DF40 won't start after warm

[Raberko]

I have a DF40 outboard (year 2000) it starts fine the first start of the day. I will run it for an hour and then stop and fish for 30 minutes and then the motor will not start. It turns over but does not start. I can get it to start if I pull up the throttle lever all the way and turn the key. When it does start, there is some white smoke. It is not a consistent problem and as such I am losing confidence in the motor because I do not know if it will start or not.

[Moonlighter]

Have you checked the primer bulb when it does this? Is it sucked flat?

Checked the tank breather to make sure it is open?

Fuel lines not pinched anywhere?

When was the last time you checked and changed the fuel filters, especially the inline filter between the tank and the engine?

It doesnt sound like a serious problem, will be something simple. Has a mechanic had a look at it and checked for any fault codes?

[Raberko]

The primer bulb is soft. The tank breather is open. Fuel lines are not pinched. I have not checked and changed fuel filters recently, I will check into that. Mechanic did check and found no fault codes.

[ChrigelKarrer]

When it does start, there is some white smoke.

White smoke don't exist on outboards,
if it is white, it's steam
if it's blue/black it's oil or too rich gasoline fumes and then it's smoke

Steam from a engine is not a good sign, there may be some steam coming from the propeller, but normally is no steam from the exhaust above the water.

If it is steam, the engine may overheat and the steam is water evaporating in the cooling passages when you crank the engine after a (short) period of engine stopped.

After running the engine hard you should have her ideling for some minutes to let her cool down as the cooling water flow will stop when you switch the engine off and the temperature inside the engine will rise fast and strong.

Chris

[redlowrey]

When it doe's start is it missing or doe's it run fine. Pull the plugs out and look and see what colour the tips are, black, sooty white rusty.

[redlowrey]

White smoke don't exist on outboards,
if it is white, it's steam
if it's blue/black it's oil or too rich gasoline fumes and then it's smoke

Steam from a engine is not a good sign, there may be some steam coming from the propeller, but normally is no steam from the exhaust above the water.

If it is steam, the engine may overheat and the steam is water evaporating in the cooling passages when you crank the engine after a (short) period of engine stopped.

After running the engine hard you should have her ideling for some minutes to let her cool down as the cooling water flow will stop when you switch the engine off and the temperature inside the engine will rise fast and strong.

Chris

MATE I don't want to rain on your parade, but with individual injectors if one sticks open the smoke will be white.

[Raberko]

When it starts, it runs just fine. I will check the plug tips and let you know. From what I recall, I think they were black. I will double check.

[catacom225]

Df 40

Raberko, It could be flooding, If you're only getting a puff of smoke Its sometimes difficult to distinguish between white and blue. Let it run on the muff at home,then wait 30 min and check if the pluges are wet

[redlowrey]

If you know how to use a digital multimeter, disconnect the temp sensor on the cyl head and measure the resistance in ohms and take note. Connect it back up and run the engine till it gets hot, stop the engine and disconnect the sensor and check the resistance again taking note. What I think is happening the ecu is injecting fuel on a cold start, high sensor resistance high signal voltage around three volts and as the engine heats up the sensor resistance should start dropping and the signal voltage dropping too. The tell tale sign is you have to lift the warm up leaver and get more air into the cyl.