Resolving Vapor Lock Issue-2007 DF200

[Lostsoul58]

Has anyone found a conclusive fix for the notorious vapor lock issue?
I've spent a lot of money on fuel lines, filters, separators, bulbs, additives, & spark plugs and still have the hot soak-loss of RPMs during the summer weather.
Stumped. Pissed off. Embarrassed. Tired. Going broke.
Tank vent fine. Using Valvtect fuel from a Marina that pumps fuel nonstop.
There has to have been something that was found that stopped this madness...

[artdf175]

a little more information
how many hours on the engine/
when did you last check the valve clearances?
condition of old plugs when you took them out
when you changed water/fuel filter -any water at all mixed in ?
condition of inline fuel filter? debris of any kind?
high pressure fuel pump -- cleaned internal fuel filter?

It looks like you have clean fuel.. but to rule your tank and fuel source out, find a 5 gal external tank and plug it in directly to the engine and see if you have same condition..

engines very sensitive to electrical conditions how old are your batteries?
make sure all connections have been taken apart, cleaned. including all grounding wires

Art

[Lostsoul58]

Art
Fuel is clean. All filters have been replaced with no trash or water in the old filters. Spark plugs looked clean. Porcelain still white with no wear at electrodes. Changed them anyway. Have not disassembled VST to clean that filter. Runs darn good except for the hot soak. Even then it's one in ten times. Only happens when there are guests on board. Embarrassing. The batteries were new last summer that remain on a shore line fed conditioner after every trip. All connections are tight and clean.
I'm going to install exhaust header insulating wrap on the fuel lines under the motor cover.
After that I'm at the end of my abilities.
210 hrs on motor.

[artdf175]

one more question "hot soak"
explain .. not familiar with that one!!
describe it a bit more

Art..

[Lostsoul58]

one more question "hot soak"
explain .. not familiar with that one!!
describe it a bit more

Art..

Engine shut down after a long period of "spirited" running. Everything sort of stews/soaks in the heat.

Hot soak may be more of an automotive term I guess.

This problem never occurs 1st half of the day. I'm always pulling anchor and moving to different fishing spots. Towards the end of the day is usually when this shows up...

[artdf175]

thanks.. I did look up the expression
that leads me to the question .. when was the water pump impeller last serviced?
the engines do not normally run hot ..
normal change interval for the impeller is every two years, regardless of hours
the fins start losing their flexibility and are half compressed in the pump housing.. therefore are not pumping a full load of cooling water to the head.
you didn't mention checking the thermostat
and one other check point in the cooling is the pressure relief valve.. this has been known to get some type of debris stuck in it and does not allow the proper water pressure, again to the head.
Art

[Lostsoul58]

I'm sure the impeller as well as thermostat should be changed. I bought the boat Feb 2015 and it hasn't been changed sine I've owned it. The previous owner seemed to get amnesia when discussing the service this boat had prior to the sale.
That will be on the list to do.
So I take it the symptoms are more of an engine cooling issue causing the fuel/vapor issue?

[artdf175]

What you have more or less described is an overheating problem
I would first get the impeller changed since you don't know how old it is
Then try to see if you can duplicate the problem
One thing I try to do is after a hard run is to let the engine idle a few minutes
Gives it a little time to cool off before shutting down
As far as the term vapor lock- I don't remember seeing the issue discussed here
I only vaguely remember the term used with the old carbureted engines of the past

[Seaduck]

Yeah suzuki has battled vapor lock for many years. Here is a post on here talking about it.
http://www.suzukioutboardforum.com/s...r-support.html

[Moonlighter]

I do recall reading about some such issues with earlier models. Most people had no problems, but it did occur on some boats.

I recall that a solution for the more severe cases was simply to install a small low pressure electric fuel pump in the fuel line in the boat, not sure whether it was before of after the Racor fuel filter - probably after. That seemed to solve it.

But I agree with Art, keeping the engine cool is a key, and taking his advice to allow it to idle down for a few minutes after hard running is an excellent approach.

Then, the first thing I would do is to replace the water pump, and not just the impeller, do a full kit including the stainless housing! Housing might look OK but it has been found that even small deviations in its shape reduces effectiveness significantly.

At the same time, check and replace if necessary all the internal sacrificial anodes in the engine. Not sure how many there are in the V6's but sure to be at least 4, maybe 6.

If you find they are badly eroded, I would then do a big vinegar flush of the engine because it would indicate that in its earlier life it hasnt been well maintained and is likely to have at least partially blocked water passages. If you google "vinegar flush" on THT there is an excellent thread that shows you how to do it and the results.

[Lostsoul58]

Thanks for the help. The impeller is the next project. Don't understand the lack of engine temp gauge but I reckon most folks would ignore it anyway. Is there an online service manual available?

[redlowrey]

Has anyone found a conclusive fix for the notorious vapor lock issue?
I've spent a lot of money on fuel lines, filters, separators, bulbs, additives, & spark plugs and still have the hot soak-loss of RPMs during the summer weather.
Stumped. Pissed off. Embarrassed. Tired. Going broke.
Tank vent fine. Using Valvtect fuel from a Marina that pumps fuel nonstop.
There has to have been something that was found that stopped this madness...

There was, a water cooled fuel rail.

[artdf175]

The answer is yes but I didn't save the link Just search for Suzuki outboard motor manuals
However let me suggest just buying the full service manual
You will not be sorry you did
This site has them as well as Brownspoiht marine

Temp guage - I installed the engine interface cable that plugged into the NEMA 2000 backbone and I am able to get all the engine read outs on my Lowrance chart plotter
Something for you to look further into

Art

[Lostsoul58]

There was, a water cooled fuel rail.

I'll be damned...

You are the first person that has mentioned this.

Was this done by Suzuki?

I called the Suzuki Technical line and attempted to speak to the technician.
He couldn't understand my backwoods hillbilly accent and I couldn't understand his broken English (India?)

Anyway I asked for any technical service postings with the understanding that I was not trying to get anything free....

I was told that there has never been an issue such as I've described.

***. That was helpful.

Rant over...
Do you know if that fuel rail is available anywhere?

[Lostsoul58]

The answer is yes but I didn't save the link Just search for Suzuki outboard motor manuals
However let me suggest just buying the full service manual
You will not be sorry you did
This site has them as well as Brownspoiht marine

Temp guage - I installed the engine interface cable that plugged into the NEMA 2000 backbone and I am able to get all the engine read outs on my Lowrance chart plotter
Something for you to look further into

Art

That's about like brain surgery to me Art but I do appreciate your help.