Need Recommendation, Solenoid Valve

[imp]

Which of the numerous solenoid-operated vacuum valves found on our cars might be used to control vacuum to a selected place. My SN95 has one which might fit, tucked in on the RH firewall with control wires running downwards, the vacuum feed coming directly from the upper intake manifold, the controlled vacuum line going downwards and disappearing in the maze of harness which must go to the PCM. Might it be used?

Or, perhaps canister purge solenoid? I am devising a time-delayed vacuum shut-off for reasons I'll go into later. Thanks! imp

 

[jrichker]

Please provide the wire and stripe colors; with those, we may be able to identify the valve function.

 

[General karthief]

Are you looking for a close on command or open on command?

 

[imp]

Please provide the wire and stripe colors; with those, we may be able to identify the valve function.

They are Red and GY/YL. But, I've discovered a mystery here which may be more solvable by you guys who have much more experience with Fox/SN95s.

While I had the upper intake off, I noted the vacuum hose going to this solenoid looked pretty maggoty, and had a splice in the middle, to boot, so I replaced it. Look at the pics I just took, please.

It's tucked down inside the loop of A/C pipe, it's electrical connector down below. The RH hose goes directly to manifold vacuum. The LH hose, very rough looking, if touched, the fingers come away covered with Carbon Black, the hose disappears into the area between the fender splash shield, and inner fender well. This is all RH side at firewall. Doesn't look at all like Ford placed it there, to me.

Here it is pulled up out of it's hiding place. It has no markings of any kind to identify it, as a Ford OEM part would. I removed the connector, pinned it connected to my VOM, had wife turn key on. I expected this thing was some kind of vacuum controller for the climate system. WRONGO! 12 V present key on, no accessories on.

I took off the crummy looking fender-hole hose, attempted to blow through the valve, it's closed, no surprise. Then I SMELLED GASOLINE! Very strong smell. My guess is they connected this hose to the vapor line from the tank, and whenever the engine is running, it is pulling full engine vacuum on the TANK!

Do ya think I've found the cause for this thing getting 14 mpg best? The engine is forcing evaporation of the fuel in the tank constantly, and burning that evaporated fuel! No problem for the tank, as the fill cap will allow air into the tank to it's usual limited amount. Or, under 20 inches of vacuum, maybe gas evaporates at such a rate that NO air enters the tank to speak of, or very little.

What do you guys think of this find? What would you do? Remember, the canister is gone, it's solenoids are gone, wiring to them nowhere to be seen, without tracing back to PCM, nylon vacuum tubes plugged and taped-over. Thanks fer readin'! imp

 

[imp]

Are you looking for a close on command or open on command?

Open, and I might have found one, see post #4.

 

[General karthief]

I believe you have found the purge valve.
Did you ever look behind the right fender splash shield for the charcoal canister?

 

[jrichker]

The original hose had a splice in it about midway. This is because the connection on the lower intake manifold is larger than the connection on the solenoid vent valve.

The solenoid vent valve red wire is always hot when the ignition switch is in the Run position. The computer supplies a ground to complete the circuit. This true for all solenoids, relays and actuators; it is called current sink technology. There is a common power buss that provides power to the computer, actuators, injectors, control relays for the fuel pump and A/C

The following are diagrams courtesy of Tmoss & Stang&2birds

Fuel, alternator, A/C and ignition wiring

The engine mounted sensors are fed by the +5 volt power for the computer's internal circuitry. The O2 sensors generate a small voltage by converting heated oxygen into electrical energy. The MAF provides operating voltage to the sensor circuit from the 12 volts on the MAF heater element.

Fuel injector wiring harness sensors for a 5.0 mustang

[/b]

 

[imp]

I believe you have found the purge valve.
Did you ever look behind the right fender splash shield for the charcoal canister?

The canister is not there. The vacuum connections lie there plugged and taped up. The solenoid is gone, aside from the one miscreant located at the firewall. Was the canister and it's connections not located at the right-front fender area? imp

 

[imp]

The original hose had a splice in it about midway. This is because the connection on the lower intake manifold is larger than the connection on the solenoid vent valve.

The solenoid vent valve red wire is always hot when the ignition switch is in the Run position. The computer supplies a ground to complete the circuit. This true for all solenoids, relays and actuators; it is called current sink technology. There is a common power buss that provides power to the computer, actuators, injectors, control relays for the fuel pump and A/C

The hose connections are both 1/4-inch I.D., the same. Connection is made at the upper manifold underside, where there are 2 connections, the larger being the big "Tee" connection for P.B.

I see that I must determine two things, and must thank you for reminding me that the solenoid may indeed be turned OFF by the PCM after the engine starts, or whenever, and that it has not been re-wired "always-on". This can be easily checked at the sol. ground wire; if it's grounded with key off, this would be bad.

The other thing is, where is the feed hose to the solenoid originating from. Another imponderable is the 3/8-ich OD black nylon tube lying at the R.H. corner of the engine compartment, coming up out of the fender well, open and smelling of gasoline; is it the original tank vent line which connected to the canister? imp

 

[jrichker]

The hose connections are both 1/4-inch I.D., the same. Connection is made at the upper manifold underside, where there are 2 connections, the larger being the big "Tee" connection for P.B.

I see that I must determine two things, and must thank you for reminding me that the solenoid may indeed be turned OFF by the PCM after the engine starts, or whenever, and that it has not been re-wired "always-on". This can be easily checked at the sol. ground wire; if it's grounded with key off, this would be bad.

The other thing is, where is the feed hose to the solenoid originating from. Another imponderable is the 3/8-ich OD black nylon tube lying at the R.H. corner of the engine compartment, coming up out of the fender well, open and smelling of gasoline; is it the original tank vent line which connected to the canister? imp

I think that the size of the hose coming from the upper intake manifold may vary with the year the manifold was manufactured and the make and model of the manifold. The 89 I have used a splice about midway to accommodate the different hose sizes.

 

[General karthief]

The canister is not there. The vacuum connections lie there plugged and taped up. The solenoid is gone, aside from the one miscreant located at the firewall. Was the canister and it's connections not located at the right-front fender area? imp

That looks like the purge valve in the pic. No the canister is not in the same place as the fox cars

 

[imp]

I think that the size of the hose coming from the upper intake manifold may vary with the year the manifold was manufactured and the make and model of the manifold. The 89 I have used a splice about midway to accommodate the different hose sizes.

Surprise! Look at the pic below, which is what I've been going by, out of the Ford Shop Manual:

Canister shown at Right Hand Front of eng. compartment, right where I found the 3/8 inch nylon tube coming from within the fender apron, open, stank of gas. Why the hell would the Purge Valve be located on my car's firewall, high up, almost hood-line, when this drawing shows it clearly hanging on the canister, which ain't there. So, I ripped out the inner splash shield, with those frigging plastic push pins I hate, located where you can't access them with a tool. Almost an hour getting that shield out. Lo and behold: there's the CANISTER!

Right up where Ford says it is when 3.8L equipped, high up inside rear of fender, as the drawing for 3.8L shows:

First, I cussed, then went to check the VIN: it's a "T" eng. VIN, 5.0L. I couldn't imagine some yokel swapping out a 3.8 for a 5.0, and getting all the harnessing to look stock. So, Ford pulled a fast one. Drawing above shows purge valve attached to a bracket. No way on 5.0, so they stuck it down in a convenient hole as I showed in above post.

So, the nylon tube is fresh air IN to the canister. Why does it stink of gas? Do canisters get bad, need replacing? Know very little about them.

What do you guys think of this?? imp

 

[jrichker]

Canisters have at least 2 failure modes:
1.) They get full of liquid gasoline and quit working.
2,) The plastic case crack or breaks, creating a leak.

 

[General karthief]

In the other post when you were going on about not having a purge canister I told you where it was.
Old people, they never listen!

 

[imp]

In the other post when you were going on about not having a purge canister I told you where it was.
Old people, they never listen!

Okay, Okay, but why is it located as per V-6? Oh, and being old ain't the same as feeling old, which I don't. imp

EDIT: Oh, again. you never asked me why I was seeking to obtain a solenoid valve. Young people: no less forgetful.

 

[General karthief]

Okay, Okay, but why is it located as per V-6? Oh, and being old ain't the same as feeling old, which I don't. imp

EDIT: Oh, again. you never asked me why I was seeking to obtain a solenoid valve. Young people: no less forgetful.

Oh yea there old man, what do you need a solenoid for anyway? Try'n to regulate somptin?

 

[imp]

Oh yea there old man, what do you need a solenoid for anyway? Try'n to regulate somptin?

As I've mentioned, (you've likely forgotten, being overworked and all), a now & then condition, hot eng. only, and only if within 15 minutes or so of shut-down, start-up results in tach going up to ~ 1000, then starts dropping, around 500 it bumps up a bit, then drops again, might die maybe half the time, otherwise, it straightens out to normal. If I catch it quickly, apply throttle a bit, it straightens right out. This scenario went away for about a month, I figgered a fluke, then came back, happens maybe 1 out of 5 hot starts, other times perfectly smooth and normal.

Yeah, yeah, as mentioned, eng. has the brand-new T.B. with all it's goodies, off my spare '95 5.0. That add did nothing to affect the "hunting" if you want to call it that (I wouldn't).

Here's the "find": Pulled car into shop, hot, waited about 10 minutes (how long it took her to come out), I had fuel pressure gauge attached, had wife crank, eng. immediately fired up, started to drop down below normal idle speed. Saw fuel pressure immediately drop from a bit under 40 psi cranking, to about 30 running. (Brand-new pressure regulator). Obviously, eng. vacuum yanked upwards on it's diaphragm, dumping some additional fuel to return line, dropping pressure.

Pulled vacuum hose off regulator, had her start again, voila! Eng. speed immediately jumped to ~ 1100, held there a few seconds, then slowly dropped to normal idle speed, smooth as could be. Pressure cranking ~ 30 psi, after start-up, same. Since the real cause of this anomaly is elusive, but I've found a "fix", can you figger out what the solenoid if for? imp

 

[General karthief]

Regulate your regulator?

 

[imp]

Regulate your regulator?

Sure, only at start-up, with a solid-state adjustable time-delay relay. imp