purchased as a project 

Qualcast XSZ53C-SD-E with the Briggs & Stratton 775iS engine, a non runner, I stripped and cleaned the carburettor and the jets, it now starts but has 3 other issues.



I have fixed a few mowers in the past but it's my first experience with the electric starts.

Issue 1: The engine will never start on the first turn of the key (even with easy start) - it starts perfectly on the second turn.

Issue 2: When it first starts it revs up and down for 20 seconds then runs lovely.

Issue 3: After it has been ran for 20 minutes it won't start again until it cools down - then when it does start get a puff of white smoke.

Replaced the oil and spark plug before doing anything to it, waiting for a new air filter so will see if that makes any difference.

Plan to remove and clean the coil but I'm thinking the issue could be something to do with the auto choke so will investigate that further when I get inside it.

Hi Rach, and welcome to TGMF.   

I suspect (and I'm only guessing based on the slight hunting when you first start it) the engine is running a bit too lean, and when warm the thermal device is holding the choke completely off as it should. But because it's running a bit lean it wants a little choke to restart. Hence why it needs to cool down first.

When you get to looking at the problem a photo of the carb and linkage might be interesting to see. 

Thanks for the welcome Mick 

That's a good point, I didn't move the adjuster screw but I don't know if the previous owner has done any tinkering, I have attached a couple of pics of the carb which were taken before I removed it, I'll get some clearer shots shortly but it will give you an idea of the linkage

Quote from: Mick on April 28, 2023, 07:20:23 PMHi Rach, and welcome to TGMF.   

I suspect (and I'm only guessing based on the slight hunting when you first start it) the engine is running a bit too lean, and when warm the thermal device is holding the choke completely off as it should. But because it's running a bit lean it wants a little choke to restart. Hence why it needs to cool down first.

When you get to looking at the problem a photo of the carb and linkage might be interesting to see. 

sounds like the coil.. when it gets hot it stops working.. get an in line tester and when it stops working put the tester on and see if you have spark .with regards to the hunting use a micro drill and drill out the bowl jet

Coil is a possibility and can't be ruled out, they're certainly not made like they used to be.

strikes me with this scenario is the fact it hunts slightly on start up, that indicates it's on the lean side, and these things sometimes like a bit of choke to restart.  Obviously this can't happen with the automatic choke, and it's being held off by the thermal device.

I would certainly go down the cheaper route first and make sure all jets and carb are spot on.

Managed to get this from eBay for £13 with free delivery



I had already changed the oil and plug but it was going to cost £13 for a genuine filter and pre filter so thought might as well take the opportunity to get the bits and a few spares for the same price.


Does anyone know the original part numbers for carb gaskets?
 


I believe the gasket with the yellow arrow is: 691894
(https://www.mowermagic.co.uk/acatalog/Briggs-and-Stratton-Gasket--air-cleaner--795629-BP691894.html9)

But I can't find a part number for the one with the red arrow or a seal for the bowl.

I forgot to mention the float had a layer of white cream on it and the inside of the bowl has gone dull and matte like - likely to be the effects of Ethanol as mentioned in Mick's excellent Look After Your Fuel guide.

Following this thread with interest. We have a non starter 775is which we picked up at auction on a decent Atco. Started and ran fine at first... now nothing and we've been working our way round plugs, carb, coil etc.

Interested in the comments about the choke - should the spring arm running from the choke to the car be very "loose and jiggly", requiring the slightest touch to move it back and forth? Ours is very loose like this and I don't know whether this is normal or whether the spring mechanism inside the choke might be banjaxed.

@CoffinDodger

They use a fairly light spring on the choke linkage so it will be able to move easily.  As long as it's close when cold and engine stopped it should be fine.  Make sure the thermal device isn't sticking and holding the choke open when cold, and make sure it's holding the choke off when hot. 

Also you'll notice as soon as the engine starts and the governor kicks in it will also nudge the choke off slightly, so correct setting the governor is also important. I've seen these set wrongly by people tinkering, closed down more than they should be and the choke not closing because of it.

Seems I made a slight mistake with my eBay purchase, the spark plug in Engine Care kit isn't the same as the one listed for my mower,

XC92YC is what I have, 992304 is in the kit



The electrode on my spark plug (on the left in the pic) seems to be bent out a bit.


I cleaned the coil up today:


Something I noticed is that when the bolts are loose the coil moves from side to side - I don't know if it makes any difference as long as the gap is still 0.010 with a feeler gauge.

When refitted, 1st turn of the key no attempt to start, 2nd turn no attempt to start, 3rd turn it starts, revs up and down a few times then starts to run fine but has a strong smell of fumes.

Any chance a worn carb bowl seal or carb gasket could cause this?

I don't think it can be the carb jets as I spent ages cleaning each jet by sliding wire up them and then blowing them out with the carb cleaner straw too

Quote from: CoffinDodger on May 03, 2023, 08:08:48 PMFollowing this thread with interest. We have a non starter 775is which we picked up at auction on a decent Atco. Started and ran fine at first... now nothing and we've been working our way round plugs, carb, coil etc.

Interested in the comments about the choke - should the spring arm running from the choke to the car be very "loose and jiggly", requiring the slightest touch to move it back and forth? Ours is very loose like this and I don't know whether this is normal or whether the spring mechanism inside the choke might be banjaxed.

Mine is also loose and jiggly, at first I wondered if it had come unattached,

Does yours not start with a spray of easy start?

Quote from: Mick on May 04, 2023, 07:27:11 AM@CoffinDodger

They use a fairly light spring on the choke linkage so it will be able to move easily.  As long as it's close when cold and engine stopped it should be fine.  Make sure the thermal device isn't sticking and holding the choke open when cold, and make sure it's holding the choke off when hot. 

Also you'll notice as soon as the engine starts and the governor kicks in it will also nudge the choke off slightly, so correct setting the governor is also important. I've seen these set wrongly by people tinkering, closed down more than they should be and the choke not closing because of it.

Thanks Mick, I've checked the choke and it is able to move easily - I inspected it with the air filter removed, and it has a full range of movement with the valve closed when cold.

I checked the governor and my son had tightened the adjustment screw the other day - I've backed it off now to give it the full range of movment.

Thanks Rach, I didn't have any easy start in stock,so I  just got some - and No, it will still not start with easy start.

I had suspected the spark, but we can see a spark with the spark plug held against an earthing point on the engine frame.

I have replaced both the spark plug and the coil pack with the correct briggs spares.

Is there any way it could be getting a spark when the plug is outside the engine but not doing so when the plug is refitted, and the engine covers are all back on?

I've checked the cut-out wire and it seems to be sound and connected correctly. The cut out switch appears to be fine too.

Stumped.

[edit - spelling]

Quote from: CoffinDodger on May 06, 2023, 11:04:49 AMStumped.

Have you checked to see if the flywheel key is sheared?  If it has then you will get a spark but it can be so far out of time that it won't fire.
 

Quote from: Mick on May 06, 2023, 11:16:22 AM

Quote from: CoffinDodger on May 06, 2023, 11:04:49 AMStumped.

Have you checked to see if the flywheel key is sheared?  If it has then you will get a spark but it can be so far out of time that it won't fire.
 

Yes, I've even pulled the flywheel, to check for problems beneath with the cut-out wire.

Quote from: CoffinDodger on May 06, 2023, 11:50:26 AMYes, I've even pulled the flywheel, to check for problems beneath with the cut-out wire.

Strange.. There was obviously a reason it went to auction.  What about valves, have you taken the cover off and checked them.  Make sure one of the valves isn't stuck open? Or a tappet jumped off a pushrod etc.
 

Well, in for a penny...

I removed the valve cover, and rotated the engine by hand. The movement of the springs and push rods seemed fine - I'm at the limit of my experience here but it didn't seem obviously wrong. There was a small amount of fresh oil inside the case.

I've just removed and re-checked the carb and bowl, checked there is spark, reassembled and tried starting with easy start.

Nothing. The starter motor rotates it well and at a consistent good speed for starting.

Son asked if it's getting good compression - Not sure how to even check that.