yanmar b08-3 won't start

[sandbags89]

Hi all,

new member just joined in search of a few clued up people of the plant world...

I have a mini excavator (yanmar b08-3) which will not start up and i can't for the life of me figure out why. It turns over, smokes out the exhaust but just won't start up, even when it seems like its just about to.

First happened months ago, was being used no problem, turned it off to have a break, then it wouldn't turn back on. Same thing, would turn over but wouldn't start. Was confused, checked for any obvious reasons, but eventually just topped it up with diesel in case (even though it had plenty of fuel in there) anyway it then started up so didn't think much of it. Parked it up, few weeks later got it out and used it as normal again. Noticed it performing a little sluggish, when pushing or using the arm to lift a more heavy/stubborn load it would sound like it was about to stall, so id quickly stop before that happened. Eventually I made the mistake of not stopping in time and it stalled in the middle of the garden and wouldn't start up. Tried topping with diesel again but no luck this time. Spent ages trying to start it but no luck. So left if for an hour and tried again and luckily got it to start, so quickly parked it up....and it hasn't moved since. Haven't been able to get it going for few months.

From my own limited knowledge and through bit of research online, I assumed it had to be either no fuel, engine not breathing properly, air in fuel, or water in fuel. I have done the following:

• The smoke from the exhaust leads me to believe it has fuel, but i checked anyway and fuel seems to be making its way through the rights hoses and getting to the injectors ok.
• Checked all hoses, no blockages
• checked injectors for blockages or gunk build up (these were also replaced not too long ago)
• changed fuel filter and cleaned out bowl
• changed pre-fuel filter
• emptied fuel tank and topped with fresh diesel
• new air filter
• changed oil and filter while i was at it
• new glow plugs
• bled air from fuel (although may be helpful to know correct procedure for this. I done so by cracking a nut that looking like it was for bleeding purposes. also tried cracking the nuts on the metal fuel lines connected to the injectors)
• charged battery (and tried starting with a booster pack)

Sorry for the long-winded post, but just trying to paint the full picture.

Would appreciate any advice to get this working again!

thanks in advance

I have a vid of the start up but can't figure out how to upload it. Doesn't allow me to provide the link

 

[sandbags89]

video is on youtube... /shorts/nupX-NUf0JA

 

[V8Druid]

welcome .... sounds like a lil' sod .... is the fuel tank breather clear? usually in the cap
could have a fuel hose inner collapsing and quietly starving the engine of fuel over time as it gets ever tighter in the line
could be a little gauze filter in a banjo union blocking up ?

insufficient compression in a compression ignition (diesel) engine ain't good .. neither is trying to start it with an iffy/low/poor battery as it won't spin over fast enough to develop sufficient compression to make the diesel go BANG

you've certainly covered a lot of bases in your description

"charged battery (and tried starting with a booster pack)" makes me wonder about your battery - is it up to the job of flinging it over fast enough. booster pack may not give a naff battery enough beans

 

[muckyman]

Easy start lots of people hate it but it works wonders

 

[Quattromike]

Have you tried replacing the starter motor. Occasionally they get tired and don’t turn over fast enough

 

[Mick-the-fitter]

2 things on the B08-3 fuel stop solenoid, and Aux pedal, firstly if you remove the stop solenoid from the back of the pump. Try and start it! If not starting, try Aux pedal because they out in all weathers they seize up, just try moving the pedal when trying to start!

 

[sandbags89]

morning, thanks for your replies:

welcome .... sounds like a lil' sod .... is the fuel tank breather clear? usually in the cap
could have a fuel hose inner collapsing and quietly starving the engine of fuel over time as it gets ever tighter in the line
could be a little gauze filter in a banjo union blocking up ?

insufficient compression in a compression ignition (diesel) engine ain't good .. neither is trying to start it with an iffy/low/poor battery as it won't spin over fast enough to develop sufficient compression to make the diesel go BANG

you've certainly covered a lot of bases in your description

"charged battery (and tried starting with a booster pack)" makes me wonder about your battery - is it up to the job of flinging it over fast enough. booster pack may not give a naff battery enough beans

little sod indeed!

can't see the fuel breather you mention. I attached a photo of the tank and cap.
the hoses appeared to be okay, pullet them all of and blew through them to ensure no blockages.
sorry you've lost me with the banjo union, is that the nut I used to bleed the fuel, above the fuel pump in the images?

yes i forgot to mention compression earlier. I have read that could also be the issue, but i am unsure of how to diagnose this if im honest. I had a compression tester for one of my old cars but the fittings are not the same. Perhaps i could try to find a cheap kit somewhere for diesel. How would I know what compression it should be, and if it is low what would be the next step/the cause of this?

Easy start lots of people hate it but it works wonders

yes, went to give this a go but i literally had one pathetic little squirt left in the can. i'll go get myself some more and have a proper go.

Have you tried replacing the starter motor. Occasionally they get tired and don’t turn over fast enough

didn't think of the starter motor, as it sounds like a strong little bugger giving it everything. Same with the battery, i have put it to charge over night, tester says its fully charged, and sounds it tbh. Also attached it to a larger van battery and had same issue.

One thing i noticed, is that sometimes when i crank it, it tries for a few seconds then speeds up slightly like its going to turn over but it never does.


another thing i forgot to mention is I did check the stop solenoid which is also working as it should, and i checked all the fuses i could find.

Also, i checked in the manual and it says one of the causes could be a slow blow fuse. When i go to check this fuse according to where it is in the manual diagram, it doesn't exist. there is no fuse to check, instead it is what looks to me like a relay. With an electromagnetic switch. It was more or less a sealed unit, but i managed to pop it open to look inside and confirmed no fuse inside. When i turn they key the stop solenoid activates making a click noise, and the same time the electromagnet relay switch activates for 2seconds then deactivates... not sure of its purpose.

thanks for input so far guys

 

[Mick-the-fitter]

The relay provides the throwing current for the stop solenoid when the starter is energised, it’s timed because the solenoid has a run coil from the ignition. If you remove the stop solenoid you can run it, to stop it just push the end of the rack in with your finger, if this works you may have a solenoid or timer relay issue!

 

[sandbags89]

the solenoid seems to be working bud. I removed it whilst still wired in, turn the key and the pin retracts

 

[Mick-the-fitter]

Did you try running the engine with it removed?

 

[Monkeybusiness]

@Mick-the-fitter’s aux pedal is a good shout.

 

[Maxus]

If its getting fuel and air, probably to be a compression issue. My guess is that the starter motor isn't providing enough oomph to fire it up. There could be other factors that are resulting in low compression, possibly coked up valves that aren't seating properly as a result or worn piston rings..

I'd try getting it going with easy start and use a valve cleaner (stuff you squirt into the air intake when it's running) and see if that helps as this is the cheapest thing to do. Then I'd replace the starter motor and see if that helps.

I'm no expert btw... Just having a stab in the dark!

 

[TiltyShaun]

We had a little bobcat mini that was a pig to start. Compression compression compression.

 

[Mick-the-fitter]

That’s where the engine will end up o think, in the dark at the back of the garage, easy start not the best for modern engines

 

[Tacitus]

It sounds like its starving for fuel. Loosen the fuel cap to make sure it's not the breeder.

 

[sandbags89]

Did you try running the engine with it removed?

tbh i can't recall if i tried starting it whilst it was out. I can give it a go. Although as I mentioned before, when i pulled it out and turned the ignition, the pin in the solenoid seems to retract no problem, and stays until i turn key off. I pushed the pin to see if it goes in further but that seems far as it goes. If i start it without the solenoid, will it piss out fuel or something?

If its getting fuel and air, probably to be a compression issue. My guess is that the starter motor isn't providing enough oomph to fire it up. There could be other factors that are resulting in low compression, possibly coked up valves that aren't seating properly as a result or worn piston rings..

I'd try getting it going with easy start and use a valve cleaner (stuff you squirt into the air intake when it's running) and see if that helps as this is the cheapest thing to do. Then I'd replace the starter motor and see if that helps.

I'm no expert btw... Just having a stab in the dark!

gave it a try with easy start yesterday, no luck. If anything made it a bit worse for some reason, start up sounded more sluggish maybe was a battery issue, will give it another charge up.

new starter seems to be about £150. i'll see if i can try any cheaper options first. i've ordered some new fuel hoses in case there are any air leaks. the new ones are also transparent so I can see if fuel is passing through as should.

It sounds like its starving for fuel. Loosen the fuel cap to make sure it's not the breeder.

i'll give this a try to

 

[Mick-the-fitter]

Are you sure your pedals and levers are not operating any hydraulics?

 

[sandbags89]

Are you sure your pedals and levers are not operating any hydraulics?

doesn't seem it. i've given them all a wiggle to make sure it wasn't one of them bogging down the power...

 

[CPS]

Are you sure your pedals and levers are not operating any hydraulics?

I'd be aiming there too

 

[V8Druid]

tbh i can't recall if i tried starting it whilst it was out. I can give it a go. Although as I mentioned before, when i pulled it out and turned the ignition, the pin in the solenoid seems to retract no problem, and stays until i turn key off. I pushed the pin to see if it goes in further but that seems far as it goes. If i start it without the solenoid, will it piss out fuel or something?


gave it a try with easy start yesterday, no luck. If anything made it a bit worse for some reason, start up sounded more sluggish maybe was a battery issue, will give it another charge up.

new starter seems to be about £150. i'll see if i can try any cheaper options first. i've ordered some new fuel hoses in case there are any air leaks. the new ones are also transparent so I can see if fuel is passing through as should.


i'll give this a try to

give it a new battery ....... pi**ing about with tired batteries never ends well .... you know then that, that is not the issue and if the starter is OK it'll be flinging it over ... unless as also said, you have a service not in the neutral position and loading the pump from the off.

you also need to be absolutely certain all your earth points are clean and making a perfect connection .. bat. to chassis, chassis to engine, bat to engine/starter, if it has one .. they all have to conduct a decent amount of current on start and crap connections won't ...
also make certain your +ve connections are all A1 ...

does it have an isolator? they deteriorate over time/usage and internal poles can corrode in them.

As said previously ... no amount of 'sluggish' churning over, is going to make a compression ignition (diesel) engine fire ... the fuel/air charge has to be compressed rapidly, to generate the ignition ...

which also brings us back to a possible compression issue if you're able to fling it over and it still not start.

The amount of fuel you've been putting into the bores, will by now have washed them clean of any lube, which also won't help the cause... although a PITA, I'd pull the injectors and give each pot a couple of cc,s of engine oil squirted in .. once you have got it whizzing over BUT NOT BEFORE.

AND check your sump for diesel contamination in the oil ... that will also degrade the lube and hence the compression .... the piston rings need good lube to seal on the bore