I have a vacuum hose near the master cylinder that is flared at the end like it should be attached to a fitting, but there is nothing near it to reattach it too.

Anyway I am having a bit of an issue with my truck and the flashing SES light, I have googled it and have learned as you all know that it's a cylinder misfire. My fuel mileage is now between 11-12.5mpg on a 99 4.3L Blazer and i get a crazy amount of fuel smell outta the tail pipe, gotta figure this crap out soon. Any ideas? Regardless that isn't my real question, in looking around the engine bay I realized I have a hose disconnected. I don't know for sure if it supposed to be connected to anything or not, but since I am having a cylinder misfire I figure I should look into it. I apologize for not having any pictures and if anybody needs a shot of it I will try and get one this evening. This hose (pretty small diameter, maybe 7/32") runs out from what appears to be some kind of regulator or something to the right of the TB and runs over the top of my master cylinder and into a T-fitting. The hose in question is the one that runs to the right out of that fitting. Can you guys peek under the hood of your 4.3's and see if that hose runs to anything, especially anyone with a 99. If it does a road map to help me find where it needs to go would be huge. I've noticed it before but didn't sweat it until this thing started running so crappy. Thanks for any light you folks can shed on this issue.

 

There's TWO t-fittings in that area. I can't find a vacuum hose map in the service manual. but.... the hoses that hook into 'em, hose coming from the intake manifold: vacuum source. hose to the solenoid at the top lip of the firewall, center of engine compartment: that locks in your front axle in 4WD Hose going into hard clear plastic line: that goes down to a vacuum reservoir (or HVAC controls?). (one more mystery hose, possibly to control valve on secondary air pump?) To plumb it: The line coming from your intake has to go into a black/white check valve on the "first" t-fitting, after that center line goes to the second t-fitting & hook any of the other hoses to any available three open spots on the T's A leak in ANY of those lines is a direct vacuum leak to your engines point of view

 

There is a small male connector in a recessed space on the inner fender that the three inch hose in question presses into. I have not taken the fender apart to see what it is but from experience I searched for the same connection...

Good luck...

Brian

 

br
Did you find where that small vac line goes into the fender

 

I did. It's a challenge to see but it can be felt under the bracket that holds the antilock brake motor.

Thanks for asking. I hope this helps someone else.

 

Thank you. Because of you I finally found my vacuum leak.