I bought this 1990 F250 351w w/ ZF5. I finally got it all fixed up and running but the idle was weird. Found out today it had some broke vaccum lines. Okay, fix them, just to find my MAP is routed wrong, as is the short yellow vac line that SHOULD go to the BPV(pink). The MAP was routed to the ACV on the TAB, and the TAD line was plugged into this small PCV on the passenger side of the back of the engine. I've since plugged the ACV because I can't find one on the back of the engine. I can't find a BPV either! Perhaps because I don't have cats on the truck? I know the thermactor should be behind the engine but it's not there either. So I basically plugged these lines off. Now my truck is idling better and not trying to die when I press the accelerator. Why are these missing off this truck? Clearly someone was playing with vaccum lines chasing ghosts. Also can someone tell me what connects to the solenoid in the picture I've attached? Thats how it WAS attached, and that is not the ACV. That line has been since removed and for now I plugged that PCV. Thanks.

 

The part in the picture is the PCV valve.

Not saying that is correct for your truck but I believe the yellow vacuum line should go to the check valve on the crossover tube. The top port on the PCV should be capped off. The MAP sensor should go directly to the vacuum tree on the manifold.

Would you dumb that down for me so we are on the same page. What are you calling “ACV” ?

 

ACV is the Air Control Valve. It's a circular metal object similar in shape to the fuel pressure regulator. That is NOT the ACV nor does that connector fit in it right. I've attached what it should look like from a video. You can see the ACV behind that PCV valve in the image. It should have a small pinhole top that the connector fits on easily.

 

The back of the engine should look like this

 

Yeah that piece in the back doesn't exist on my 351. I'm guessing they did some emissions deletes.

 

I've tried taking a picture but as you can see that ACV is not on my 351w. So it must have been deleted and they didn't plug the vacuum lines.

 

No the air injection system on HD trucks is totally different., it should look more like this 7.5L setup.

 

Mine certainly doesn't look all like this. But I've capped off the ACV port and the BPV port. Properly routed my MAP, and fixed any other broken vac lines and she's running beautifully. A tad high idle warmed up at about 900RPM but no surging or missing.