2-Stroke Cutting out mid trip!

najsmith

najsmith

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Hello Forumite's

My 5yo 2-Stroke Mariner 3.3 has developed a strange trick in my recent motor out to the boat. The engine goes along fine at good speed and then starts to sound like it's struggling, revs slowly decay and then it dies. Choke makes no difference, and when I pull the chord again she springs into life with expected revs and afer a few minutes they start to decay and she dies again.

Is this likely a symptom of overheating? Old 2-Stroke mix?

Good job the engine restarted promptly as the 20knot winds were, as ever, coming from teh wrong direction!!
 
I always change the 2 stroke mix every year, I believe it does not last. Your problem though sounds like fuel starvation, I experienced the same on my 3.3 this year and must check it out. I'm expecting to find crud in the fuel lines or a sticky float jet.
 
I'd suspect a fuel flow problem.

Tank vent as mentioned.

Check fuel flow from tank to carb ... there is a filter in the tap assembly which may be blocked.

If the fuel is not fresh tip it out flush out the tank and replace with fresh.
It can be kept from one year to the next if stored properly but that does not include a part filled tank!

Always worth trying a new plug. So often it seems to cure a problem not obviously plug related!

Regarding overheating. You should be able to touch and maintain finger contact with the cylinder block or head briefly. If you cannot overheating may be your problem.
 
2 stroke probs

We experienced this on an older Mariner 2hp

In our case it proved to be over heating due to impeller damage, ie no cooling water.

Check that cooling water flowing - i.e is being ejected

Check for overheating, in our case the paint blistered on the cylinder head before we realised what it was.

Joe Hull
 
Had exectly this pronblem with a NEW o/b some time ago. Turns out that the breather had not been fully drilled through. 2 secs with a drill bit had it sorted (after hours of wondering what the problem was).

As others have said, check the breather has not got bunged up.
 
Just out of interest, we had a blocked cooling incident on a 3.5 tohatsu (same engine). Steam issued from most places and the nylon(?) steering bushes melted. These engines seem to like having their telltales cleared from time to time regardless of whether they are flushed after use. Whilst you have the covers off to access the fuel tap filter, I suggest you try blowing up the telltale. The tube can be pulled off the spigot and a watchmakers screwdriver used to scrape out the hole. Last time I did this it doubled the amount emitted.

Rob.
 
najsmith said:
Hello Forumite's

My 5yo 2-Stroke Mariner 3.3 has developed a strange trick in my recent motor out to the boat. The engine goes along fine at good speed and then starts to sound like it's struggling, revs slowly decay and then it dies. Choke makes no difference, and when I pull the chord again she springs into life with expected revs and afer a few minutes they start to decay and she dies again.

Is this likely a symptom of overheating? Old 2-Stroke mix?

Good job the engine restarted promptly as the 20knot winds were, as ever, coming from teh wrong direction!!
Click to expand...
Join the club - it's a jamming needle float valve - mine's doing it because of salt crystals in the 2-stroke mixture collected in a couple of trips across Spinalonga lagoon in a F6.
 
rob2 said:
Just out of interest, we had a blocked cooling incident on a 3.5 tohatsu (same engine). Steam issued from most places and the nylon(?) steering bushes melted. These engines seem to like having their telltales cleared from time to time regardless of whether they are flushed after use. Whilst you have the covers off to access the fuel tap filter, I suggest you try blowing up the telltale. The tube can be pulled off the spigot and a watchmakers screwdriver used to scrape out the hole. Last time I did this it doubled the amount emitted.

Rob.
Click to expand...

However the tell tale is just that I think, an indicator that the water is flowing. The vast bulk of the the cooling water goes down the leg on these I believe. Open to correction as always.
 
My experiences with a 3.3 Mariner mirror your own. The motor was kept permanently on the transom, with varying amounts of fuel. It would start well, and run just fine. Then it would fade away. It would usually restart.

I eventually tracked it down to water in the fuel. If you undo the tiny screw under the float chamber and drain it into a glass or something you can see through then you will observe globules of water at the bottom. If I'm right, that is.

If water is present, then you must drain your fuel tank and refill with a fresh batch, and drain the float chamber again. I understand that condensation forms in a tank where the breather isn't closed and the tank isn't full.

Good luck
 
I have a similar, intermittent issue.

Sometimes starts first pull and runs well.

Other times seems little tired, does not pickup revs when throttle opened, and seems as it it is about to die.

Sometimes a little choke helps when feeling poorly.

Seems to be fuel starvation, but I have stripped and cleaned carb loads of times. So now I either suspect a float bowl height issue, or a fuel pipe/tap/filter issue.

(Yes I have changed the plug).

As mine is intermittent, I think it is fuel as otherwise it runs great.
 
yellowspinnaker said:
My experiences with a 3.3 Mariner mirror your own. The motor was kept permanently on the transom, with varying amounts of fuel. It would start well, and run just fine. Then it would fade away. It would usually restart.

I eventually tracked it down to water in the fuel. If you undo the tiny screw under the float chamber and drain it into a glass or something you can see through then you will observe globules of water at the bottom. If I'm right, that is.

If water is present, then you must drain your fuel tank and refill with a fresh batch, and drain the float chamber again. I understand that condensation forms in a tank where the breather isn't closed and the tank isn't full.

Good luck
Click to expand...

+1
My fuel starvation problems were caused by a faulty fuel tap, bypassing that solved the problem.
 
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