Emissions vacuum lines
New User
Joined: Mar 2001
Posts: 12
Likes: 0
Emissions vacuum lines
I just recently bought an '81 F150, 300 six, 4 speed manual. As with anything you buy used, I'm getting familiar with what's under the hood. I noticed before buying it that all of the emissions vacuum lines have been disconnected and plugged. I didn't realize what a puzzle it would be to determine what should be connected to what! The "map" that is under the hood is greek to me, since I don't know what the abbreviations are for, and I'm not the most gifted mechanic in the world. How would a guy like me find out how to get this stuff reconnected? I not only think it would be best to have it right for environmental reasons, I expect it'll probably run better. (It idles a little rough, and I wouldn't be surprised if there's a connection.) Can anyone out there shed a little light on this for me? I'm new to Fords, and I want to get off to a good start with this cute stepside. Thanks in advance.
Freshman User
Joined: Oct 2000
Posts: 34
Likes: 0
Emissions vacuum lines
Scott,
There should be a sticker in the engine compartment showing the routing of the emission vacuum lines. It should have colors of hoses and components they are connected to. MAP stands for the Manifold Absolute Pressure sensor. Mine is located above the passenger side fender just aft of the battery. It should be connected directly to intake manifold vacuum with one hose and it should have 2 or three wires coming off of it that go to the computer telling it how to control the engine based on its vacuum. You may also see other abbreviations for solenoids like TAD (Thermactor Air Diverter) and TAB (Thermactor Air Bypass). These control vacuum to the ACV (Air Control Valve) which is downstream of your smog/air pump (if you have one) that determine where air is injected into the exhaust stream (Exhaust Manifold or Catalytic Converter) to scavenge unburned hydrocarbons. EGR stands for the Exhaust Gas Recirculation valve. On mine there is a solenoid that controls vacuum to this valve whose function is to admit exhaust gases into the fuel/air mixture for the purpose of reducing combustion temps hence reducing formation of NOX which is another pollution concern. A/CL stands for Air Cleaner. CPRV stands for the Charcoal Canister Valve. This solenoid valve exposes the charcoal canister that absorbs gas fumes from the tank(s) and the carburetor bowl (SV-CBV Solenoid Valve Carburetor Bowl Vent) to engine vacuum when the truck is running to burn them off thus minimizing pollution that way. There is usually a A/CL BI MET (bimetallic sensor) that controls vacuum to a diverting valve when engine compartment temp is low. If it is cold in there, the engine inlet air is redirected to a shroud around the exhaust manifold so the engine warms up faster and the fuel gets atomized better in warm air compared to cold. Sometimes there is even a VRDV (Vacuum delay Valve) between the A/CL BI MET and the A/CL diverting valve. This delays the redirection of the hot air from the exhaust shroud to normal cold air intake. PCV stands for the Positive Crankcase Ventilation valve. It allows intake manifold vacuum to suck blow-by gases that get around the piston rings from the crankcase back into the cylinders to be burned thus keeping your oil cleaner and preventing your crankcase from being pressurized and blowing out all your gaskets (oil pan, crank shaft seals etc.)
These are just some of the emissions gizmos on my '84 F150. Yours is probably different but not by much.
If you can't find the emissions sticker, I can probably get you a copy and send it to you if you get me your year, model, engine, and calibration code and e-mail address. The calib code on mine is on a sticker on the forward end of the valve cover. For my '84 it is 4-51D-R01. Yours should be similar with the first number being the last digit of the year yours was made.
Hope this helps. Good luck.
Will
'84 F150
YFA F/B
SROD
"Ex" => Bone Stock
There should be a sticker in the engine compartment showing the routing of the emission vacuum lines. It should have colors of hoses and components they are connected to. MAP stands for the Manifold Absolute Pressure sensor. Mine is located above the passenger side fender just aft of the battery. It should be connected directly to intake manifold vacuum with one hose and it should have 2 or three wires coming off of it that go to the computer telling it how to control the engine based on its vacuum. You may also see other abbreviations for solenoids like TAD (Thermactor Air Diverter) and TAB (Thermactor Air Bypass). These control vacuum to the ACV (Air Control Valve) which is downstream of your smog/air pump (if you have one) that determine where air is injected into the exhaust stream (Exhaust Manifold or Catalytic Converter) to scavenge unburned hydrocarbons. EGR stands for the Exhaust Gas Recirculation valve. On mine there is a solenoid that controls vacuum to this valve whose function is to admit exhaust gases into the fuel/air mixture for the purpose of reducing combustion temps hence reducing formation of NOX which is another pollution concern. A/CL stands for Air Cleaner. CPRV stands for the Charcoal Canister Valve. This solenoid valve exposes the charcoal canister that absorbs gas fumes from the tank(s) and the carburetor bowl (SV-CBV Solenoid Valve Carburetor Bowl Vent) to engine vacuum when the truck is running to burn them off thus minimizing pollution that way. There is usually a A/CL BI MET (bimetallic sensor) that controls vacuum to a diverting valve when engine compartment temp is low. If it is cold in there, the engine inlet air is redirected to a shroud around the exhaust manifold so the engine warms up faster and the fuel gets atomized better in warm air compared to cold. Sometimes there is even a VRDV (Vacuum delay Valve) between the A/CL BI MET and the A/CL diverting valve. This delays the redirection of the hot air from the exhaust shroud to normal cold air intake. PCV stands for the Positive Crankcase Ventilation valve. It allows intake manifold vacuum to suck blow-by gases that get around the piston rings from the crankcase back into the cylinders to be burned thus keeping your oil cleaner and preventing your crankcase from being pressurized and blowing out all your gaskets (oil pan, crank shaft seals etc.)
These are just some of the emissions gizmos on my '84 F150. Yours is probably different but not by much.
If you can't find the emissions sticker, I can probably get you a copy and send it to you if you get me your year, model, engine, and calibration code and e-mail address. The calib code on mine is on a sticker on the forward end of the valve cover. For my '84 it is 4-51D-R01. Yours should be similar with the first number being the last digit of the year yours was made.
Hope this helps. Good luck.
Will
'84 F150
YFA F/B
SROD
"Ex" => Bone Stock
Posting Guru
Joined: Jun 1999
Posts: 1,083
Likes: 1
Emissions vacuum lines
Or, you could befriend someone with similar year truck/engine/tranny and have them come over one evening or Saturday. Pop the hoods, and your favorite beverage, and duplicate the lines/routing on the other truck under your own hood. If I still had my 81, I'd volunteer it as a demo but it went to the big scrapyard in sky several years ago.
New User
Joined: Mar 2001
Posts: 12
Likes: 0
Emissions vacuum lines
well, I think it sounds great that you want to help do your part for the environment. I think we all should. But my question is, why were they disconnected in the first place? I would guess something happened to cause the previous owner to disconnect them. all of mine is disconnected because the egr valve rotted and fell apart. I think the previous suggestion of finding someone with a truck is your best bet, but if you're stuck, email me, I have a full set of manuals for an 84, which is the same truck I believe. fsmtnbiker(No Email Addresses In Posts!)
Chris
1980 F-250 Described as the "Old, Rusty, brick-on-wheels"
200,000 miles and counting...
clutch- 200,000 miles and counting... and bucking in reverse...
Chris
1980 F-250 Described as the "Old, Rusty, brick-on-wheels"
200,000 miles and counting...
clutch- 200,000 miles and counting... and bucking in reverse...
New User
Joined: Mar 2001
Posts: 12
Likes: 0
Emissions vacuum lines
I can't thank you enough for all the information. My '81 doesn't have a computer, which is one of the reasons I chose this model year. Some of the stuff you mentioned that is on your '84 isn't on mine, but the information you provided will help. Part of the puzzle that I'm trying to solve with my truck, is that a previous owner "worked it over" under the hood, so the valve cover doesn't have the sticker you mentioned, and the factory sticker showing the routing of emission hoses is a little cryptic. Your explanation of the abbreviations should help, though. Once again, I can't thank you enough.
New User
Joined: Mar 2001
Posts: 12
Likes: 0
Emissions vacuum lines
Your idea of finding another '81 that is "anatomically correct" is a good one. I suppose finding one of those in the Seattle area shouldn't be too hard. Thanks for your response.
Trending Topics
New User
Joined: Mar 2001
Posts: 12
Likes: 0
Emissions vacuum lines
I don't know if the previous owner was trying to compensate for a faulty part, as you suggest, or if they were trying to get back to the "good old days", when there weren't any emissions devices. The main thing I'm trying to accomplish is to do my best to make the truck run "correctly", regarding both emissions, and driveability. Since everything has been plugged, I don't have a functional heat riser, and the EGR valve is plugged, not to mention everything else that is related to emissions. Though it doesn't get as cold in Seattle as it does in say, Minnesota, it would help to have the heat riser working on cold mornings. With the information that I've received from a previous post, and with the suggestion of finding another '81 that is complete, I think I'm on the right track now. Thanks for your response.
Freshman User
Joined: Oct 2000
Posts: 34
Likes: 0
Emissions vacuum lines
Scott,
I've got a 1984 Canadian-made F-150 that has a feedback carb. I don't think it was made to CA emissions standards since I bought it in 1986 in upstate NY but it has its share of emissions crap (smog pump and the whole nine yards). I live in CA now so I have to get it smogged every other year. Over the past 6 years it has failed twice, both for EGR related problems. The first time the valve needed to be replaced and the second time the computer just wasn't signaling the EGR vacuum control solenoid to open when it should. I still haven't figured that one out by the way but I just routed the ported vacuum signal from below the throttle plate straight to the EGR and it passed on the second try. By the way, if there is any emissions gurus out there that might know why this would happen, I am open to suggestions. All the wiring has continuity and there are no codes stored telling me why the computer won't tell the solenoid to pass vacuum to the EGR. It seems more restrictive the way I have it now anyway since the EGR gets vacuum and opens whenever the throttle is off its shut seat instead of waiting for the engine to warm up when the ECU normally signals the solenoid to send vacuum to the valve. The only thing that would suffer that I can see would be drivability from the way I have it now and living in Southern CA, cold startups aren't too much of a problem. Oh well, enough rambling. Later.
Will
'84 F150
YFA F/B
SROD
"Ex" => Bone Stock
I've got a 1984 Canadian-made F-150 that has a feedback carb. I don't think it was made to CA emissions standards since I bought it in 1986 in upstate NY but it has its share of emissions crap (smog pump and the whole nine yards). I live in CA now so I have to get it smogged every other year. Over the past 6 years it has failed twice, both for EGR related problems. The first time the valve needed to be replaced and the second time the computer just wasn't signaling the EGR vacuum control solenoid to open when it should. I still haven't figured that one out by the way but I just routed the ported vacuum signal from below the throttle plate straight to the EGR and it passed on the second try. By the way, if there is any emissions gurus out there that might know why this would happen, I am open to suggestions. All the wiring has continuity and there are no codes stored telling me why the computer won't tell the solenoid to pass vacuum to the EGR. It seems more restrictive the way I have it now anyway since the EGR gets vacuum and opens whenever the throttle is off its shut seat instead of waiting for the engine to warm up when the ECU normally signals the solenoid to send vacuum to the valve. The only thing that would suffer that I can see would be drivability from the way I have it now and living in Southern CA, cold startups aren't too much of a problem. Oh well, enough rambling. Later.
Will
'84 F150
YFA F/B
SROD
"Ex" => Bone Stock
New User
Joined: Mar 2001
Posts: 12
Likes: 0
Emissions vacuum lines
The problem you're having with your EGR valve is similar to one I've had with a Suburban I once had. It, too, had all of the emissions stuff torn off, and in putting it back together, I found that, at least with Chevys, the vacuum line was routed through a "Christmas tree", a plastic, multi-ported vacuum device on the thermostat housing. A vacuum source is piped to one of the fittings, and the vacuum is only supplied to the other ports when the temperature of the coolant reaches a certain temperature. There was also another device in the vacuum line from this "Christmas tree" to the EGR, which required the vacuum to reach a certain level before the EGR would open. These two things combined prevented the EGR from opening until the coolant was hot, and then only when the vacuum reached the right level, presumably once you're well up into the RPM range. Up here in the Seattle area, we are also required to pass an emissions test every two years, and that's part of the reason that I'm doing what I am with this project.
By the way, the explanation of the abbreviations on my emissions routing sticker helped, but I'm still at something of a loss to determine where the vacuum lines connect to the source. I'll be spending some time on it this weekend, so I might be able to figure more out then. Thanks again for your help.
'81 F150
4.9, 4spd.
Shorty stepside.
By the way, the explanation of the abbreviations on my emissions routing sticker helped, but I'm still at something of a loss to determine where the vacuum lines connect to the source. I'll be spending some time on it this weekend, so I might be able to figure more out then. Thanks again for your help.
'81 F150
4.9, 4spd.
Shorty stepside.
Thread
Thread Starter
Forum
Replies
Last Post
