Mystery Hose

[BJH324JH]

Okay, so I popped open the hood of my truck to check for any worn out hoses coming from the carburetor and to my surprise I noticed a hose was completely torn apart, maybe from old age? The hose that I am referring to is located to the left of the carburetor.

Here is a picture of the torn hose, right below this taped up hose (Taped and labeled so I wouldn't forget where the hose went):

https://s30.postimg.org/minpu9cdd/Oh_Oh.jpg

A closer look:

https://s24.postimg.org/t192a6v7p/20170107_204619.jpg

Can anyone Identify this hose so that I can replace it?

[pennyman1]

That probably goes to the box on the drivers inner fender. It is the vacuum signal for the computer controlled carb if you have the original carb. Open the box and replace the hose from there to the fitting on the intake. You should be having major issues with that hose being bad with running, especially acceleration, like falling flat on its face when pushing down on the gas pedal.

[BradMph]

Your hoses look like they could use some replacement. You can find where that hose goes by checking the vacuum line, smog related area of a manual. We have plenty of manuals here if you want to download one. Usually pasted under your hood is a sticker showing vacuum line mapping. See if there is one and that should help you locate your connection.

[BJH324JH]

That probably goes to the box on the drivers inner fender. It is the vacuum signal for the computer controlled carb if you have the original carb. Open the box and replace the hose from there to the fitting on the intake. You should be having major issues with that hose being bad with running, especially acceleration, like falling flat on its face when pushing down on the gas pedal.

Running bad, actually it's not running at all.

I took it upon myself to fix a lot of the issues that this truck has had, issues that were never taken into consideration by the previous owner. The truck has never been well maintained. Some of the parts that I recently replaced on this truck are the power steering gear box, master cylinder, upper and lower ball joints on both sides, both front calipers and brake pads, brake drums on both sides, brake shoes with new hardware on both sides, wheel cylinder on both sides, fuel pump, inner and outer tie rods on both sides, pitman arm, idler arm, and much more... This is giving me a headache, I don't know why it won't start. That's when I decided to check the hoses and ended up making this thread for some help. Now after looking more deeply at the hoses around the torn hose, I found a bunch of other sketchy looking hoses, hoses with screws in them??? I had a shop mechanic hook up the new carburetor because I wasn't confident in myself that I could do it, I was young and this was my very first vehicle, I didn't want to screw anything up, so I paid a shop mechanic to do it. Now looking back, I really should of considered doing the work myself because I have a feeling the carburetor wasn't properly installed. Although, it did run before, but not so well, so I'm thinking the no start condition that it is in right now could be one or all of the of these, the 32 degree weather and the thick oil the truck has in it right now might give it trouble starting (I think it might be the oil because the truck ran fine in sunny California, but now that I am in a colder state, it doesn't want to start any more.), or the starter is going bad. Also, I don't think that is the battery as I tested the battery using a multimeter and it checks out okay. The battery terminals are also squeaky clean. I believe that it could be the starter because when cranking, it sounds weak. Another thing that might be the problem is the oil soaked ground connections from the fuel pump. I replaced the fuel pump because of it leaking oil and some of the oil dripped to where the negative cable is grounded. I don't know if that will interfere with the starter operating as it should? It might also be that mystery hose? I just don't know, anyone have a clue what the problem could be?

Here is some pictures of other sketchy looking hoses around the carburetor:

https://s27.postimg.org/6ddd1o1r7/20170108_222346.jpg

https://s27.postimg.org/bdfencwrn/20170108_222518.jpg

pennyman1, as for the box you stated, is this the box you mean?:

https://s28.postimg.org/4qzynoo5p/20170108_222237.jpg

[DroppedMitsu]

Yes, that is the box he is talking about

[BJH324JH]

I cleaned up the ground connections soaked in oil and that fixed the weak starter issue. The starter then cranked normally after cleaning the ground connection, but it still would not fire up. An oil and oil filter change is what I did next. (Valvoline max life SAE 10W40 synthetic blend motor oil) Still would not fire up. After cleaning the oil soaked ground connections and replacing the oil and oil filter, I decided to check the spark plugs and what do you know, they were bad. I replaced them, and she fired right up! Now, there is good news and there is bad news, good news is it starts, bad news is it idles horribly for a few seconds and then shuts off. I am guessing this could be because of the Mystery hose that is ripped completely off. pennyman1 did say it will run bad without that hose. Another thing that could be bad, might be the distributor cap, rotor, or the spark plug wires. Anyone know why it idles for a few seconds then shuts off? It shakes the whole damn truck when it idles for those few seconds. I will try to take video of what I mean. Could it be that it's just cold and needs a while to warm up? I did have the carburetor tuned at the carburetor shop with their fancy computer and haven't touched any of the adjustments, so I doubt it could be the carburetor. Questions, Questions, Questions, ughhhh.

Thanks DroppedMitsu for confirming.

[pennyman1]

Don't think that the carb is set right because they used a computer - these carbs aren't tuned using one. To start the truck, press the gas pedal to the floor once, then release. Start the truck - it should go into fast idle about 2000 rpm. If it doesn't, then the choke is not working. A non functioning choke will do what you describe. If the choke is working, after 30 seconds, tap the gas pedal, it should then drop to fast idle, about 1400 to 1600 rpm. If you tap the pedal and it drops to idle, then the choke is not set right. You said this was a new carb - is it a new original Mikuni, rebuilt original, weber carb (beige choke) or a empi / webercarbdirect weber knockoff (black choke)? these different carbs are all different and have their own way of setting them up to run. Let us know what you got, or post pics.

[BJH324JH]

I think I may have discovered what the mystery hose is. I believe it is the vacuum hose for the air control valve. It connects to the thermo sensor, which is underneath the air filter body. (I bought a new hose and installed one end of the hose to the thermo sensor and the other end to the fitting where the "mystery hose" was torn of.) Makes me wonder how the heck the truck managed to run without this hose.
20170110_203052.jpg

This hose on start up creates a vacuum and makes this cool looking door rise at the air control valve. Once the air filter body warms up to 133°, the thermo sensor kicks in and the vacuum begins to leak, causing the door to come down. This might be where the mystery hose goes, but I'm not 100% sure. Here is a picture on the manual that makes me think I might be right.

https://s30.postimg.org/vqp1kpudr/20170110_173554.jpg

Video of Air Control Valve in Action:
http://s000.tinyupload.com/index.php...87239883847913
Video file will automatically delete if not downloaded for 100 days.

[BJH324JH]

Don't think that the carb is set right because they used a computer - these carbs aren't tuned using one. To start the truck, press the gas pedal to the floor once, then release. Start the truck - it should go into fast idle about 2000 rpm. If it doesn't, then the choke is not working. A non functioning choke will do what you describe. If the choke is working, after 30 seconds, tap the gas pedal, it should then drop to fast idle, about 1400 to 1600 rpm. If you tap the pedal and it drops to idle, then the choke is not set right. You said this was a new carb - is it a new original Mikuni, rebuilt original, weber carb (beige choke) or a empi / webercarbdirect weber knockoff (black choke)? these different carbs are all different and have their own way of setting them up to run. Let us know what you got, or post pics.

The carburetor is a remanufactured Mikuni carburetor that I bought from NationalCarburetors.com through Amazon, https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

How exactly will I know if it will go into fast idle upon start up?

[pennyman1]

The choke plate will close all the way when the pedal is pushed to the floor and the truck will idle high: the plate will open slightly on the first tap of the pedal the speed of the motor will drop some. You will have to have the top of the air cleaner off to see this of course.

[BJH324JH]

The choke plate will close all the way when the pedal is pushed to the floor and the truck will idle high: the plate will open slightly on the first tap of the pedal the speed of the motor will drop some. You will have to have the top of the air cleaner off to see this of course.

So by flooring the gas pedal before starting the truck, the choke plate should close all the way and this is visually visible by removing the top of the air filter cover and looking directly down the carburetor? If this is the case, then I didn't see the choke plate close, or any part move. Even when the truck starts, I still see nothing move down inside the carburetor.

[geezer101]

Either your auto choke is dead or it needs to be adjusted. Tap the choke butterfly with the engine off and cold and see how it reacts. If it sort of snaps shut it needs to be adjusted. Even with the engine cold starting the primary throat should be able to generate enough air flow to cause the butterfly to sag a little.

[BJH324JH]

Either your auto choke is dead or it needs to be adjusted. Tap the choke butterfly with the engine off and cold and see how it reacts. If it sort of snaps shut it needs to be adjusted. Even with the engine cold starting the primary throat should be able to generate enough air flow to cause the butterfly to sag a little.

Thanks so much everyone for the help. I am convinced it is the carburetor that is the problem. I think that the carburetor is not adjusted correctly. As for the Mikuni carburetors not needing a computer to adjust them, I wonder why the carburetor shop used a computer to "adjust" the carb? Was it all for show, because honestly, I just saw the guy get in the truck and gas it and the other guy did something to the carburetor, I just couldn't see the guy adjusting the carburetor because they wouldn't let us do to some insurance thing??? They adjusted the carburetor in less the 3 minutes. Did I get ripped off? Payed about 60 bucks to adjust the carburetor.

[geezer101]

The only form of electronic tuning they can perform on a neanderthal tech carb is a gas probe in the exhaust and manual adjustment of the air/fuel mixture screw. If you know what order to adjust the screw settings you can 90% debug a poorly adjusted carb pretty quickly. The main problems with the Mikuni are usually some monkey with a phillips head screwdriver has tried to correct a tuning fault with the carb first and not the timing, or running the carb way past it's rebuild interval and it fouls up. If the $60 ironed out your running issues then you have broken even. It'll be continuous run ins with shops eager to empty your wallet that will motivate a guy into rolling up their sleeves and learning anything they can about nuts and bolts. Small shops prey on your ignorance and when something goes wrong you are at their mercy. Sorry about the rant...

[pennyman1]

Look in our manual section for the adjustments for your carb - at this point, turning a few screws for the choke can only improve it. Also spray the linkages on the carb with carb and choke cleaner, not air intake cleaner. Carb and choke cleaner has a light oil with the cleaner to lube the linkages, air intake is strictly cleaner.