Suzuki DT 6 stops like when running out of fuel

[Bob666]

Hi!

We got a Suzuki DT 6, 2-stroke, 2 cylinder outboard engine for our dinghy. Just bought it, no manuals.

If I keep pumping fuel the engine runs on, otherwise it stops after a while, much like when you run out if fuel.

I have replaced fuel tank, fuel, put double hose clamps in many places, fuel filter, membranes and spark plugs.

Still same issue.

Fuel hose about one meter.

Any ideas, anybody?!

Suspecting carburator:
http://www.marineengine.com/boat-for.../t-393291.html

Pics and movies:
https://drive.google.com/open?id=0By...WF6Zkp0SFl1LVk

I filmed two things as I don't know their function. The knob in the lever, what's it for, please?

The button I pull under the engine, why can it be moved?

Cheers

[petter5]

Originally Posted by Bob666

Hi!

We got a Suzuki DT 6, 2-stroke, 2 cylinder outboard engine for our dinghy. Just bought it, no manuals.

If I keep pumping fuel the engine runs on, otherwise it stops after a while, much like when you run out if fuel.

I have replaced fuel tank, fuel, put double hose clamps in many places, fuel filter, membranes and spark plugs.

Still same issue.

Fuel hose about one meter.

Any ideas, anybody?!

Suspecting carburator:
1995 DT6 longshaft runs only with choke, not well, will not idle. [Archive] - Boat Repair Forum

Pics and movies:
https://drive.google.com/open?id=0By...WF6Zkp0SFl1LVk

I filmed two things as I don't know their function. The knob in the lever, what's it for, please?

The button I pull under the engine, why can it be moved?

Cheers

Maybe lower crankshaft seal failure resulting in reduced crankshaft housing vacuum pulse in the crankshaft housing witch is required for proper operation of the fuel pump.

[Bob666]

Hi!

Close to bringing it to a mechanic. Tried starting it again this morning:
https://drive.google.com/open?id=0By...Gd1N29oMk9mMVk


Replacing the crankshaft seal sounds easier than mending the carburator.

However, one should first determine the root cause. It has not yet been established.

Cheers

[a64pilot]

If it runs when you pump the bulb, but quits soon after, almost certain that is the fuel pump, it works off of pressure pulses in the crankcase causing a diaphragm to flex and pump fuel.
Almost all of the time a pump fails it's the diaphragm has ruptured or I guess a check valve stuck. Personally it's always been a diaphragm.
It's not a hard fix. I've met very few people that thought to try the squeeze bulb without being told to, good thinking.


Sent from my iPad Pro using Cruisers Sailing Forum

[Bob666]

Originally Posted by a64pilot

If it runs when you pump the bulb, but quits soon after, almost certain that is the fuel pump, it works off of pressure pulses in the crankcase causing a diaphragm to flex and pump fuel.
Almost all of the time a pump fails it's the diaphragm has ruptured or I guess a check valve stuck. Personally it's always been a diaphragm.
It's not a hard fix. I've met very few people that thought to try the squeeze bulb without being told to, good thinking.

Thanks, I though so in the first place, so I did replace the diaphragm. Could I have mounted it incorrectly? It seems it can only be mounted one way? It was a little tough to make it fit had to pull it a little to make it go on the small pins in the metal everywhere.

Cheers

[Clivevon]

Obvious iknow,but my small outboard has an integral fuel tank and there is an air valve in the top of the filler cap to let air into the tank as the fuel is used. If that valve was left closed, no air would get in and a vacuum would build up in the tank, starving the engine of fuel.
You have a separate tank but I presume the same principle applies? Is there an air valve in the filler cap?

[Manos1955]

Make sure it seals well and there is no air

[reed1v]

At least it runs. Got a vacuum leak somewhere.

[seabreez]

Originally Posted by Bob666

Hi!

We got a Suzuki DT 6, 2-stroke, 2 cylinder outboard engine for our dinghy. Just bought it, no manuals.

If I keep pumping fuel the engine runs on, otherwise it stops after a while, much like when you run out if fuel.

I have replaced fuel tank, fuel, put double hose clamps in many places, fuel filter, membranes and spark plugs.

Still same issue.

Fuel hose about one meter.

Any ideas, anybody?!

Suspecting carburator:
1995 DT6 longshaft runs only with choke, not well, will not idle. [Archive] - Boat Repair Forum

Pics and movies:
https://drive.google.com/open?id=0By...WF6Zkp0SFl1LVk

I filmed two things as I don't know their function. The knob in the lever, what's it for, please?

The button I pull under the engine, why can it be moved?

Cheers

Remove the carburetor. I would drop the fuel bowl and try to see if there is water in the bowl and then check to see if the float and needle are free to move. Then check the high speed jet, (remove it) then check the orifice to see if it is clean and if you see through it. Then reassemble and try it.

[a64pilot]

I'm a little confused, it has an internal fuel tank, and a squeeze bulb?

If you have changed the diaphragm, I'd look next at the check valves, there has to be two of them, if one has stuck, it's not going to pump. Being that it runs and runs well when you squeeze the bulb, it is more than likely a fuel delivery issue, and that sort of leads us to the pump.
It could be float level is too low and the excess fuel pressure is forcing fuel past the needle valve, but I wouldn't bet lunch on that

[Sojurnr]

Had a similar issue decades ago with a 140 Hp inboard/outboard in the summer on Lake Mead, Nevada, USA. After 20 or so minutes of running it would quit and not restart for perhaps 15 minutes. Afterward it would start and run normally for another 10 minutes or so, then repeat the "patience training exercise".

Vapor lock (overly warm fuel under insufficient pressure to prevent vaporization) in the fuel line was the culprit. Later learned it was a known issue with that particular setup and there was an after-market water jacket cooled fuel line which could be purchased on self-manufactured.

But it sounds like your issue is most likely the fuel pump.

JK

[letoile]

I agree with the carb diaphram issues... but the first thing I would check is the new tank. Some of the new EPA tanks do not vent even when the vent is open and creates a vacuum and prevents gas from flowing to the motor. It happened to me with a brand new motor that would not run. I simply loosen the entire cap while using the kicker to get our sailboat in and out of the marina and tighten it when not in use. I also disconnect the hose to the motor when not in use since the tank will not vent and will also build up pressure and flood the motor when the tank gets hot and expands. Simple fix and worked for me.
Boating groups raise concerns about new outboard engine fuel tanks
Good luck!

[Bob666]

Hi!

First of all, I have opened the little air intake knob on the separate fuel tank. I pump up pressure in the fuel bellows until it is stiff.

Why is there no hose on this nipple on the fuel pump?:
https://drive.google.com/open?id=0By...kN4Ukx0OHgwUTQ

I have replaced all hoses internally as well. Except a thin hose from the top of the cylinder to the lower part of the engine:
https://drive.google.com/open?id=0By...lRpVWt5VGRVNE0
https://drive.google.com/open?id=0By...jJJX2wwdjVGWk0

As I didn't have one.

I got the engine to run a few minutes today, only tried in neutral gear. It does not respond well when accelerating the engine, there is a delay. I can run for a few minutes, then the RPM goes down a bit...you know it will soon stop...then it stops and no way you can accelerate it to increase.

The bellows does not stay stiff all the time and sometimes it is like I cannot use it to pump the fuel into the engine, nothing happens and the bellows is soft. Then suddenly it does accept fuel and stiffens.

I used to say "I don't do carburators". Might as well practice on this engine to get better. No harm in removing I suppose.

I opened the fuel pump to verify I had mounted the gaskets and diaphragm correctly. It seems so. I could not see the valves mentioned above? What are those, please?

The plan as it stands now:
Replace the thin hose.
Try again.
Issue persists -> remove carburator and change the gasket between carburator and cylinder and have a look at the carburator according to tip above etc. Will be careful not to adjust any screws or do anything I do not feel confident in.

The vacuum stuff is greek to me.

Perhaps have somebody knowledgeable have a look at the carburator.

I have a lawnmover. Old Briggs and Stratton engine. Simple 4-stroke. I got the splendid idea to make it run better, so I removed the simple carburator, brought it to work where we have ultra-sound cleaning. Ran it there, assembled it again, and the engine hardly started. Had to have a workshop fix it.

Cheers

[Jim-T]

I would remove carb. and check the low speed jet high speed jet and the emulsion tube. most likely cause sounds like high speed jets or the tube. those are the simplest things. your picture comes up small, but it does not look like you have a filter between the pump and carb. With todays fuels I always run one for several reasons. Much of the zink (it a stabilizer) has been remover from the fuel and with alcohol in it causes way to many problems. Drain your fuel at the end every season and start your motor to drain the float bowl otherwise the quickly degrading fuel will cause you nothing but problems.

[Bob666]

Ok thanks. Will delve into the mystic area of carburators then.

Is this the right manual, please:
https://drive.google.com/open?id=0By...WVsT2d3Ylp4aVU

The hoses - am I ok using just one fat plastic cable tie for the connection points? Went to workshop today to purchase the hoses, man there said that's better than double hose clamps. I suppose that's not valid for the big hoses on the Volvo Penta 2003 inboard diesel engine on the sailboat, right? I use double stainless hose clamps there, mounted in opposite directions.

And, by the way, never touch an engine that's running ok, right?! (Except maintenance).

Cheers