2006/7 twin bf 225 dgital gauges dont show gph

Hi guys
i convert a grady 268 islander 2000 from single yamaha 250 ox66 to twin honda 2006/7 bf225
i did it my self with help of a friend because the local dealer refused to install "if i don't sale the engines i don't install
them"
so now after installing the engine they running flawless
i used the old round two button digital gauges ,
on the speedometer i don't get the gph reading at all
the speedo connect to one of the instrument harness by a square brown plug. & it's have a small round plug no idea for what?
Is both instrument harnesses get connected together any where & if so how?
Any help will greatly appreciate

thank you noam

See my post # 11 at http://www.marineengine.com/boat-forum/showthread.php?416165-2006-HONDA-225-Fuel-Computer

That may help.

Ooops. The speedometer is driven by the pitot tube that's on the front of the engine and runs all the way to the speedo. That gets clogged up at the engine a lot. So a lot of folks, like me, just plug the tube from the engine and install a separate pickup on the transom like this one...

https://www.amazon.com/SeaLux-Marin...coding=UTF8&psc=1&refRID=RG2NYM7S65F9CQKCC41P

chawk_man said:

See my post # 11 at http://www.marineengine.com/boat-forum/showthread.php?416165-2006-HONDA-225-Fuel-Computer

That may help.

Click to expand...

thank you chawk for reply
the drawing show only one engine & one speedo hook up
how its works with twin?
is there any harness i missing ?
how the two engines link to the speedo?
thanks again

Your are well beyond my area of expertise when it comes to rigging. Hopefully one of the folks on this forum who knows what they're doing in the rigging arena will jump in.

You might want to take a look at the accessories page on Honda Marine to see what harnesses are available.

chawk_man said:

Ooops. The speedometer is driven by the pitot tube that's on the front of the engine and runs all the way to the speedo. That gets clogged up at the engine a lot. So a lot of folks, like me, just plug the tube from the engine and install a separate pickup on the transom like this one...

https://www.amazon.com/SeaLux-Marin...coding=UTF8&psc=1&refRID=RG2NYM7S65F9CQKCC41P

Click to expand...

speedometer works fine