250 Outboard cutting out on second run issues

[Mark Harris]

I have a rib with a 250 Four Stroke outboard. It runs fine when at high revs and on its first run but after a stop and restart it only runs for about 6 mins then it splutters to a stop. I have had all fuel lines changed, aux tanks fitted, low pressure fuel pump changed, tried changing ECU still does it. I found some residue in the vapour separator so changed it which cleared the problem, however the problem has come back, any suggestions?

[Hoosmatroos]

Changed your water separation filter?

[Mark Harris]

Changed your water separation filter?

Tried that, that's a part of the annual service, this issue has been going on now for three summers. It even does it using aux tanks feeding straight into the engine from the Lazarette so it is definitely the engine, however thanks for your suggestion.

[Striperk9]

Summer is the keyword here. All my issues also happen only in the hotter months.
Sure sounds like vapor lock to me. Even the Suzuki trained mechanic I talked too brought up the term.
Your 250, another 250 that posted similar issues and mine (DF200 but same block). All seem to run fine until the motor heats up, then the problems start.

[artdf175]

IF this conversation leading to some type of overheating but not enough to set off an alarm..
have you checked / replace the thermostat?
and there maybe two different thermostats for two different temperatures openings.

and also check the high pressure water bypass for debris that may cause this to be stuck in the open/partial open position?
on my 175 .. on the port side is the fresh water rinse hose connection
If your's is the same, I can only suggest inspecting behind that cover plate.
on my engine this is where all the water to cool the head passes through..
I would be looking for debris that might plug or partially plug the free flow of water through this and look for corrosion that may have eaten through the wall allowing cooling water to run back into the exhaust discharge behind the water jacket not allowing full water stream to pass through the head.
Art

[Striperk9]

that would make sense, Art

Art,

That sounds like a very plausible explanation. I will look into this for my problem as well. If the head is getting hot enough to boil the fuel but not hot enough to set off the high temp sensor, I could see the problems in all three scenarios occurring.
Is the DF175 a V6 like the 200-250s? My 200 actually has 2 thermostats. I replaced these last year when I had similar problem to Mark here.
I wonder if my dealer could scope it out for me?

[artdf175]

The DF175 is a straight 4
One thing I see missing in your comments is the water pump
How old is the current impeller?
The other question is the high pressure pump
You say you cleaned it and that worked for a while
Have you gone back in and rechecked ?
What is the condition of the float valve?
Doesn't make sense that it would restart- run several minutes- and then shut down .. sputter to a stop certainly does not sound like a vapor lock- sounds like a fuel starvation issue
How old is your engine and how many hours?
Art