I have a 78 F150 4X4 351M C6

I am a rookie when it comes to these trucks. so go easy on me.
I have searched a lot of threads and posts and have a few questions.

the vac lines are a total mess from the previous owner. the truck has
many open ended vac lines and nipples also some that looped in a circle.

I know it is hard to help when the truck is not in front of you.
I do have pics in my gallery.

I need to know what goes where ?
what don't I need?
What might I be missing?

I want to know what is needed especially for A/C to work properly.

since I plugged most of what I think I did not need it seem to run better for sure.

just wont idle on its own. I need to crack the throttle and hold it to keep it idling


coffee can next to battery...
.


2 port Thermo vac



Junction block and 2 round things behind the vacuum block.
Also the vacuum port for the choke is not even connected.



Manifold vacuum port what should it go to ?



Thanks again for all the help!!!!!!

 

One more pic.

The Dizzy vac advance is plugged in directly to here. lower port to left of fuel filter.

 

This one is correct.

 

Coffee can is the evap canister (I may have Called it the wrong part) but you should have one hose going from gas tank to the canister and then the other one should hook up to the exhaust manifold... I think? Not sure on the second hose. But if you search evap canister I'm sure NumberDummy has posted the picture of that set up multiple times.

Sorry I'm not knowledgeable enough to help on the rest.

 

Thanks for the help !
my original gas tank did not have the evap vent hole on the top of the tank.
I just put in a new tank and I got the same type of tank without the evap
vent hole.

 

Then you can disregard the coffee can. You might be wise to just toss it on the shelf and not throw it away because Californians are always looking for evap parts to make their trucks Legal.

 

Thanks again, very much appreciated.

I don't don't plan on removing the coffee can for now.

I noticed it still has the EGR plate on it in the back.

after about 2 hours of youtube surfing for 2150 videos.
I learned some good things that helped me a little.

the good :
I plugged a bunch of open ended nipples.
I removed some hose that kind of looped back to itself.
after very minor tinkering I got it to idle.

The Bad:
I still need to know how to properly route the vac hoses.
This carb seems to need a good quality proper fuel and idle adjustment. I have no idea how to adjust a carb.
I probably need a proper rebuilt CARB for my make model truck. I am Not sure what is on it
the choke will never work on this truck. Seems previous owner had no clue and it appears to be messed up beyond repair.

going to dive in to it tomorrow depending on weather. I don't have a garage to work in. wish I did but I don't.
I just want to get it running reliably so I can drive it and enjoy it.

Thanks again for all the help!

 

Nope, you got it right (sort of) because evap is one of it's names, along with "charcoal canister" or probably one or two others. But that's not it!
On a '78 the EVAP/Charcoal canister is mounted down on the top of the passenger frame rail, just below the battery and behind the radiator. It does have some of the hoses you describe, where the small one comes from the tank vent(s) and the large one goes up to the air cleaner housing.
The second large one is just an ambient pressure vent and is capped with a "mushroom" vent cap.

But the canister in the picture is a factory vacuum reservoir. I forget what they vacuum lines go to at the moment, but will find my chart. The '79 chart I have may very well match the original routing of the OP's '78, but there were just as likely four or five different iterations of it back in the late seventies when they were still learning about all this stuff.

Yep, I say wait for NumberDummy (or Rich/78-79) and one of their diagrams.
The '78 and '79 trucks could have had three, four, or perhaps even more of the coffee can and soup can and little round ball vacuum reservoirs under the hood. Mine has three if I remember.

To i w, your pictures are a bit small, but while your current vacuum advance hose may be workable, as fordguy said, it's not original. The original routing would have been through one of the temperature switches (TVS, for thermal vacuum switch I think they were called) and would have had a convoluted routing. But for now, with most of your smog stuff either disconnected or just not working, keeping the vacuum straight to the carburetor is the way to go. But when I run into this, I will often switch back and forth between straight "manifold vacuum" and the "ported (or "timed")" vacuum port on the carburetor.
Depending on the engine setup, yours might run better when done one way than it does the other. That's been my experience at least.

Sounds like you were on the right track by plugging up any open vacuum ports. Missing and cracked hoses make for a ton of vacuum leaks. A hose does not have to be capped if it's not connected to vacuum at the other end, but when in doubt, cap it off! Any open port however, should be capped off if it goes to a vacuum source. Or when you're not just not sure.
Your idle issue could just be adjustments. Start by adjusting the idle-air mixture screws first, to see if you get an increase in engine speed. If not, or if it's not enough, then adjust the idle speed screw until it reaches an idle speed that can be maintained for now.
In general, you want the idle to be down in the sub-700 mark, perhaps 600 in neutral and 500 to 600 in Drive for an auto trans. But not more if it can be helped, or you may have rough shifting out of gear and too much creep when at a light, or more heat from the trans.

If it won't idle down below 700 rpm you probably still have vacuum leaks, or need a further tune-up. Or the carb is not set up correctly where the linkage might be bound up slightly. Either the throttle linkage, OR the choke linkage can do this.
But that's for too high. If your idle is too low like it sounds, start with some adjustments. Because it's going to be some work to get all the vacuum lines back where they belong.
Assuming you even want to go there that is... Depending on the condition of many components, you may not even be able to re-connect them.

Search for some vacuum diagrams to get you started. I'll try to find the one for my '79 which should at least be of some help.
In the meantime I'll check out your gallery too, but if you can post up some higher resolution shots of the overall engine compartment so we can get an idea of what all is there, that would be great.

Paul

 

Sorry, guess I missed the part where you got it to idle! Oops!

You've reached at least your first milestone then. The rest is cake.
(ok, so it's rotten, wet and ugly cake, but hey, it's cake!)

 

LOL I love Cake !!!
I posted the actual pic size and it was HUGE ! I had to size them down.

Thanks for the helpful info. I will probably want to just remove the smog. no need for it here.

After looking at the mess under the hood for a while. ( my back will need a heat pad for sure.)
I don't have any hoses going to any EGR smog parts. So eliminating smog is fine by me. The truck
is exempt from any smog here in Virginia. I am nervous about air idle adjustments. I got a vacuum
gauge yesterday. now that it idles when warm maybe I can now check the vacuum to at least see
where it is at. I need to get a Tachometer soon to help with the tuning process. I should just hook
up the necessary Vacuum hoses needed.