Truck is running like crap, of course I have to smog in October... so I figured vacuum leak was possible , started checking my hoses and one of the stupid little ones running off the diverter valve(fuel vapor line?) deteriorated in my hand. Fantastic. What is left of the smaller hose is red - and if I'm reading the diagram under the hood correctly this is the hose that runs around the back of the block to a "TAB SOL V" (solenoid?) on the other side... I'm assuming this is standard bulk hose available through the dealership? Also, please feel free to offer any corrections or component names if I had them wrong - I don't want to screw this part up; I realize I've probably answered my own question, but I am not in the position to remove the manifold and run all new vacuum lines at this point, and as they are protected by tubing and in a cramped spot I'd like to just run the one line now if I can get away with it(and the smaller ones that are easy to get to).... - 1991 f150 4.9 2WD 5speed

 

I got rid of all the plastic vacuum lines about 10 years ago and used metal brake line instead with a few inches of rubber line to join at the ends.
I believe most of it was 1/8" or 3/16".
A tubing bender makes for a nice job.

 

I have a 1990 4x4 with the 300 that suddenly started running crappy and will not idle. I pulled the PCV. It plugs into a grommet in the valve cover and has two ports. The large port runs back to the intake but I can't figure out what to do with the small port which is normally plugged. I can't believe the plug "blew out" but I can't find a loose vacuum line or any place to connect one to from the PCV. My diagram looks like yours.
I put in a new PCV and tried it both ways, plugged and open with no change which seems to mean that there is something else open

 

The newest of these trucks with a 300/4.9 are at least 16 years old. The hard plastic factory vac lines deteriorate developing anywhere from small cracks (hard to detect) to disintegration. Change them out with all rubber lines or do like tiap and use SS line. The caps used to plug off vac ports disintegrate too...especially the new ones currently available...they are junk. Inspect them frequently and replace as necessary.

 

Thanks, I'll take your advice but I still can't figure out what to do with that open port on the PCV...it's driving me crazy, or crazier

 

If it's open, plug it. If not, forget it.

 

If yours is a canadian 1990 f series, it takes a EV49B pcv valve.
It only has 1 3/8" port.

The top plug on a 2 port pcv valve can and will blow out if the engine has backfired thru the intake system.

You can either try and find the Ford part number or just block of the top port on what you have.

BTW, on some applications, the top port connects to the charcoal canister/purge valve system, so when the purge valve opens, the engine burns the excess fuel tank vapors.

 

I'm in Virginia and the truck was built in Norfolk, Va. Do you know where the charcoal canister/purge valve connection would be located or what it looks like? I have looked high and low...

 

The charcoal cannister is located under where the battery is located [passenger side, to the left of the radiator]. At least this is true of the carbureted models.

 

Pretty much where it is on my '91 EFI model. And it doesn't look so much like a canister, more like a small plastic box with a couple of ***** on top.

 

Yeah, they delivered the final blow at the dealership parts counter today - they don't carry it any longer and the parts guy said "just get rid of it and use different hose" or "check NAPA". I like your metal brake line idea - it's a pretty tiny line, tho. What did you do for the check valves, or did you bypass those altogether?

 

Mine is the same as yours, but the outlet goes across the engine and forks into the connection from the air intake and the intake manifold. Curious why it would fork into the same connection. Anyway, the last look I had of my F-150 was on a roll-back headed east.
Thanks for your time and your help. When I (they) figure out the problem I will post.

 

I just bought several 3 or 4 ft sections of brakes line in the sizes to match the fittings on the part joining to them like the solenoid valves etc.
I kept all the stock pieces like the check valve etc. Any rubber I can easily reach and the brake lines aren't bother being next to the hot items like the plastic lines were. When I took the pics today I noticed that I left 2 of the original plastic lines at the solenoid valves. I will probably change them out sometime. Some of my lines are 1/4". Keep in mind this is a van, a little tighter in spots.

Here is a pic of my exhaust pipe. I usually roughly gauge how well a engine is tuned by the soot in the pipe. I cleaned the pipe about 5000 miles ago and you get no black wiping your finger in the pipe, not bad for OBDl. No catalytic converter and e10 gas and 50/50 highway/city driving. Runs great, but I can't check the mileage, speedo broken.

 

I guess I had yours mixed up with another.

Here is a pic of the purge valve but keep in mind this is a 94 van, so location might be different.

I have not seen a vacuum hooked to the pcv on these 4.9 engines. the diagram posted above and my 94 diagram are the same, just the 3/8" line to the intake manifold for crankcase vapors.

I suspect you are having vacuum leaks like feeniks4.9.
Another thing to check is the egr valve to be sure it is closing properly.

 

Excellent - thanks for the pics, I have a clearer idea now. Unfortunately eliminating the cat is not an option in these parts, but I appreciate your sharing your idea, I may definitely do this!