Mariner 10hp OB Starting Problems

Lilbarwell · 29 July 2016, 18:00

Evening all, I'm new here so be kind and bear with me

I'm new to the whole SIB / RIB scene but am so far absolutely loving it! I've always tinkered with cars and motorbike but boat engines are a novalty and I'm stuck....

I acquired a 2006 mariner 10 Hp, short shaft relatively cheap. I bought it as a project, since it didn't run - I was told it had no spark and needed a new CDI unit. Having got it home it appears to have a spark on both plugs so I thought I'd strip down and clean the carb (I thought perhaps a fueling issue).

Unfortunately with freshly cleaned carbs and what appears to be a reasonable spark, it still doesn't run; not so much as a splutter!

My question for the forum is, any ideas? What can I check next and how can I trouble shoot and eliminate various aspects of the carb or CDI.

Many thanks. Richard

jeffstevens763@g · 29 July 2016, 19:13

Put some fuel in each cylinder put plugs back in and leads on try and start you might have a spark but may not be hot enough to ignight the fuel

Fenlander · 29 July 2016, 19:25

Another avenue... if you pull the plugs after trying to start (before trying Jeff's tip) are they bone dry or wet with fuel... that will give you a big clue.

slate1234 · 29 July 2016, 19:30

why not start with a compression test and go from there,

jeffstevens763@g · 29 July 2016, 19:47

Quick compression test put your thum over each hole if it blows it off chances it's ok.
Are they new plugs?
Has it been for a swim signs of corrosion under the hood white deposits everywhere

Lilbarwell · 29 July 2016, 19:47

Thanks for your super quick responses, much appreciated! The plugs didnt seem bone dry but I had been tinkering with a little easy start...should have paid more attention!

I did throw some fuel down each cylinder and nothing too exciting happened. I wasn't sure if I put too much down the hatch but you could be right about a weak spark.

What would diagnose the reason for a weak spark?

I guess I'd need to take to OB to a marine mechanic to do a compression test. What would that show? Can't say I've ever had one on any engine, always got there myself... Eventually!

Massive thanks for your help

Lilbarwell · 29 July 2016, 19:54

I'll give the 'compression test' a go!

It all looks in pretty decent shape, although has been messed with a little. I'm told it's a 2006 model but appears to me like bit of a cut and shut. Pretty rough shape if it is a 2006.

No masses of corrosion or crud under the hood and carb looked in good shape! Looking into the engine the inlets looked a little rough which was why I thought it might not be the original block.

jeffstevens763@g · 29 July 2016, 19:54

If the spark was good it would fire up after a few pulls you say you were told it needed a new CDI unit chances someone has done the ground work but not bothered lack of funds maybe.if you have low compression possibly kn--ked engine one made up of bits.

Lilbarwell · 29 July 2016, 20:09

is there anyway I can check engine number against the number shown on the leg - ultimately would be good to know for sure where I stand.

I actually own another couple of Mariners a 6hp which runs great and a 7.5hp which is in bits. I was hoping to make this 10hp a runner with the parts available. The 10hp is exactly what I want (hopefully), powerful enough for my SIB, fairly recent and short shaft. I'd been 'making do' with a long shaft on my Honwave.... I know, I know, but hey I'm on a buget and having some great fun!!

psycho · 29 July 2016, 20:17

Just a thought, could it be a duff kill switch? As there are 2 of them on that model. One where the cord attaches, and a push button one on the end of the tiller

Lilbarwell · 29 July 2016, 20:18

Quote:

Originally Posted by Fenlander

Another avenue... if you pull the plugs after trying to start (before trying Jeff's tip) are they bone dry or wet with fuel... that will give you a big clue.

If the plugs are wet with fuel but the plugs appear to be sparking, what's the next step? Thanks!

jeffstevens763@g · 29 July 2016, 20:23

I would do a compression test and a cost analysis on a new CDI unit and any other stuff suspect then have a think is it worth it if it has been messed with it could be a can of worms. Or use your 6 hp your on the water then and have it as a strip down project not spending till you know if it's worth it you have the skills what can you lose.

Cheer.s

Lilbarwell · 29 July 2016, 20:25

The engine had been set up for controls so only had 1 kill switch - definitely not this since it does spark. I guess I need to establish whether the spark is strong enough.

Fenlander · 29 July 2016, 20:27

>>>If the plugs are wet with fuel but the plugs appear to be sparking, what's the next step?

Two things... is there *too* much fuel... flooding? Or is the spark at the correct time... timing... usually never altered but you have doubts about its history.

Oh and trying a new pair of plugs wouldn't be a bad idea.

Lilbarwell · 29 July 2016, 20:29

Thanks for your help Jeff really is much appreciated. I've just been out to have a look and compression seems strong so far as I can tell (thumb over the hole).

I tried putting the CDI from my runner on earlier but couldn't get a spark at all. Was planning on trying the CDI from the 7.5 but that's in Bristol and I'm in Cornwal. Don't suppose you know whether they are cross compatible, i suspect not although if it's just the ignition system for 2 cylinders i don't know why it wouldn't be the same

Lilbarwell · 29 July 2016, 20:32

I don't know much about its history but the guy seemed really genuine (I know they all do) and I think he said it just stopped running. I'll drop him a message because he was really helpful.

The plugs certainly aren't dripping wet with fuel , so I doubt flooding.

Fenlander · 29 July 2016, 20:51

>>> plugs are wet with fuel but the plugs appear to be sparking

Another thought if the spark is present but not brilliant when tested with the plug/s out then under compression the spark may be insufficient to ignite the fuel.

Also are you trying to start with or without choke... and forgive me for asking but do you understand the relationship between raising the idle ( a timing change) priming squirts of fuel with the choke knob via the plunger it operates and then having the choke itself in or out?

Lilbarwell · 29 July 2016, 21:07

What would cause the spark to be weak under compression; solution perhaps new plugs and leads?

I've tried a little bit of everything, choke no choke, primer and easy start. I'm not exactly sure what you mean, as I said I'm pretty new to these engines. I stripped the carb and it all looked good. What I couldn't understand was how the needle distributes the fuel into the carb. There doesn't appear to be any holes in the needle as a conventional motorbike carb had.

I would have thought the engines are relatively simple, Is it just the costs of parts that makes people not bother repairing them?

paddlers · 29 July 2016, 21:24

Without you've got all the test gear that's appropriate for these things I've found diagnosis more like guesswork. Last year my 135 developed a starting & top end intermittent fault. Did all the usual stuff cleaning carbs,new plugs. All sparking, plenty of fuel etc Took it up to Clyde Outboards turned out to need a new switch pack (£160) it has two. Had the carbs stripped and ultrasonically cleaned.
Now runs like a sewing machine !!
The point I'm trying to get across is sometimes it pays to get a professional in if all the obvious stuff comes up blank. A decent marine mechanic is worth every penny but they're not always the least expensive or the easiest to find.

neil.mccrirrick · 29 July 2016, 21:38

When I had motorbikes that wouldn't start and I was struggling to narrow things down I followed all the advice above ie is there a spark are the plugs wet. If they are take the plugs out and put them in the oven. Get them hot. Wear gloves and put back in the cylinder and try to start. If it doesn't start then it's usually the timing that is shot