Where does this hose go?

[Fry]

While investing another issue ( coolant leak under passenger dash) I was looking under my hood to see where my heater core was bolted in and noticed this hose was disconnected on my FAST EFI . I did some looking around and didn’t see anywhere to connect it. Anybody have a clue?

https://imgur.com/a/7zundCP

 

[Broncobowsher]

Boost reference hose. The fuel pressure is a setting above the pressure sensed in that hose. With a carb, atmosphere pressure (open ended hose) is perfect. Doing a blow through carb, put that hose on the carb hat so it can reference that air pressure above the carb.

With port EFI, goes to manifold vaccum. This adjusts fuel pressure across the injector to a constant pressure regardless of vacuum. With it disconnected the manifold vacuum will pull fuel through the injector at a higher rate. The compensation drops the fuel pressure so the added vacuum doesn't add extra fuel.

 

[Fry]

Will it cause any issues if i
Leave it off?

 

[Broncobowsher]

Is it port injected? Just hook it to manifold vacuum. If you want accurate fuel management. If you want poor fuel management, leave it off.
Throttle body, leave it off.

 

[ba123]

I would bet you have a spot to connect it and you just don’t see it, leaving would leave a vacuum leak to that spot and your engine wouldn’t be running perfectly.

Just find it.

 

[Fry]

Is this possibly it?

https://imgur.com/a/cNgV6Kv

I don’t want to stick this hose in a place it doesn’t go.


Edit. After doing some googling that’s definitely not it.

 

[ba123]

No, that looks like your heat/ac drain or some other sort of drain tube.

Look for a spot on the intake or the base of your carb.

 

[m_m70]

drivers side air vent drain maybe?? As stated, not the place to connect.

 

[Fry]

https://imgur.com/a/A6GKPPe

Anybody see where it goes? Still scratching my head .

 

[Broncobowsher]

The first two pictures I see a vacuum tree. One of the vacuum ports is capped with a bolt shoved in the end of a hose. I can see another port is just capped with a simple rubber cap.
I would start there.

 

[ba123]

The first two pictures I see a vacuum tree. One of the vacuum ports is capped with a bolt shoved in the end of a hose. I can see another port is just capped with a simple rubber cap.
I would start there.

Yeah, maybe someone found a vacuum leak and just plugged it instead of connecting the hose that came off of it.

I'd connect there and if you find another open vacuum port somewhere at some point you can cap it, but if you don't, I'd be comfortable with that!

 

[Wild horse 75]

The hose end needs to be tightened up severely. There should be less than a hacksaw blade width between the nut and fitting. Plus if that hose isn’t designed for hose end you’ve got a leak waiting to happen.
As for the disconnected vacuum hose look at the instructions for the FAST system. It most likely doesn’t need to be connected to anything. Just remove it and leave the regulator vented to atmosphere.

 

[ba123]

The hose end needs to be tightened up severely. There should be less than a hacksaw blade width between the nut and fitting. Plus if that hose isn’t designed for hose end you’ve got a leak waiting to happen.
As for the disconnected vacuum hose look at the instructions for the FAST system. It most likely doesn’t need to be connected to anything. Just remove it and leave the regulator vented to atmosphere.

You might be right if that’s a carb in that pic and not Never discussed that. Good catch, @Wild horse 75

 

[m_m70]

looks like it has "FAST" cast in the throttle body......

The picture in post #1 looks like a pressure regulator with one fuel line connected, a mr gasket 1-15psi gauge and the vacuum line not connected to anything. I can't tell from the pic if it's actually functional or not as I would assume the throttle body would need more pressure??

Really need better pics. At least take the air cleaner off

 

[73azbronco]

it runs now? Take hose off, PO probably put it on and realized he didnt need it hooked to anything, left the hose on. I would not plug it though, leave open.

as previously noted, only used if you have boost.

 

[73azbronco]

Boost reference hose. The fuel pressure is a setting above the pressure sensed in that hose. With a carb, atmosphere pressure (open ended hose) is perfect. Doing a blow through carb, put that hose on the carb hat so it can reference that air pressure above the carb.

With port EFI, goes to manifold vaccum. This adjusts fuel pressure across the injector to a constant pressure regardless of vacuum. With it disconnected the manifold vacuum will pull fuel through the injector at a higher rate. The compensation drops the fuel pressure so the added vacuum doesn't add extra fuel.

It's interesting, some of these are for use with vacuum, and its called a vacuum port, so hook to vacuum on a fuel injected motor. Others show this as a Boost port, and only use if boosted. So, verify part number go to FAST website and see which one this is.

 

[Fry]

it runs now? Take hose off, PO probably put it on and realized he didnt need it hooked to anything, left the hose on. I would not plug it though, leave open.

as previously noted, only used if you have boost.

Yea it runs fine. Sometimes when I put it in reverse and back up out my garage it will die. But starts back up right away. I think maybe I don’t let it warm up enough. I did have a visitor at my neighbors house see me leave one day and we got to talking. Said he was a mechanic for like 25 years and it sounded like I had a vaccum leak.

 

[ba123]

Yea it runs fine. Sometimes when I put it in reverse and back up out my garage it will die. But starts back up right away. I think maybe I don’t let it warm up enough. I did have a visitor at my neighbors house see me leave one day and we got to talking. Said he was a mechanic for like 25 years and it sounded like I had a vaccum leak.

Then you prob do have an open fitting. You can try misting water or something and see if any reaction. Let it warm up first.

 

[73azbronco]

well swing that hose around an arc and I bet you find where it was connected.