What Is This ?

[DUBLR]

I have an 03 HO. On the passenger side mounted on the firewall )top left facing the truck) there is a black pump. A small tubing runs accross the cowling then down the opposite wheel well (need to follow it further).



This unit runs when you turn the ignition on then quits. Lately it is running all the time... . worried about a failure. Is this a fuel primer or anyone know? Also comments about it running when the engine is powered up?

 

[Scrappy]

Is your truck an auto? my guess is that it is a vacuum pump to run the cruise, but I don't know what else it does. I have seen an '04 auto with this same pump. I don't know when it is supposed to run but I think it would work with the cruise on(not engaged) and engaged.

 

[DUBLR]

Yup, an auto. I suspect the same and that I have a vacumm leak.

 

[jwduke]

Humm, for some reason I thought the 48RE didn't need a vacuum source, but anything is possible.

 

[DUBLR]

Figured it out... . this is a vacuum pump for the crusie control. There were pin holes rubbed in the tubing. 70,000 miles and dirt roads but seems too fragile to wear out altrady. Hoping the server is not bad... this thing is really buried.