Can't start Honda GXV140 HRD535 lawn mower

[MoreWellie]

Damn thing is so close to starting but I just can't get it to run and the grass is growing so I thought I would ask if anyone had useful suggestions for things I might have missed

Things I have tried, not necessarily in this order
1. clean air filter (tried starting without it)
2. replace fuel
3. strip and clean carb, including remove jet and poking all the holes
4. check valves are not gummed up and both move ok by finger pressure
5. check compression which is 130psi
6. checked and gapped plug (also made sure it is sparking)
7. replaced plug with new one
8. checked blade doesn't revolve when start cord pulled gently
9. removed exhaust and checked but there wasn't a spark arrestor fitted

it is so close to running. when using the pull start, if I pull a couple of times with choke on and then pull it back to full throttle, where the choke is just off, the engine will fire and keep firing for perhaps five seconds but peters out

in desperation I even tried easy start through air intake but that didn't make any difference

 

[cumbriasteve]

Fuel cap vent blocked?

Although they tend to run a bit longer before cutting out if that's the case.

 

[MrFluffy]

Have you checked the flap that activates the throttle isnt clogged and the govenor spring is still fitted, and that the mechanical start cutout is activating properly (my gcv135 pedestrian mower wont start but makes occasional pops and farts if the handlebar safety bar isnt adjusted properly).
The other thing is have you had both the main and the brass section above it out the carb, you push the tube out from inside the carb throat and that has tiny drillings that gum up too.
When mine wouldnt start with a bad carb, I could tip fuel down the carb intake and it would fire up a bit then cut out again when it had used that fuel.
I bought a replacement carb for it because it was cheaper than a gasket set, then when it turned up it opened the "wrong way" for both throttle and choke linkages, and when I contacted the seller he said it was a "compatible unit with some adaption needed". I ended up rebuilding my original carb with the main jet out the crap copy, but caveat emptor on those replacement "equivalent" carbs on ebay...

 

[eSCHEn]

Agreed, vent cap usually is a longer time to failure.

Could be fuel line blocked/perished internally? Just as it's about to die try backing off throttle and back on again quickly. The pulses allow it to clear. Car is doing this very thing right now!

 

[voipio]

Could be the fuel pump membrane has perished, or ruptured.

 

[MoreWellie]

Fuel cap vent blocked?

forgot I had tried running with the cap pretty much unscrewed

have you had both the main and the brass section above it out the carb

yes and used jet picks to make sure all the holes are clear plus used carb cleaner through the remaining part of the body

Could be fuel line blocked/perished internally?

possible although there are no signs of rubber in the float chamber. I did check that turning the tap on lets the fuel run freely out of the hose that fits to he carb

can check with drain bolt if fitted or by cracking off the retaining bolt

yes it does and after cleaning the carb out and turning the fuel tap on you can hear the fuel gurgle in to it

I did wonder about timing but it doesn't seem to be adjustable and I haven't had the engine apart any further than the rocker cover

I did find some weird thick black stuff inside the rocker cover looked a bit like strings of silicone but cleaned off with wd40 ok

I read that the rotostop mechanism is prone to causing issues but presumed I would see the blade move when pulling the start string if this was the case

 

[8ob]

Its worth checking the oil alert system, they can mess about and cut ignition even if the oil is up to level.

Bob

 

[MoreWellie]

Its worth checking the oil alert system

From all the reading I have done I don't think this engine has an oil level automatic cut

also given that it fires for a number of seconds it would seem that the ignition is connected ok

I have replaced the oil as part of my lets do everything so I know it is clean and at the correct level

 

[8ob]

I don't think it's an oil alert equipped engine either. Not many of the gxv series were (unlike the gx).

I sort of moved on to possible ignition issues because Mr Wellie tried ether on the engine and it still never fired, with the fuel system pretty much gone through its pointing towards an ignition problem. Easy start will find a spark if there is one in most cases.

Bob

 

[armalites]

Some of these mower engines have a keyway that is there to protect the engine when the blade hits something, what then happens the key gives and the timing is all over the place and it won't start, as you say it sounds like its'almost there. Had it on a mower of mine when I hit some metal the kids left in the grass.

 

[dobbslc]

I had an RD125LC that did exactly that! I couldn't find anything wrong with it but still it wouldn't start. Massive backfires every now and then though!
The key had sheared and the timing was out. I had a mate years later on with the same model that had done the same thing

 

[CKJDJK]

Are you sure the replacement fuel is new? Petrol goes off very quickly these days. Re the carb. Try cleaning the jets again with 50/50 mix white vinegar and water. agitate frequently or use an ultrasonic bath. Wash of and blow through. Refit and retry. Check all the drillings are clear in the carb body. Check carb gaskets are good. Check the spark. It should occur slightly before TDC if timing correct. As already said, check governor springs and levers work correctly. Attached hopefully will be a GCV 160 manual, it may help.

 

[CKJDJK]

My experience is that some engines are very sensitive to petrol quality yet some cope with stale petrol. Just something to eliminate. I've got an old lister D type that will virtually run on old manky petrol compared to my chain saw that needs fresh petrol to run properly.

 

[MrFluffy]

I put the 11 month old fuel I drained out the 101 in the strimmer and it wouldnt start. I drained it and added fresh instead and its happy again.
I'm currently using the 30l or so of gone off petrol in the sit n ride mower and the old massey tractor instead both of which are tolerant of crap fuel.

 

[andymfell]

[QUOTE="MoreWellie,

3. strip and clean carb, including remove jet and poking all the holes
[/QUOTE]

have you removed and cleaned the pilot jet
you have to remove the throttle stop screw completely
and the jet is the black plastic thing that has two flats on it and is installed vertically into the carb body
it is pushed into the alloy body ( not threaded) retained by a small oring
it has a 0.3mm orifice that links to the cross drilled 2mm hole that often clog

 

[MoreWellie]

Have you actually checked there's a decent spark at the plug?

it looks ok with the plug out and I used an old fashioned neon timing light to check it was sparking with the plug fitted and that looked normal as well

Are you sure the replacement fuel is new?

yes, bought it myself, took an empty can and came back with a full one, that said I have always previously started a new season with last years petrol but turn the tap off and run the mower out when I leave it

Attached hopefully will be a GCV 160 manual

Thank you for that, engine is quite different but may well help with processes and other diagnostics. I have looked for a UK source to buy the manual for this engine but so far drawn a blank

Some of these mower engines have a keyway

worst has been the odd small stone but a good thing to check as it does feel timing related

I found the valve clearances online yesterday and should have some time to check those tomorrow

Thank you for all the posts, even though the grass is getting rather long the main thing is not wanting to be beaten by the machine!

 

[MoreWellie]

have you removed and cleaned the pilot jet

no but I will now and the main nozzle air path looks a good thing to check as well

Thank you very much for the chart

 

[MrFluffy]

Mine wouldnt start again today, and it turned out to be that jet blocked under the screw underneath the screw for the throttle stop. Most satisfying when I unblocked it and a squirt of cleaner into the jet from the screw area came out the flange area of the carb, even more satisfying when it started first go afterwards.

 

[Turbo]

in desperation I even tried easy start through air intake but that didn't make any difference

A simple test to diagnose starting problems is to squirt some wd40 down the intake & try to start it. If it starts you have a fuel problem, if not you have a spark or timing issue. Easy start might evaporate too quickly to work, try the wd40.

For an spark problem first thing to check would be a partially sheared flywheel key.
Even though you have a spark at the plug it may not be strong enough & get 'blown out' by the compression. Check your plug gap & the coil to flywheel gap.