Suzuki DF70 power loss

[5.5 mtr]

Hi all,
I have a 5.5mtr with a suzuki DF70 with no power. On the drive she runs absolutely fine revs to the limiter in gear in a test tank.
But in the water it won't rev past 1100RPM it's like trying to pull away in 3th gear in a car the engine bogs down and just will not pick-up.
I have brought a diagnostic program and it shows no faults at all and I have been through all the normal tests,compression,fuel pressure and plugs.
I am now at a loss of ideas and power any clues as to what the problem might be would be much appreciated.

[matata]

Just wondering how you measured the fuel pressure and what readings...also what compression did you get. What did the plugs look like?

[Old seahorse]

Hi 5.5mtr.
I had a Mariner efi in the past, and went through similar issue.
It turned out that the ethanol in the fuel was breaking down, and causing issues through the injectors and pump. Some engines seem very sensitive to the short life of some fuels. I then discovered that the Esso super unleaded fuel has no( or less ) ethanol , so doesn’t cause this issue. ( worth checking if this is still the case). Once cleaned out, I ran it on this fuel and had no further issues. Cost per litre is higher, but for my use, it was a good trade off.
Not sure if this may be the same issue for you, but worth considering.

[br1anuk]

This is a long shot but I had a similar problem with my 2004 Suzuki DF90. It turned out to be leaking exhaust gas from the rusted steel plug down the left hand side of the leg inside the cover that was feeding directly into the engine hood and into the air intake.
basically the engine was breathing in its own exhaust. I'td run perfect without the hood on but as soon as it was replaced it gave the symptoms you describe.
I'm not a Outboard engine expert but its worth checking.
I used some steel putty to block up the hole and it runs like a dream now.

https://www.thehulltruth.com/boating...ion-issue.html

[Limecc]

Originally Posted by br1anuk

This is a long shot but I had a similar problem with my 2004 Suzuki DF90. It turned out to be leaking exhaust gas from the rusted steel plug down the left hand side of the leg inside the cover that was feeding directly into the engine hood and into the air intake.
basically the engine was breathing in its own exhaust. I'td run perfect without the hood on but as soon as it was replaced it gave the symptoms you describe.
I'm not a Outboard engine expert but its worth checking.
I used some steel putty to block up the hole and it runs like a dream now.

https://www.thehulltruth.com/boating...ion-issue.html

How interesting. That thread references the DF140 until 2007, your issue was with an older DF90, no issue but my 2006 DF50 has certainly got the same exhaust plug.

Although an older engine it's got low hours, I'll attempt to remove and make an inspection next time I have the cover off.

[br1anuk]

Apparently there’s a replacement aluminium plug available on the internet if you do a search. Think it’s called Suzuki gold plug.
Mine had reacted with the aluminium and couldn’t be saved. Absolute madness by Suzuki engineers.

[Limecc]

Originally Posted by br1anuk

Apparently there’s a replacement aluminium plug available on the internet if you do a search. Think it’s called Suzuki gold plug.
Mine had reacted with the aluminium and couldn’t be saved. Absolute madness by Suzuki engineers.

Here it is: $20
https://goldplug.com/shop/outboard/

What were your internal anodes like?