Any mariner experts here ?

[Kiss my bass]

Hi,
This is my first post as just registered due to looking for answers on the net, and this site came across as one that may be able to shed some light on my problems.

I run a 1999 mariner 2 stroke, ex rnli engine, a few weeks ago, about 2 miles offshore on a trip out it went wonky, I mean, it died, started instantly on the first pull, but would not rev up properly without spluttering and dying, I ran back in on very low revs and it seemed fine, would idle perfect, just not rev up under load.

Into the mechanics it went, he stripped the carbs, found minute parts of muck and small droplets of water, but next to nothing by all accounts, cleaned them up, changed plugs, leads and caps as reckoned I had a weak spark, everything seemed normal so he tested it in water and the engine ran perfect, returned the boat, I went out yesterday, exactly the same problem, about 2 miles out again ! Yet it ran perfect until that point, did not miss a beat, getting back was another story though........ It ran like a bag of sh##e, and got worse the longer it ran, until I was virtually on idle, yet drop it out of gear and it idled perfect, so guys, any suggestions, so far I am thinking, carbs got muck in, stator, timing, possibly engine temp sensor gone wonky and giving the wrong signals to the timing ?.

I am no expert on outboards, but trying to learn so I can fix things myself if that makes sense.

Thanks in advance for any help you may be able to share.

Robert.

[Downhilldai]

Check fuel system first. It could be drawing air into the fuel line if there's a dodgy connection, or the fuel pump may be defective. Did you try pumping the fuel primer bulb to see if it made any difference?

I'm assuming your tank vent was open?

[Kiss my bass]

Originally Posted by Downhilldai

Check fuel system first. It could be drawing air into the fuel line if there's a dodgy connection, or the fuel pump may be defective. Did you try pumping the fuel primer bulb to see if it made any difference?

I'm assuming your tank vent was open?

Hi, thanks, yes I tried it on two different tanks and lines, I also tried pumping the primer bulb, but it was hard and made no difference at all, yes the vent was open.

[jambo]

Originally Posted by Downhilldai

Check fuel system first. It could be drawing air into the fuel line if there's a dodgy connection, or the fuel pump may be defective. Did you try pumping the fuel primer bulb to see if it made any difference?

I'm assuming your tank vent was open?

Got to agree with DHD. As you can see I have a Mariner the same happened to me 2 years ago would not go above 2000 revs but sounded okay. it was the diaphram. Try it I think that could be the culprit, surprised your mechanic did not test for it.
Hope you get it sorted.

[Kiss my bass]

Originally Posted by jambo

Got to agree with DHD. As you can see I have a Mariner the same happened to me 2 years ago would not go above 2000 revs but sounded okay. it was the diaphram. Try it I think that could be the culprit, surprised your mechanic did not test for it.
Hope you get it sorted.

I will have a look at that next time I go to the boat, thank you, I was surprised to hear he did not test the engine under load as it was on a trailer not ten metres from the slip and I explained it was only problematic under load when it went in to him. He is also a mariner mechanic. Mine does not sound ok at all, unless it is on idle or from cold, when warm under load it sounds like it is missing.

[Festinghouse]

i had this twice with my old merc 25 - both times it was the cdi unit. before spending any money on parts get a multi meter, then search the net for the correct tests to carry out on the cdi, the stator and the trigger. you may however need to run your engine until the fault occurs before running the tests .Boatinfo - boat brochures and manuals for boats and marine engines! this has been a useful site for me.

[Kiss my bass]

Originally Posted by Festinghouse

i had this twice with my old merc 25 - both times it was the cdi unit. before spending any money on parts get a multi meter, then search the net for the correct tests to carry out on the cdi, the stator and the trigger. you may however need to run your engine until the fault occurs before running the tests .Boatinfo - boat brochures and manuals for boats and marine engines! this has been a useful site for me.

Thanks, I have spoken to black dog marine and they kindly emailed me all the test procedures to go through for the stator, coil, etc, I have a meter so that's possible to do, just wanted to get an idea on what I should be looking at first, it sounds like I need to be spending a day or two going right through everything until I find the issues.

[uncle al]

is it an early rnli obm? if it is it may have been missed when the water trap filter was changed , they were modifid to stop dirt dropping into the clean fuel side of the filter.the stator should be a red one if not i would change itcheck your spark plugs are they the same colour?

[Budgie1]

My stator just stopped working when engine was running and didn't fire again until it was replaced so not convince it is the problem, the earlier ones where troublesome and the later (red) ones far more robust. Wouldn't change one until sure I was quoted £500 plus for new on my Merc 60hp, bought Mariner 60hp doner engine used stator off also changed gearbox and a few other bit but still have many parts if of interest to anyone

[jezza2011]

My stator did exactly what your engine is doing.
ran fine untill it was under load.
then would not do more than 2000rpm without dieing.
ok at idle in gear.

[Kiss my bass]

Originally Posted by uncle al

is it an early rnli obm? if it is it may have been missed when the water trap filter was changed , they were modifid to stop dirt dropping into the clean fuel side of the filter.the stator should be a red one if not i would change itcheck your spark plugs are they the same colour?

Not sure if it is early or not, all I know is the year is 1999.

Stator, also not sure if it is red or not yet as I have not even lifted the hood as yet, I should know this weekend as I am returning armed with tools and information to check it all out, I have been quoted £182 for a new stator, so not as scary as some prices I have heard.

It has just had a new set of plugs, but I will change them anyway, if that's not the problem at least I will have a spare set on board

[Kiss my bass]

Guys, just wanted to say thanks for all the input, mixed opinions on the problem, and most of you have come up with the items I had under suspicion. You have all been very helpful, thank you.

Feel free to keep the suggestions coming, I am going to strip it on Saturday/Sunday, so good to know what I need to look at and what to take with me.

Robert.

[uncle al]

Just as a thought there was a problem with the earths on the earlier obms, that were supplied to the R.N.L.I. we then as a part of the build all earths were dis-connected checked, cleaned to bright metal and refitted then sealed with liquid neoprene