318 down

[Intrepolicious]

Unbelievable! I go out this morning and she starts right up (like she should!) and I let her sit and idle for 10-15 minutes to get up to temp, hop in and drive her up to the grocery store. Shut her off, go in the store, come back out (10-15 minutes later) and she starts right back up (like she should!) and i drive around the neighborhood for a few minutes like everything is normal and nothing ever happened...

AJ, I'm thouroughly convinced it's that jumper, or something at the tank. There's no other explanation for the way it acts with that 3/4 or more in the tank. Right now, with just a hair over a half of a tank, she runs perfectly! No stalls, no no-start conditions, no issues at all! Just like last time... to the "T"!

So my plan is to run the tank down as low as I can, then pull it. I don't suppose you have any pics of said jumper? Or any pics of the top of the tank in general? Any tips, or other things I might need to look out for when pulling the tank? I guess I could wait until my Engine Performance Manual arrives..

 

[BudW]

You need to plug all of the un-plugged vacuum ports.
You can purchase a package of multi size caps - or get some short pieces of hose, then insert a small screw or stick in the other size.

With un-plugged vacuum hoses - it will be hard to diagnosis any problem on the car.

 

[Intrepolicious]

You need to plug all of the un-plugged vacuum ports.
You can purchase a package of multi size caps - or get some short pieces of hose, then insert a small screw or stick in the other size.

With un-plugged vacuum hoses - it will be hard to diagnosis any problem on the car.

I think everything's already plugged off Bud. Unless you're seeing something I'm missing?

I finally got around to cleaning all of the acorns out of the intake manifold. (I've only owned this car for a few weeks now!) I think this car sat for a while and some squirrels made a nest in the top of the engine lol.. there was a ton of acorns!

Anyway, I cleaned and vacuumed all the acorn debris etc out of there finally, and took some hi-rez pics. Uploading now...

 

[Intrepolicious]

Here's a few more pics after cleaning out the acorn debris.

 

[Intrepolicious]

This one is the "hi-rez" I believe

 

[Intrepolicious]

Note: I did pull that PCV valve out.. so that's why it looks loose. I need a new grommet and probably a new PCV valve itself.

 

[Intrepolicious]

Left side

 

[Intrepolicious]

Right

 

[AJ/FormS]

Comments in the quote

Unbelievable! I go out this morning and she starts right up (like she should!) and I let her sit and idle for 10-15 minutes to get up to temp, hop in and drive her up to the grocery store. Shut her off, go in the store, come back out (10-15 minutes later) and she starts right back up (like she should!) and i drive around the neighborhood for a few minutes like everything is normal and nothing ever happened...

AJ, I'm thouroughly convinced it's that jumper, or something at the tank. There's no other explanation for the way it acts with that 3/4 or more in the tank. Right now, with just a hair over a half of a tank, she runs perfectly! No stalls, no no-start conditions, no issues at all! Just like last time... to the "T"!
I no longer think it is the jumper! If it was, it would be getting worse as the fuel level drops. In the jumper scenario, the falling tank level would make it harder for the pump to pull up the fuel, so it would rather pull air in the jumper, So eventually you would have nothing but air in the line. So kick that dog to the curb, Go look for something else.

So my plan is to run the tank down as low as I can, then pull it. I don't suppose you have any pics of said jumper? Or any pics of the top of the tank in general? Any tips, or other things I might need to look out for when pulling the tank? I guess I could wait until my Engine Performance Manual arrives..Don't waste your time, I'm pretty sure your jumper is ok.

 

[AJ/FormS]

Say,Bud; do you remember how that bowl vents? Does it vent into the airhorn beside the hold-down system? There is no adjuster under that flat tin plate,right?
Or does it vent back to the canister?
You know what I'm thinking right?
OP has stated he heard a whosh when opening the gascap. That's not supposed to happen. The tank is supposed to vent into the canister, and so is the float bowl. Since the tank is not venting properly, maybe neither is the floatbowl.
But if the tank is pressurized, it will add it's pressure to the pumps pressure, and maybe the float valve cannot handle it. I heard the Op say he had driven around with gascap off, and it still does this, so one might rule that out.
So that takes me back to the canister. I see the big fat bowl fume- collector hose is still on the carb.
So what triggers the canister purge? I think I see the trigger hose is still on there

Oh I see it now! The vacuum advance hose is hooked to venturi vacuum, and the purge hose is hooked to the spark port.
Am I right?
Well that's messed up.
That would trigger the canister purge right off idle, and it would go straight to 100%, instead of being modulated by the venturi vacuum.And I don't think the venturi port has enough power to operate the vacuum advance, and if it did, it would be very late in coming in.

OP,wait for Bud to chime in and verify. or not. But I think you are gonna need to swap those two hoses around.
I had a Clymers for an 84 but I can't find it just now.

 

[Intrepolicious]

Comments in the quote

Gotcha. Hey if I don't have to pull the tank, I'm not going to be mad about it lol. I would like to figure out what the issue is, but there's no hurry; I have all the time in the world to play and troubleshoot. (I'm actually enjoying all of this!)

Say,Bud; do you remember how that bowl vents? Does it vent into the airhorn beside the hold-down system? There is no adjuster under that flat tin plate,right?
Or does it vent back to the canister?
You know what I'm thinking right?
OP has stated he heard a whosh when opening the gascap. That's not supposed to happen. The tank is supposed to vent into the canister, and so is the float bowl. Since the tank is not venting properly, maybe neither is the floatbowl.
But if the tank is pressurized, it will add it's pressure to the pumps pressure, and maybe the float valve cannot handle it. I heard the Op say he had driven around with gascap off, and it still does this, so one might rule that out.
So that takes me back to the canister. I see the big fat bowl fume- collector hose is still on the carb.
So what triggers the canister purge? I think I see the trigger hose is still on there

Oh I see it now! The vacuum advance hose is hooked to venturi vacuum, and the purge hose is hooked to the spark port.
Am I right?
Well that's messed up.
That would trigger the canister purge right off idle, and it would go straight to 100%, instead of being modulated by the venturi vacuum.And I don't think the venturi port has enough power to operate the vacuum advance, and if it did, it would be very late in coming in.

OP,wait for Bud to chime in and verify. or not. But I think you are gonna need to swap those two hoses around.
I had a Clymers for an 84 but I can't find it just now.

I'm going to record a short video so you can see better. Standby...

 

[Intrepolicious]

Well, my phone is having trouble uploading now.

 

[Intrepolicious]

 

[Intrepolicious]

I heard the Op say he had driven around with gascap off, and it still does this, so one might rule that out.

That hasn't exactly been verified. I tried running it (just idling) for a while sitting in the driveway. I haven't gone out driving around without the cap on, nor verified it gave me the same "whoosh" effect.

But.. I'll try it!

 

[Intrepolicious]

Here's a couple more pics. I tried to get the canister in the shots this time.

 

[Intrepolicious]

What about this?

 

[Intrepolicious]

Oh... I think I found something! Might not be that significant, but it's something! Ya see that plug in the picture above.. right below the red "W"? Looks like it's plugged right?

 

[Intrepolicious]

Oh... I think I found something! Might not be that significant, but it's something! Ya see that plug in the picture above.. right below the red "W"? Looks like it's plugged right?

NOT!

 

[Intrepolicious]

So I put a proper plug on that one, and plugged the little skinny one as well.

That got rid of the whistle! Preliminary results are; started right up and ran like a champ around the neighborhood. I let it warm up for a few, then took it out around the block, up to about 45mph for a few stretches, and did a couple semi-hard brake tests to see if the kickdown to idle was good... didn't stall one time!

Maybe that fixed it...

 

[AJ/FormS]

According to the colorized diagram in post #76,your routing is correct.
According to the one above it, your routing is wrong
Oh, I see you found something. Yahoo!
Now if you if she stalls again, pull the bowl-vent hose off the carb, that is the big one at the front, the highest one. Then roadtest again.
Now You really need to prove the tank is vented. You can do this by first removing the gascap. Then go to the canister and find the hose that goes to the back. Have a helper standing close to the filler tube, while you blow compressed air into that line. The compressed air should be exiting the tank, perhaps making a bubbling sound. Your helper should be able to hear it, smell it, and maybe feel it. NO SMOKING!
If you cannot prove the line is open this way, then you will have to get under the car and find that line. Remove the rear jumper,and back to the compressed air deal. I might aswell tell you that that little 3/16 line is known to rudt up at the lowest place. Water/condensation gets in there and then she plugs right up. This line has to remain operable. The engine will give you fits if the tank does not vent. You could vent the tank differently, but if you defeat the canister, then your hard-earned dollars will fly away. Furthermore, if you disconnect the canister completely from the carb, then your engine will run rich.At the bottom of the canister is a 5" or so filter. That system is designed to store vapors when the engine is off, and then when conditions are right, it feeds those vapors back into the engine. It does this by drawing air in the bottom,thru the filter. That air then gets mixed with the vapors, and sent into the engine for burning. Sooner or later the vapors will all be purged, and then the carb draws just air there. If you disconnect the canister, then you lose that calibrated air leak. So the A/F goes rich. You cannot compensate for this, with the mixture screws.
So long story short, a good working canister system is guaranteed to save you gas money.Try to get running properly.