1985 Ford F150 pick up truck 4.9 litre engine emission repairs

[Don Jr.]

Hi, Going to start a post on hopefully sorting out the mess under the hood on this project. It is a feedback system that has been butchered to make it run better but have too many hoses and wires disconnected. I have a pre 1985 Carter YFA non feed back 1 bbl carb. I rebuilt yesterday. Found several things that prevented it to work properly. I ordered a choke stove kit today to conduct heat up a pipe to enter the choke housing to assist opening up the butterfly. Last owner just hung a copper tube hoping heat will enter tube and assist choke. That is being addressed. While I had the carb off I decided to remove the EGR housing that has a gasket that sits between the intake manifold and the lower face of the housing. Could not buy one so purchased a sheet of Fel Ramic material that will hold up to the heat generated . Made a gasket today. New gasket on left of photo factory one on the left. I found the EGR valve itself is shot as the pintle does not seat and leaks when closed. Previous owner also left vacuum hose on it which is a dead leak too. Previous owner used a piece of copper tubing and flattened it out and covered the 2 holes that the EGR uses. Another cob job. I am not planning to replace the EGR but have a question about which holes to cover.I would just bolt EGR back with blocking plate and cap vacuum line to it.  I see the Air pump feeds the assembly. If I just block both holes in the housing I assume the air pump will just try and supply air to assembly or will it bypass and let the air escape somewhere? . Probably not a good situation. Have been told Cat need this air to keep cat cool during operation. I located a Factory book on engine and an learning system connections. My hope is to eventually replace the feedback distributor as the timing of the engine effects engine. trying to repair a section at a time. Any thiughts on the above issue? Thanks.

[ABear]

Man those were dirt ugly days for emission systems..

 

Air pump was added mainly to help introduce more oxygen into the cat, which in turn helps the catalyst in the cats operate at higher more efficient temps which reduces the emissions. Side benefit was it also "diluted" emissions before exiting the tail pipe making everyone much happier.

 

Air pump typically has a excess air dump valve located on or near the pump (often vacuum operated), but without things properly connected and working as designed (like blocking off the airpump output) you may end up with unwanted air dump noises all the time through the valve assembly.. If you are going for the "emissions parts are in place type of route for looks" you might want to leave the air pump output open to the air (IE don't block it) by discretely hiding the output hose open ended.

 

But all of this sort of depends on where the air is injected on what else it may affect. Some injected air at the exhaust manifolds, some at the cats, some at both.. Factory manuals should be most helpful to figure this mess out.

[rocketraider]

A lot of Ford engines from that era have backpressure EGR valves. Disabling it or even opening up exhaust restriction can make them do hateful things. Sixes seem to tolerate it better than the V8s.

 

EEC-IV (think it was IV by that time) was the beginning of too many engine parameters and inputs being monitored, with every last one of them capable of creating drivability problems and nuisance alarms via the CEL.

[Don Jr.]

Yes I agree. Last owner attempted to knock out anything they thought was bad. I rebuilt the carb. which was a mess. It is a pre feedback carb. which is good. Many dangling hoses and. wires to be either eliminated or made operational again. I found the EGR valve not working and the pintle is leaking with the valve closed. Previous owner hammered a copper pipe flat and blocked the 2 hole that make the valve operational. Will make a new gasket to fully block both holes and just bolt the  EGR back in place. Put a small steel ball,in the line that supplies vacuum to it.I looked over the inlet pipe from the air pump and the passage way is  separate from  the EGR system so I believe the air will just pass thru the housing and on to the exhaust pipe. I am just tying to understand which hoses and items to  use and block off. Will investigate an aftermarket GM HEI replacement distributor to replace the factory feedback one in there now. I understand if I do these modifications I can disconnect the computer under the dash and truck should run better. Have a few factory manuals I am going over. Need to understand whole EECV-4 system before I just remove things. A miracle it ran well enough to drive it 5 miles to my place to get repaired considering all the jumpered and missing components. Thanks for any input on this.

[ABear]

Not sure why you would use a GM HEI distributor on a Ford engine or even if it would fit/work..

 

You can get aftermarket drop in electronic ignition systems like Accel, Mallory and others which use conventional coils and allows you to put the coil in a cooler out of the way place than on top of the distributor. But in doing so you are now 100% deleting the OEM computer system and running the engine like it was 1970s..

 

In this case, you will have eliminated the cat system, EGR system and the air pump system..

 

The early EEC systems as you have can be fussy when they don't work, but they also can work well if everything is setup correctly as it came from factory..

 

Primary issue with EEC systems was the Thinfilm ignition system, there were two versions, one had the ignition module mounted on the distributor and the other the ignition module was mounted off the the engine on firewall or fender.. The distributor mounted version tended to be more problematical due to engine heat.

 

But in both cases the worst issue was grounds, as in bad grounds throughout the entire wiring harness..

 

If your State has emission requirements for that age, you will need that stuff not only present but working.

[Frank DuVal]

First, I do not care what the parts books (OK, online parts houses😁) call it, it is a 300 Cubic Inch Six Cylinder!🤣 🤬   Back then only the weird foreign cars went by them metric sizes of displacement. Ford had 300, 302, 351, 460.....😉

 

A GM HEI would have the correct advance curve for this engine? Not to mention diameter, length and gear...

 

 

EGR takes some exhaust "air" and introduces it into the combustion chamber to keep the burning temperature at or below 2500°F (IIRC). 

 

The air pump is to introduce real air into the exhaust system to make sure there is oxygen for the catalytic converter, and to aid in converting CO to CO₂

 

They are separate systems with separate goals. At least that's how I see them. They do have to work together to keep emissions low. It's a balance of all parts (EGR, AIR, carburetor, ignition, etc) to achieve a running driveable vehicle. 

 

As I mentioned in the other thread, introducing air into the exhaust at the wrong time will split the muffler....😮  This is why there are anti-backfire valves (go by other names too).

 

I have fixed many choke air paths on vehicles with these hot air systems (usually Carter, but others too) with steel tubing (choose size appropriate). I drill into the exhaust manifold to open the hole just enough to hammer a new tube into the existing tube inside the manifold ( no need to make leaks) and bend it to meet the choke housing. Put the brass nut on the tube and make a flare, screw it together. Sometimes there is an "inlet" to the manifold stove that also needs to be remade, usually goes to air filter assembly. This is a VERY common failure on these systems.👍

 

Edited August 20 by Frank DuVal (see edit history)

[Don Jr.]

Thanks for the update on this. Yes I prefer to call it a 300 cubic inch motor and will do so from here on out. Agree with balance of EGR and air pump duties. Not trying to eliminate systems but correct any factory blunders. Trying to get the truck running enough to get it inspected and then approach the pitfalls it has. I am missing enough vacuum hoses and rerouted ones to scratch my head as to what goes where. There is a label on the radiator support with a routing diagram I am trying to follow. As I said previous owner cobbled up anything he thought he could bypass. It has a non feedback carb.on the truck now so going to stick with that for now as others have said. Do not know how it will react with rest of system. Believe I have the factory distributor still in it. Will check that out after I get the carb. and EGR air pump mess sorted out. Seeing I am missing plastic delay valves too. Trying to determine what I need where. Understand color coded as to amount of delay each accomplishes. Started out with a shaking clutch issue when purchased and got that resolved. New clutch assembly,rear main seal replacement,resurfaced flywheel,new transmission mount,correct transmission fluid ( was low and wrong ) new rear end fluid ( again low and wrong ). So trying to sort out under hood issues. Engine has great oil pressure and compression. Appreciate input from forum. Thanks.

[Littlestown Mike]

Cobbled and "re-engineered" emissions systems make for nightmares.  You have set yourself a difficult task---If you do not appreciate the beauty of electronic fuel injection, you soon will.  It solved a lot of problems that carbs couldn't.

You might benefit from a visit to a local "automotive dismantling and recycling center" ( junkyard)  to see if they have any similar trucks in their inventory.  You might find one that hasn't been too messed with.  Take a Mighty Vac or similar vacuum tool with you to check out the various delay valves--maybe you will find a couple of good ones. The FSM should tell you how to determine if they are good or not.  The color coding is important.
As we are coming in to the Fall car show season, be on the lookout for similar vintage Fords that might serve as models for hose routing.

EEC was a good system and can be diagnosed with an analog ohmmeter.  The procedure is in the FSM---and all over the internet.

Good luck!

 

The good people on fordsix might be able to help.  They have a forum dedicated to the big six and lots of threads on emissions stuff.
 

 

Edited August 20 by Littlestown Mike (see edit history)

[Don Jr.]

Thanks. Will do. We have a truck show around here in the fall and possibly a unmolested model may be there.  I researched replacing the EGR valve. No identification on mine except for a stamped number on bottom of cast iron flange. 28195302. Number means? No reference to it. Looked up application of stock one and of course several variations. Basically a back pressure model or not. So what do I have? Looks like OEM ones all discontinued and stuck with generic ones with several fits all application. Not looking for  precise operation but need correct replacement parts if possible. I am approaching this issue by each section at a time to keep my sanity. Nice solid truck so worth saving it. I remember when I worked at a Ford Dealership many years ago. Emission systems were just starting to appear ( late 1960's early 1970's ). I got stuck going to training classes as older guys wanted no part in it. 2 of my co workers as young men  ( brothers) started in the teens assembling cars in railroad box cars at the local train depot then getting them to our Ford  dealership. Both Ford accomplished  mechanics. They were quite old back then but enjoyed their stories of Henry's flivers. Now I am starting to feel old! Thanks. Will see what I can locate for a replacement valve.

[Bloo]

You can't go partway with EEC-IV. That will never work. Either it goes back stock, or you get rid of it all. It sounds like you might be confusing the air injection system with EGR.

 

EGR was actuated by vacuum on EEC-IV, and there was a solenoid valve. There is a filter under a black plastic cap on the solenoid. It was still paper in 85 I believe. They plug from time to time and needed replacement. Later Fords have a piece of foam in there that doesn't plug. Never mind that for now. There is probably(?) also a backpressure activated valve on the EGR valve that blocks vacuum to the valve unless there is back pressure, which it senses through a silicone hose into the base of the EGR valve. Never mind that for now. The number on the base, assuming a Ford valve, should lead you to the correct Ford valve, or if using an aftermarket valve, should appear in a chart showing you which selective restriction washer(s) that you will put in the aftermarket valve and stake in place with a punch. Never mind that for now. Also there is probably a sensor that tells the computer how far the valve is open. Pintle wear was supposed to set a code. Manufacturing tolerance was a little too much, and these would often set codes incorrectly. Sometimes new sensors had to be ground or welded slightly to meet spec on new EGR valves. Never mind that for now either.

 

As long as the EGR valve is still present, it is imperative that the pintle does not leak. If it leaks, you will never get acceptable idle or driveability. Blocking it fixes that, and it was a common thing to "cardboard" them, temporarily blocking the valve face off to troubleshoot back in the day. An exhaust analyzer tells the story quick if it is not obvious from listening to the engine that you have made a huge difference. It's usually obvious. The cardboard only lasts long enough to test. Permanent blocking also fixes that, but, legal issues aside, does not fix the problems, because an engine with EGR needs more timing while not under hard acceleration than an engine without, and the timing map is in the computer. Attempting to retard the timing to fix this would leave you with retarded timing at full throttle and no power. That is assuming the electronic timing is even still working, and it probably isn't considering the other modifications that have been made.

 

Air injection is a separate thing. It was controlled by a couple of solenoids called "TAB" and "TAD" and had nothing to do with EGR. Well nothing other than the fact that EEC-IV is an all or nothing system.

 

You'll drive yourself crazy trying to run part of an EEC-IV system like this. It doesn't work. Worse, EEC-IV was never great when paired with a carburetor. On the other hand, EEC-IV with fuel injection is excellent. That's why Ford was such an early adopter of fuel injection. My advice? Sell it and get one slightly newer with fuel injection. The difference is night and day.

 

You have 2 choices here, You can 1) put it back all to original, feedback carb and all, and then start the troubleshooting process of the EEC-IV system, or you can 2) get rid of the whole EEC-IV system. Option 1 is going to be an uphill battle, and option 2 is only valid if you can get away with it in the jurisdiction you live in and it will still be a bit of work.

 

I am going out on a limb and assuming that the "HEI" referred to is an aftermarket distributor meant to fit the 300. That might be a good way forward for you depending on where you live. You might need to recurve it. The carburetor, depending on what it was originally jetted for may need some rework as well. You are currently on an expensive and frustrating path. Good luck whatever you do.

 

Edited August 20 by Bloo (see edit history)

[LARRYCAROL]

You mentioned emissions testing, does your state require testing of vehicle that old? Here in NJ it is not required. That’s with or without antique plates. 

[TerryB]

In PA it’s 1975 and newer if you have a regular registration.  No emissions for antique registration.

[Don Jr.]

Checked with my inspector. Not checked for emission. He said he is supposed to look for all the components that came with truck but really does not look that deep so it will pass. I found out the EGR valve is leaking when you pull a vacuum on it so it is shot. Looking up correct one on line and have a number for OEM that is obsolete so aftermarket it is but they are mostly fits all so leary of proper operation on them. Need to determine if mine has the bleedback style or not.. And yes I believe air pump components are intact and will check for correct operation of each part. Would like to get that working again and check all other components that work with it. So yes going with pre feedback Carter carb already rebuilt and get the GM HEI distributor after I hear the truck run after all the work I have done to it. I am leary of the Chinese ones as I agree timing curve issues. I see one for $450.00 with curve adjusted for your application as opposed to the Amazon Chinese one for $99.00. Will contact company and see what they reccomend as far as their units. This truck is for shop duties and loan out to son on his projects so not front line car everyday. Worked over spare tire carrier today as that is not correct. Previous owner put on a Class 3 hitch and right side bracket interferes with bottom arm of carrier when you bolt it up.. Will find a work around for that.  Waiting on the choke stove for install. Supposed to be in on Thursday. Cleaning up right side of motor while EGR and carb are out. Valve cover leak made a mess. Will pull that and clean it up paint it and reinstall with a new gasket. Thanks.

 

[Frank DuVal]

8 hours ago, Don Jr. said:

Checked with my inspector. Not checked for emission. He said he is supposed to look for all the components that came with truck but really does not look that deep so it will pass.

Ah, just like Virginia except for 5 or so counties bordering I-95 up here, and then at 25 years of age it goes away up here! Just has to "look" the part, as that is part of the yearly safety inspection.(?)

 

8 hours ago, Don Jr. said:

I found out the EGR valve is leaking when you pull a vacuum on it so it is shot.

 

So you are saying the internal diaphragm is leaking, not the pintle. Now, I have condemned parts because of this when I discovered some items have controlled leaks! Oops. Do you know if this leak might be normal?🤔

[Motorpirate]

Bear in mind, those aluminum EGR housings used to burn out internally between the passages.

This would mimic a non sealing pintle on the EGR valve.

 

[Littlestown Mike]

One more thought about heat for the choke.... In addition to the stove that brings heat from the exhaust manifold, does your carb have the electric heater inside the spring cap?  If not, I think adding an electrically heated cap will be the ultimate answer to choke heat.

[Don Jr.]

Hi checking on the calibrated leak shall we say on the EGR valve. Local parts place is ordering one in to compare. And there is no heating element on the inside of the cover. Just a spring. I have been going over the entire setup to understand how the EECV-4 system worked. I inventoried all the components present and their correct connections.. Found the purge canister hose to feedback carb tucked near frame open, Connector for idle air control and throttle position sensor tucked in harness too. Missing 2 calibrated plastic delay valves in the hose set up. And EGR valve had a blocker plate installed across the face.. Will attempt to see if engine runs with the rebuilt pre feedback carb. And if so how good. 

[Don Jr.]

Hi, all put back together.Ran good on warm up. New choke stove kit works well and butterfly opens up well too. Road tested truck. Has a surge when accelerating in all gears. Looks like distributor is in a default mode. Working thru this issue next. May need the GM HEI distributor to correct this problem.

[Littlestown Mike]

Why the fascination with GM HEI?
Good discussion here---  https://fordsix.com/threads/do-we-really-need-a-modern-ignition.79919/#post-619083

[EmTee]

11 hours ago, Don Jr. said:

Has a surge when accelerating in all gears.

Lean mixture?

[Frank DuVal]

1 hour ago, EmTee said:

Lean mixture?

That is where I would go. Make sure carburetor is sealing to the intake manifold and all vacuum lines off the manifold go somewhere or capped off.

[Hemi Joel]

That was a transition/development era for pollution control equipment. It didn't work right when it was new. That engine family began in the '60s. I would get rid of any part or piece that had anything to do with the pollution control equipment and bolt on the stuff from a pre-emmissions vehicle. It will run beautifully and never give you any grief.

[Don Jr.]

Hi, All new gaskets around carb.  and manifold.  New vacuum hoses where needed.. Truck is recent purchase flat bedded home. Went thru clutch and transmission to get that right. Started on engine issues. Identified pre EEC - IV carb. on it and rebuilt it. Wrong ERG valve but blocked at the moment. Quick road test gives the surge so assume with emission light on system not working and distributor is in default mode. I agree the HEI is a quick  cure but all my other projects have point based ignition with no issues. Finishing up other issues for inspection get that done then revisit the feedback system. Been a learning curve on it's operation. Did the original system ever work correctly?

[Frank DuVal]

There is an emissions light? 🤔 I've never seen mine on. Do you need pictures under the hood of how it looked originally? Mine has no outward disconnects. I have taken more pictures.

[Don Jr.]

Hi, Thanks for that photo. I put the hoses and wires back to see if it would run better. No go. With the wrong  EGR valve blocked off and the feedback carb not there good reason light is on. I am next going to unplug the Sprout line from the distributor and see if the truck runs any better. ECM will go in default timing mode if not already there now. Guess it will set itself to 10 degrees BTDC and stay there. Looking like I will need the distributor swap. Tried looking up amount of dwell the feedback distributor gets from the ECM so I can get another distributor ( HEI or point style ) and get it curved to the truck as new distributor will have a vacuum advance and mechanical  advance. No published info on it. Am digging to see what point style distributor used for their advance curves. With a new distributor will have it set then try the road test. Thanks.

[Bloo]

EEC-IV would have had a 3 dimensional map for timing. They never would have published it (proprietary), you can't copy it exactly with 2-dimensional centrifugal/mechanical advance, and you wouldn't want it anyway because you no longer have EGR. EGR changes the part throttle timing requirements too much.

 

If the new distributor is made and marketed for 300 Ford, there is at least some chance they will give you a reasonable curve that is sort of close. If it does, great, but I wouldn't count on it. Too many aftermarket distributors come with a curve more appropriate for bracket racing than anything else. If you copy the curve of some other Ford 300 distributor, I'd choose one that is pre-1968, so probably 1966-67 would be good.

 

What SHOULD happen is that the initial timing plus the centrifugal advance (in other words the timing curve with with the vacuum hose disconnected) should be set up for maximum power through the RPM range. The vacuum adds the extra timing that makes it run OK (and get reasonable fuel economy) at part throttle. Despite it's curve, it really behaves more like a switch between full throttle and cruise. How many degrees vacuum advance you can get away without pinging or destructive roughness is probably limited by the engine at some particular RPM. It is what it is. If you need to limit total vacuum advance, and assuming this is GM coil-in-cap HEI, the aftermarket makes stop kits to help with that. You probably wont be able to just shove an Allen wrench in it like a Ford. Connect the vacuum hose to the "ported vacuum" port on the carburetor. There should be vacuum with the throttle open and none with the throttle shut.

 

Often on trucks the advance curves are shorter and lazier than they would be on a car. You may run into this looking at 60s period advance curves. This is to make absolutely sure that a truck does not have too much timing for the conditions and possible bad fuel, etc. This compromises horsepower and fuel economy somewhat compared to a car, but makes sure you don't ping the engine to death when hauling a bunch of concrete block up a mountain pass.

 

Good luck.

 

Edited August 27 by Bloo (see edit history)

[Don Jr.]

Thank you, That is the info I was looking for. Could not believe you pop an aftermarket GM HEI unit in and magically  done. Might run but how efficiently. I can send these new units out and get them re curved but still questioning  the off shore quality for $100.00 dollars. I have a Hudson Mallory dual point distributor I modified to fit a 1949 Ford 226 in line engine in our 2 man race car. Had it overhauled by a known distributor guy ( now passed away). Installed it in the race car and it either fired up erratically or just threw fire out of the 2 1 bbl. carbs.  Did not make sense. Called him back to discuss the issue but he passed a month prior. So located a shop that does distributor and magneto work, sent it to them. They had trouble figuring what was wrong. It turned out the new breaker plate made to accept more modern points was made a bit off and the were out of sync. With the new plate it fires right up. Lesson learned get what you pay for hopefully. Will discuss the 300 engine with distributor guy and see what he thinks. Thanks again.