Mariner 15 2s problems

[lew198]

Hi all,
so I got out on the water today to test my newly purchased old mariner 15 2s (1986) and was going lovely for all of 2 minutes until problems struck.
It kept dying like it was being starved of fuel, I reprimed each time as the primer became very soft, could this be a failing fuel pump? It would then be hard to start taking about 10 pulls, unusual as it starts second pull when cold. Then it would only run at high revs and wouldn’t idle. Even if I came off the revs slightly it would bog and die.
Then to add the cherry on top the spring went in the pull starter, so I got a nice little work out rowing back to shore.
Here’s my plan of action;
New spark plugs
Clean carb
Test/replace fuel pump. (Anyone know if they can be tested?)
New fuel filter

If I’m missing something or you have any suggestions please let me know!
Thank you,
Lewis.

[neil.mccrirrick]

Was the vent open in the fuel tank? First place to consider as it sounds like lack of fuel

[lew198]

Originally Posted by neil.mccrirrick

Was the vent open in the fuel tank? First place to consider as it sounds like lack of fuel

Yes the vent was fully open

[Oldman2]

I would change the fuel hose and primer from the tank, hose isn't silver by chance is it? They collapse internally so nothing to see outside but really restricts fuel flow.

[lew198]

Originally Posted by Oldman2

I would change the fuel hose and primer from the tank, hose isn't silver by chance is it? They collapse internally so nothing to see outside but really restricts fuel flow.

Nope it’s a black hose with a Honda primer that came with a Honda tank, although I have changed the tank to a plastimo and took the pickup from the Honda and transferred it to the plastimo. It looked fine and primed fine but I will give this a closer inspection

[lew198]

I did just discover this pipe disconnected (39), although i first assumed it was just a breather, seeing the diagram I found there’s a nub on the left of the carb that looks like the pipe should be connected to, so I put it on.
Any ideas what this pipe does and what affects it has on the carb?

[neil.mccrirrick]

Was the fuel filter full of fuel? If yes the fuel pump has pulled fuel. If no dodgy fuel line or primer as old man says.

If it was full likely dirt in the carb , could still be fuel pump bit more likely carb.

Was the carb primer knob pushed back in?

If you run it again and when it stalls pulling the primer knob gets it running again probably main jet blocked.

[lew198]

Originally Posted by neil.mccrirrick

Was the fuel filter full of fuel? If yes the fuel pump has pulled fuel. If no dodgy fuel line or primer as old man says.

If it was full likely dirt in the carb , could still be fuel pump bit more likely carb.

Was the carb primer knob pushed back in?

If you run it again and when it stalls pulling the primer knob gets it running again probably main jet blocked.

Thanks for that Neil.
I did not check the fuel filter, but I was manually priming the bulb after experiencing problems (thinking it may be the pump playing up) but it had no noticeable effect.
Do you mean the choke knob? If so choke was off, it didn’t want to start with any choke either.

[Tommy c]

https://www.ebay.co.uk/itm/325705357...temCondition=4
The pics in this listing show your pipe connected only one end

[lew198]

Originally Posted by Tommy c

https://www.ebay.co.uk/itm/325705357...temCondition=4
The pics in this listing show your pipe connected only one end

Thank you for that!
This is the nub I connected it to. I will get the carb off tomorrow for a strip and clean and see if I can work out what this pipe is for!

[Trello]

I don't know this engine, so this is a guess - but it could be an impulse line from the crankcase to power a diaphragm fuel pump in the carb. That would also make sense with the symptoms you're getting - it might have popped off after the first two minutes, starving your engine of fuel.

If that is the case, then the pipe will fit onto an opening into the crankcase.

But as I say, I'm really guessing here - I'm much more acquainted with terrestrial engines. But the principles should be the same...

[smallribber]

Carb gasket could be sucking air. Replace the gasket on the float assembly

[Max...]

I have a later Mariner 15 but your description is close to what I had and this was the culprit:

https://www.rib.net/forum/f36/reachi...tml#post631280

[lew198]

Thanks for the info guys I will check those things out

[neil.mccrirrick]

I’ve a later model of this engine so the carb is a little different and without seeing your manifold this may be incorrect

On the later model the hose connects to the manifold and provides crankcase pressure. It’s under the carb when it’s on so hard to see

[lew198]

Content of the fuel bowl, looks like sand but it crushes into a powder. Granted I normally work on bikes but I have never seen so much contaminants inside a carb! In my best American accent “well there’s your problem”

[Nos4r2]

If the fuel primer bulb is soft the fuel pump is usually your problem.
You may have uncovered a carb problem as well with all that crap in there, but my immediate goto would be new fuel pump diaphragm and gaskets.

[lew198]

Originally Posted by Nos4r2

If the fuel primer bulb is soft the fuel pump is usually your problem.
You may have uncovered a carb problem as well with all that crap in there, but my immediate goto would be new fuel pump diaphragm and gaskets.

It turns out the fuel filter and float bowl was full, can’t remember if I was hand priming right at the end so I will do some bench tests and observe the lever of fuel in the filter. I just stripped the fuel pump and it all seemed good! Diaphragm had no pin holes or tears. Right now I’m thinking it was clogged jets, there was honestly so much crap in the carb and around the jets I’m shocked it ran at all!

[smallribber]

Originally Posted by lew198

It turns out the fuel filter and float bowl was full, can’t remember if I was hand priming right at the end so I will do some bench tests and observe the lever of fuel in the filter. I just stripped the fuel pump and it all seemed good! Diaphragm had no pin holes or tears. Right now I’m thinking it was clogged jets, there was honestly so much crap in the carb and around the jets I’m shocked it ran at all!

Looks like you have found the issue. As many have said perhaps replace the fuel line because they do break down and they are cheap enough

[lew198]

Originally Posted by Easedalenovice

Looks like you have found the issue. As many have said perhaps replace the fuel line because they do break down and they are cheap enough

Will do thank you!