[cguettler]

I was wondering what the hose at the back of the carb does. It runs behind the disk that controls the throtle. It has a very small diameter and is about 3 inches long. Thanks

[Laddies]

Tough question with no serial number, first I have never seen A 7.5 with a small hose attached to the carb as you describe. Are you talking about the bleed line thats on the crankcase, number 8? http://www.mercruiserparts.com/Show_...KCASE+ASSEMBLY

[beamin1]

Can't tell if that's the same diagram as this one but it's #8 on this one(pretty sure they're the same)... Mine has the same line running from the back of the carb to the #8 on the block....I assumed it was a vacuum line on mine ?

If yours is only 3" long I assume it's not connected on the other end, which would mean it's probably sucking air... you can see from the 2 links we gave you(pretty sure they are the same part) where it goes, there should be a check valve\90 elbow coming out of the block on the left side of the motor if your looking at it from the front, it should connect to there.