Mariner 15hp 2 stroke fuel issues

gocherhaz · 14 July 2017, 17:10

Hello. I have been out today, all was fine for 5 minutes until engine cut out. I haven't had it running properly since. It will start for a very small amount of time may 2 seconds but I think that is just on the primer fuel. I held the fuel take above the carburettor and this seemed to allow it run for a longer time around 10 seconds but once applying throttle it cuts out.
Can anyone help me to solve this it's frying my mind?

Thank you

Fenlander · 14 July 2017, 17:43

''I have the knob set to "Fast Start" and pulled out''

So the OB is looking for more fuel.

First I'd check the supply right from the tank pickup (the pipe into the fuel can come loose on the OE Mariner 25l tanks), the pickup strainer, through the bulb to the carb.

Make sure the filter is clear and none of the under hood fuel pipes is kinked..

Then you are looking at a jet blockage, sticking float, fuel pump issue etc.

As you have tried a gravity feed direct to carb can help diagnose but only if you have proved a good fuel flow from the existing tank if you are using that.

Did you sort the primer spring?

Bigplumbs · 14 July 2017, 17:55

I had a similar thing on t engines drove me mad.

It ended up being the gasket seal between the float chamber and the carb body that was very flat and was letting air in.

Very cheap to replace. Have you had the carb to pieces lately

Dennis

Fenlander · 14 July 2017, 18:40

Good call Dennis... a bad air leak could cause similar... I thought I remembered he'd put a new carb gasket overhaul kit on but that might be someone else.

gocherhaz · 14 July 2017, 19:04

I have tried every pre fuel pump. Yes the spring was sorted in the end the primer side of things is good it's just not pulling fuel. The fuel filter is full and I have cleaned it out.

Bigplumbs · 14 July 2017, 20:34

Quote:

Originally Posted by gocherhaz

I have tried every pre fuel pump. Yes the spring was sorted in the end the primer side of things is good it's just not pulling fuel. The fuel filter is full and I have cleaned it out.

I suspect you have air getting in somewhere

gocherhaz · 14 July 2017, 21:31

Now where it says "TOP" on the carb should there be a small gab that allows fuel out?

Bigplumbs · 14 July 2017, 22:14

Quote:

Originally Posted by gocherhaz

Now where it says "TOP" on the carb should there be a small gab that allows fuel out?

Yes that is the overflow. If you squeeze the bulb too hard it will force past the float needle and out that overflow.

You need to trace all the way from the tank seeing if you have air getting in having first checked the dip pipe in the tank is ok

I in effect have the same engine and have recently done what you are now doing.

I assume you are certain it is fuel and not electrical

Dennis

gocherhaz · 14 July 2017, 22:16

Not 100% sure it's electrical I have a spark on both plugs.

spartacus · 15 July 2017, 10:37

With all fuel related issues, assuming it's fuel then start with the basics. If the outboard has a fuel filter reservoir then check and clean. Additionally check the fuel connection from the fuel tank to the outboard. Non genuine connections are prone to issues such as dislodged 'o' rings. If the fuel primer bulb is hard to prime (rubber hard) then look to replace with genuine Mariner or Quicksilver part. They do deteriorate and the diaphragm restricts flow. Ensure the tank is adequately vented.

If you've checked that - move onto the fuel pump. Rebuild kits are relatively inexpensive. You can split the pump for inspection but I'd want a kit in case you tear anything. You can test, but as engine isn't even running, it's as well to replace.

Finally the carbs. On the bottom of each carb there should be a hex crosshead screw. Remove and drain fuel into a container. Should be uber clean. Any contaminants and you're looking to strip carbs down.

gocherhaz · 16 July 2017, 21:40

Just want to thank everyone for the help.

Still scratching my head on this. I have stripped the carb down again and cleaned it has had new gaskets on it last week. Checked the jet. Still will not go. Fuel line all seems fine. I have a spark on both plugs. I have changed the plugs also.
Just to add to what I said. I was out in the boat and was all running really well then something changed and now will not go.

Yabadabadoo · 16 July 2017, 22:15

Old fuel?

Bigplumbs · 17 July 2017, 05:18

I still think you are getting air in. Have you checked the fuel tank and the fuel line including the bulb. Also disconnect the fuel line the carb side of the fuel pump and pull the engine over with the ignition off to see if the pump pumps fuel out of the end of the fuel line

Dennis

Fenlander · 17 July 2017, 07:07

Sorry to seem flippant but what do you mean the fuel line seems fine? Have you actually proved it is getting fuel to the pump/carb inlet?

You can diagnose this no-start issue in several different ways but personally I'd rig up some sort of temp fuel supply with perhaps an old gear oil container held upside down with a hose to the carb so it's gravity fed. Another way to test similar is to put some fuel mix in a trigger spray (household cleaner type thing) and spray in the carb throat while pulling over.

If it fires with the fuel spray down the carb throat then you have proved the spark and that the engine will run so can look more into fuel line, pump & carb.

If you use the gravity container and it starts/runs you've also proved the carb.

Bigplumbs · 17 July 2017, 07:29

Also next to the main jet there is a little bung which you remove and underneath is the idle jet that you can also remove to clean out. Did you do this

Regards

Dennis

Yabadabadoo · 17 July 2017, 07:35

From memory on another thread a few years back there’s also a little primer button (plastic blue?) near the carb that can get gunked up and stuck

Fenlander · 17 July 2017, 09:08

Gocherhaz do you have this fuel tank?

gocherhaz · 17 July 2017, 09:15

Quote:

Originally Posted by Fenlander

Gocherhaz do you have this fuel tank?

Hi Fenlander. No I don't

Fenlander · 17 July 2017, 09:38

OK... not saying it can't happen with others but the tank like mine is where the pickup pipe can come loose on the connector block so pulling in air... even falling right off to the bottom of the tank.

gocherhaz · 17 July 2017, 09:53

Quote:

Originally Posted by Fenlander

OK... not saying it can't happen with others but the tank like mine is where the pickup pipe can come loose on the connector block so pulling in air... even falling right off to the bottom of the tank.

I will check this tonight. Thank you