225 IAB Valve

I think I might have found why my fuel use is quite high and performance not as good as I would expect.. The IAB actuator and valve are jammed solid and clearly not opening when supposed to !!!

First time I've heard of one of those failing. How did you figure that out?

I Spoke to a dealer who really knows his stuff. He was involved in the Honda F4SA series racing that used to be popular over in the UK and clearly knows the 225 inside out.

He suggested I check the IAB valve by just trying to move it manually.

You can see the actuator at the bottom of the engine it should be fairly easy to move by hand. If you cant move it them you need to strip off the intake manifold cover.

Then you just unsrew the actuator and remove it, then undo the screws that hold the spring plate onto the end and finally unscrew the two valve flaps from the rod that runs through.

Then you can twist the rod back and forth (use WD40 to free it up a bit) then as you twist it pull it out. Then you can clean the rod and the holes it runs through. I used a little vaseline to lubricate it then slid it all back together and re attached everything.

If you take a look at this video on you tube you can see what it should do. http://www.youtube.com/watch?v=YFhcC5M1HRM

(When the engine is off the spring hold the the valve open, then as soon as you fire the engine up the vaccuum valve actuator closes the flaps until you hit 4k RPM at which point the flaps open again)

EXCELLENT! Thanks, Chris.

In the second picture, what is the part called that looks like a brass flying saucer (that is where you attach the hose to)? I cannot seem to find a part number or replacement anywhere for my BF250 XXA 2013

That brass "flying saucer" is the IAB vacuum diaphragm. It is not a separate part and supposedly integral the the IAB. The whole assembly costs over $340 on boats.net. Don't ask me why I know that. HOWEVER, if the diaphragm is your only problem, you can probably find a substitute. It looks pretty standard and I've seen similar ones on Honda auto engines. So search around the Internet and try to find one.

See this link: http://www.boats.net/parts/search/H...d Later/BF250A XXA/INTAKE MANIFOLD/parts.html

Send me an e-mail at [email protected] and I will return a full write up of disassembly, testing and re-assembly, with an explanation of exactly what the IAB does.

Do a search on Honda part number 17129-P72-000. Not sure it is a replacement, but looks similar. If you have a Honda parts shop anywhere near by, take your diaphragm to them and see if they can come up with a match.

Thank you - I'm hoping I don't have any issues - will test it when I replace the fuel filter. Just wanted to make sure if I had a problem I could try to fix it, or barring that know where to buy parts.

Testing it is simple. Remove the vacuum line. Use needle nosed pliers to push the arm that is connected to the IAB shaft all the way into the diaphragm. Put your finer over the opening where the vacuum hose connected and let go of the pliers. The arm should come out a little bit, then stay in place. Remove your finger and the arm on the IAB should snap closed.

chawk_man said:

Testing it is simple. Remove the vacuum line. Use needle nosed pliers to push the arm that is connected to the IAB shaft all the way into the diaphragm. Put your finer over the opening where the vacuum hose connected and let go of the pliers. The arm should come out a little bit, then stay in place. Remove your finger and the arm on the IAB should snap closed.

Click to expand...

Tested and working fine. Thanks!