Almost new RobinSubaru EH035 suddenly stopped and will not restart.

Discussion in '4-Stroke Engines' started by Oban, Feb 17, 2012.

  1. Oban

    Oban New Member

    I've just fitted a new RobinSubaru EHO35 to a Staton crankshift kit.
    It has worked fantastically but now I've hit a problem.
    Motor has only done about 6 hours - always started first time and ran beautifully.
    Had gone about 3 miles and was heading up a hill on about 3/4 throttle.
    Suddenly the motor cut totally, no coughing, didn't bog, just as if I had hit the kill switch.
    Haven't been able to restart it since.
    Took the kill switch out of the circuit.
    Spark at plug looks good.
    Plug does not seem to get wet with fuel even after numerous starting attempts.
    I've stripped the carb and checked all the filters and jets - all seem brand new and clear (as they should)
    Why might there be no fuel (obviously I've filled the tank and the priming button brings fuel to the carb)?
    When the bike stopped it just didn't feel like fuel starvation.
    Unfortunately returning the motor to America is not an option (I live in Scotland)
    Could anybody help please?

  2. Silvaire

    Silvaire Member

    Particularly because the plug is not wet at all, I would suspect a fuel problem.

    Start with the basics - which is what any small engine shop anywhere would do.

    Is there spark? If so, try priming the engine and see if it will run on a prime. Take off the air cleaner cover, and pour about half a teaspoon of gas down the intake. Have the throttle open when you do this. If the engine runs for a few seconds and stops, you have some sort of a fuel issue.

    Assuming it is a fuel issue, the problem could be anything from a pinched fuel line, a clogged filter or jet, a plugged fuel cap, and any number of other things. If you don't feel capable of figuring it our, any local shop that is competent to repair weed eaters and the like should be able to sort it out fairly quickly.
  3. Oban

    Oban New Member

    Thanks for that Silvaire,
    I'm reasonably competent with small engines although I must admit I didn't know about feeding fuel directly into the air intake.
    I started with basics
    Good spark at plug
    good compression
    tried with fuel cap off and on
    suspected fuel because plug was almost dry
    blew through intake pipe from tank to carb
    stripped carb and made sure all jets were clear

    I tried your trick of squirting fuel into intake (with throttle wide open)
    still no response whatsoever (plug wet with fuel)

    What would a small engine shop try now? Am I missing something obvious?
  4. BigBlue

    BigBlue Active Member

    Check the spark plug really good and make sure it is not cracked. Did you check for spark with the plug in the head or out of the head with the wire connected? I had a brand new spark plug cracked once and was causing me all kinds of headaches.

    AKA: BigBlue
  5. Silvaire

    Silvaire Member

    First, I take it as a given that the engine has reasonably good compression. If not, that needs to be looked into before anything else.

    Doing the test I suggested is about as basic as it gets, but it certainly doesn't bypass every possible problem.

    If it doesn't fire with this prime start test - and when you pull the plug it is still wet - blow off any fuel on the plug and try starting it again. I'd probably repeat the whole process again just to make sure you had sufficient fuel, and that you haven't flooded it with excessive fuel. Also, use full throttle when you try to get it to fire off a prime.

    If still nothing, I would suspect the condition of the spark plug or the quality of the spark. You should see a nice strong blue spark. I do assume the plug is clean? Try another plug if you have one. If a change of plug does not fire a prime, I would next suspect the ignition module. I don't know of an easy way to check one. I've found that they work or they don't work - or that they will work intermittently...

    Another rather remote possibility is that the flywheel key has sheared and the spark timing is now incorrect. I would look long and hard elsewhere first, but it is still a possibility.
  6. Happy Valley

    Happy Valley Active Member

    Between yourself and Silvaire's suggestions it seems most bases are covered, spark and fuel usually equals go, though it can be hard to confirm the fuel issue.

    Perhaps worth a mention, there is a hidden filter in the carb, a small round metallic screen, found when you separate the carb body. With so few hours on the engine I doubt it's an issue but you never know, it might have picked up some lint or debris.
  7. Oban

    Oban New Member

    Happy Valley - yes I checked the metallic screen when I stripped the carb - totally clean.
    Silvaire - compression seems okay
    Tried the prime start test a few times - cleaned and dried the plug between times.
    Spark looks strong and blue, plug is clean, looks brand new (which it is!)
    I did start to wonder about the spark timing.
    Big blue - checked for spark with high tension lead connected and touching plug to the cylinder head.

    Even though I cannot get it to start now, what is really confusing me is the manner in which it failed - an instant stop exactly as if hitting the kill switch. Whenever I've had fuel problems in the past it has always been a gradual (over a few seconds) decline.

    Thanks again guys for your help, I'm tearing my hair out here (and it's pouring it down with rain!)
  8. Happy Valley

    Happy Valley Active Member

    My bet is something very simple. Try a new plug.
  9. Silvaire

    Silvaire Member

    Yes, I would too. Even a "new" or "new looking" plug can fail.

    When trying to diagnose an engine performance issue, installing a new plug is the most sensible and most economical first thing to do before digging into an engine looking for other causes.
  10. BigBlue

    BigBlue Active Member

  11. Happy Valley

    Happy Valley Active Member

    You bet, eliminate the simple and obvious first. Sometimes hiccups like this, particularly on a near new, quality engine like a Robin, get over-thought in forum threads.
  12. HeadSmess

    HeadSmess Well-Known Member

    you done just about everything...hmmm

    no mention of checking valve clearances. with a 4 stroke, that needs a peek... 4-5 thou, .1 mm...

    checking that the valve gear is actually working is a good idea

    the ignition timing can only change if the flywheel key has sheared.
  13. Mike St

    Mike St Member

    Maybe you can try this. Spray starting fluid directly into the carb and see what happens.
    For cold engines that have never been started, this works, but I do think you have some kind of basic problem. Let us know if you find it.
  14. Oban

    Oban New Member

    Swapped the spark plug for one that was working in another engine - no luck I'm afraid.
    So I'll check the valve clearances Headsmess
    Chris - I found that link when searching but I'm afraid it doesn't help - I've tried it with the kill switch in and out of circuit - also i get a good spark when the switch is on and nothing when it's off - as you would expect.

    It's pretty depressing having to start thinking about stripping down a brand new engine after 6 hours!
    I guess I've learnt my lesson to buy locally and I could have taken it back under warranty.
    If the valve clearances seem okay I'll have to bite the bullet and take it to the local engine shop to check that I haven't forgot anything obvious.
    Thanks for your ideas though...
  15. Oban

    Oban New Member

    Rawly old - stripped the carb and blew through all the jets, fine mesh screen internally and external filter both totally clear. all diaphragms intact and appear to be working as they should.
    Oil rich mix? I'm confused - it's a four stroke....
  16. rawly old

    rawly old Member

    Dry plug, if the carb's not wet the 1st thing to check is the filter
    before tearin into carb. Them little filters can swell shut & clog for
    not good reason even when new. If that ain't it maybe a clogged
    jet or sticky diaphram?
    Last edited: Feb 18, 2012
  17. rawly old

    rawly old Member

    Geez, I don't know what to tell ya then. sorry, realized 4 stroke and deleted,
    not in time tho. Who'd ya buy it from; got a warranty?
  18. darwin

    darwin Well-Known Member

    When you press the primer bulb does it clear all the air out of the fuel lines and pump fuel through the return line? You should see hear feel it doing so. Could be your diaphram popped, only takes a lil slit to render it useless.
  19. Oban

    Oban New Member

    The primer bulb fills up with fuel and pumps it via the return line.
    There is good flow through the main filter, I checked it before stripping the carb.
    The only reason I stripped the carb is that when the engine stopped it was far too sudden to be a blocking filter so I thought that it might have been an instaneous blockage of one of the jets - but they were all totally clear.
    Something doesn't add up and I don't know if I'm missing something glaringly obvious.
    It's going for a second opinion soon.

    It was bought from Staton as part of a kit with their gearbox and crankshaft kit. It was cheaper and less hassle to do that than buy one here in Scotland.
    I've no doubt it does have a warranty in America but it just isn't worth the cost or hassle of sending it back over.
  20. Your warrentee is not with the company you purchased the engine from(Staton), but with the manufacturer, Subaru-Robin. Check with Robin UK, or whatever the UK importer is called and see if they won't honor the warantee. I know Robin-America would honor the warantee, regardless of where the engine is used, if only for the good will of the name and because Subaru in Japan would want them to. Shipping costs would be high, of course, so it might be cheaper to have a local shop familiar with Walbro carbs and Robin engines check it out first. If you can find your local Subaru Robin dealer, check and see if they won't honor the warantee. I'm fairly certain they will, regardless of where it was purchased.