I am probably buying an 81 318 fuel injected Chrysler today.

The previous owner wanted to switch to carb years ago and began taking off everything above the intake. That was some time ago, and he never finished. Ive switched a 76 Cordoba from lean burn to carb. It took a new Dizzy, new eddy intake, eddy 625 carb, coil, splug wires, plugs and a box. Plus some vacuum line re-routing/ eliminating. Worked fine.

Since this was a 76 and the 'computer' in the air filter housing only controlled limited items so removing it wasnt a hassle and didnt disrupt any gauges or other systems, and only involved minor wire modifications and only in the engine bay.

Now, I've never owned an 81 chrysler, and it has pieces missing from the intake and up. So, what do I need to convert it? Were 81's still Lean Burn technology, or did they have a more modern ECM that controlled more than just ignition system? If so, is there a ecm somewhere under the hood or in cabin? Did it use sensors on the engine, exhaust and tranny to get info? Will disabling it mess with any other systems besides ignition, and will it affect any accessories or interior gauges/switches?

Basically, if it is different and controls more than the 76 lean burn computer, what all do I need to convert to carb?

Also, if it is better than a 76 lean burn computer, would it be more cost effective, less of a hassle, or just more efficient to just restore the original FI system?

Knowing model and engine size will be a huge help here.

May have just been a lean burn setup that the owner mistakes for fi.

If it was fi, likely a stand alone system, so very similar to changing out a lean burn setup. You'll need to figure out a fuel pump or regulator in addition.

Assuming it was an Imperial, there has got to be somebody on this site that has done the swap. Wait for them to interject. I think the changeover to carb was not real involved IIRC.

There is exactly ONE OEM fuel injected 318 in 1981.

Since you obviously do not know that do not offer up your uninformed opinion.

The 81 EFI system is fairly primitive, your change over will be very similar to the lean b urn conversion you did on the 76.

I'm thinking you would convert it like you would the earlier one; early t cover/mech pump/hughes cam extension/intake/carb/dist.

Yes I said 81 Chrysler on my post, but I forgot to say imperial. And it was definitely fi

Thanks all. I can rewire everything if it's similar to lean burn. Was the computer located in the top hat? Or was it a box somewhere in the cabin, or engine bay?

I just bought the Imperial it is in fantastic condition. I found all of the original fuel injection parts and the Lean burn computer and top hat combo. The guy who owned it passed away and his son said before he began the conversion the fuel injection worked great and the car ran really well. Well I get there and open the hood it looks like all he did was unplug the lean burn computer and took the top hat off and nothing more. I turned the engine over by hand and it rotated nice and smooth. So I'm going to just try and hook the computer and wires back up put some new gas oil spark plugs and coil on and see if it fires up. I'll begin a new thread when I start doing the work because I've never seen this type of setup before and could probably use some advice and pointers. Hopefully I just walked away with a valuable car for cheap. Even the floor pans were in great condition and the carpet too. I also got to keep extra parts that were in the garage including a distributor for a 1969 440 charger and an electronic dizzy as well as in the box nos switches for various things like windows! I also got a full service shop manual for the Imperial

The guy has also got a Shop full of tools and equipment that the grandma is selling off cheap

its your lucky day bro (makes up for the bad ones). I would suggest keeping it in this same thread.

This is the extent of what he removed

Thanks Robert! Even if the motor turns out to be a dud, I'm sure I could rebuild it and still be at less of a cost than the car is worth

The swap is actually more involved than the typical lean burn. the old lean burn is just spark control. In the 81-83 imperials, there is a spark control compute, as well as a fuel control computer. The system is a 'constant flow' vs a typical efi where injectors are just turned on or off. There is the low pressure fuel pump in the tank, plus a high pressure pump on top of the throttle body (the big cylinder in the photo), that constantly puts fuel through the tb but varies its speed based on input from several sensors found on modern cars like 02, speed density, fuel flow meter and fuel temp sensor, among others.

This is an amateur explanation at best, but simply it is much more complex and was so troublesome it was ended after a 3 year run. The factory warranty carb conversions included replacement of the fuel tank, harness modifications and lots more.

What really adds to the trouble here is the digital display gauge cluster and all the fancy options it supported like a mpg readout. So just switching the dizzy, intake, ignition control box, and carb is not good enough if one wants to keep anything but the speedometer working on the dash cluster.

Its definitely doable, I just need to do a lot more research and read everything from the imperilclub.com., a great source of info on these early and unique efi systems. On the other hand, my efi system is complete, and there are mods I can do to eliminate some of the problems it had.. then I could have a plush cruiser. but really I think I'd prob be more happy selling these rare parts to someone else and switch over to carb, and a new cam, some headers and a non lockup converter

the 81 imperials are a cool car.
if i had the $$$ and a really good place to work on them i would put a 3rd gen hemi in one.

before spending much money research what they are worth. new they were 20K+. now not so much.

If you have all the parts, I would try and salvage that EFI system. To me that kind of stuff is cool! Failing that, a carb and a ready to run all-in-one type distributor is super easy to hook up. I'd do an electric fuel pump to make it easy.

Check out the Imperial Owners Club . . .they have lots of information on the fuel injection system and changes to carbs . . .

http://www.imperialclub.com/

Cheers

mark

That looks like the system we called the hydraulic injection system. It was not used on many cars as when I went to the Dodge dealer in 1986 I got some training on it and to be honest I never saw one come in the dealer shop so I never actually worked on one. It was only on certain Chrysler cars and I think only around a year or two. But they said they were not a great EFI system and not many techs out there know much about that system. I actually still have my Mopar training book on that system. My best advise is get rid of it unless you know how to work on it or know a tech who knows alot about it to help you if you have problems. And I would guess parts are hard to find for it if you would ever need any replacement parts. Ron

You won't get it started without the air cleaner on and tight. The ASD just won't let it pump fuel without it all on and tight. The changeover is fairly simple, but more involved than a simple lean burn removal.

I have 2 Imperials an '83 with a Magnum 360/727 and an '82 with the stock efi. The '82 gets insane mileage, rarely under 17 combined and up to 26 straight highway. A lot of that is because of the 2.24 rear. It isn't a complete dog because of the low gearset trans. I had a ton of trouble with vapor lock in the past and haven't had it out since I moved overseas in 2006.

I would try to get it running with the efi. It will hunt rpm a bit, but otherwise they are very smooth and excellent when running right. They are pretty finicky though. The imperial club A12 Mark referenced has a ton of good info including the retrofit manual. You can do it with junkyard parts, but will lose some of the features of the trip computer.

http://www.imperialclub.com/Repair/Year/1981-1983/index.htm

I mentioned the imperial club in my post. I have all their info and tricks, like isolating the asdm from the fender and running it's own seperate ground wire.

Daytona turbo the car already has an electric fuel pump, 2 actually but one gets eliminated in the swap.

383 man yes it's a hydraulic injection system, and also known as a constant flow system.

If I can get it to run right I'll keep it. If not,.the mechanical swap is the easy part, keeping all of my fancy inststrument cluster working properly is the hard part

I *think* most of the stuff will work correctly. The speedo and the odometer do on mine anyway. The guy that did the initial 360 swap on mine put a Mirada tank and sender. I think the gas gauge can be a minor problem if you stick with the original stuff. The trip computer probably won't work too great, but even my stock efi car gets a little squirrely with the fuel gauge and telling me I am getting 99 mpg. You can tell if you review the conversion kit what you need to try to keep it all working right, but you probably won't care about some of it.

My cars are kind of a strange case because the backyard converted car was done up right, while my stock efi car was just kept running for years and got kind of cobbled. I really just bought it for the seats, but it got such good mpg and had cold a/c, so I ended up daily driving it for 3 or 4 years.

Cool, I didn't realize they were constant flow injectors. Sounds like a better version of the EFI system chrysler came out with in 50's. I know there's at least 1 still running with the original efi system.

Ok so I looked closely at my tophat/computer/maf. It says remanufactured. I think all 3 years of this tbi system used the same components, so hopefully this one works on my system. The previous owner may have had problems with the original at some point and got this as a replacement.

Because I've never owned one of these, Im wondering if anyone here knows if this unit is plug and play or if it was some update that chrysler put out to fix tbi issues and if it possibly requires other updated parts. Im going to slap it all together on saturday after I disassemble and clean out all components that have old fuel in them, and see if it will fire up with fresh gas and battery.

Im also going to check my local hardware store for some flat stock foam/rubber gasket material that I can cut to size and replace any old gaskets that may cause a leak. the tophat still has the thick rubber seal on top in good shape, so I think Im ok there. My goal is to eliminate any possible vacuum leaks in the system and clean out any crud/varnish from old gas. That way if I have problems I can eliminate bad gas and vacuum leaks right off the bat

Im still amazed that as smart as chrysler engineers were, why on earth did they put the MAF in the air cleaner??? 1st of all, at that time, most FI cars were still using MAP sensors, but chrysler used some pretty advanced/efficient components for a fi engine in 1981, so with all that engineering going into it, why would they place the majority of these parts in compromising areas, like hard to seal air cleaner assemblies that sat right on top of the engine? Not to mention the ignition control computer sitting in the air cleaner as well getting shook around constantly while the engine was running. And then relying on a screw to ground the power cut of module to the fender.

I guess I really cant talk smack about it, not like Im an engineer nor have I ever designed an FI system, but some things just seem like a no brainer. maybe they were stuck with budget constraints and were forced to modify existing parts instead of building new parts like throttle bodies that would house the MAF, and feul/spark control computers relocated to engine bay or cabin

They may not have known any better. Think about it, just a few years earlier they came out with the lean burn system with the ecu on the air cleaner and by the time this system was being designed those lean burn cars were still running fine.

Got everything cleaned up and assembled. put about 4 gallons of premium fuel and a bottle of seafoam in the tank, The engine turns over nice and strong, and Im getting spark, but not a drop of fuel. I unplugged the asdm and jumped the contact of the large blue wire to the contact of large green wire. I dont know exatly what this does but I read about it on theimperialclub.com. When I turned the key to on I could hear a fuel pump running, couldnt tell which though, still no start. But it was late and I'd had a few beers and was done working on the car for the night.

I think the pump I heard was the control pump in the hsa assembly. I will have to have someone turn the key while I look down the throttle body to see if its even priming. I havent checked out enough of the possible problems yet to make an educated guess, but I think either the pump in the tank isnt working, the duel filters are clogged, or the control pump or entire hsa assembly isnt working right.

When I go back out Ill check everything in that order. Does anyone know if the fuel computer also controls the in tank pump or just control pump?

Ok the in tank pump is working fine. The previous owner had spliced another 3/8 hose with a valve on it to the fuel feed line that feeds the control pump in the hsa assembly. So with the asdm bypassed and the key turned to on position, I opened valve and fuel sprayed out. I tested the voltage to the control pump and it was 6 volts. I know it's a constant flow system and the speed of the control pump is controlled by alternating voltage, but not sure if 6 volts is to low.

What I cannot figure out is if the pump is dead or not getting enough voltage because not one drop of fuel is coming out of the 4 little rails that spray fuel into the throttle bores. I know the rails are fine because I cleaned them out with carb cleaner and they flowed fine.

Well I unhooked the little metal fuel line that goes from the control pump to the fuel injection assembly. Turned the key and after about 2 seconds it starts steadily pouring a small volume of fuel. It's not a dribble but definitely not high pressure. Should be enough pressure to have fuel come out of the rails. After that I hooked everything back up put the lid on the top hat and with the asdm bypassed I turn the key and the car started right up and sounded perfect. It was running off the fuel that had poured out of the feed line to the fuel injection rails when I had it off so it only ran for a little while and then it turned off when it ran out of fuel. So my next step is to take off the fuel injection unit and see why the fuel is getting caught up inside and not coming out the rails. Maybe it has its own pressure requirements before it lets the fuel come out.

But with the amount of fuel that I described that poured out of the feed line to the fuel injection unit, does that sound like the right amount of fuel that should be flowing? Is the control pump possibly dead and that small amount of fuel that came out just just the remainder of the fuel being fed from the tank pump after it pushes its way through the Dead control pump?

Took apart the fuel injection unit again. There are 2 needle and seat valves like in a carburetor fuel bowl. I took them out and opened them manually with my finger, so they aren't frozen up. Looks like there just isn't enough fuel pressure to overcome their spring pressure removed them and reinstalled the fi unit. Car fired up and although it idled high and didn't feel right, it ran and drove.

So it's probably a fuel pressure issue, My next step is to finally buy a fuel pressure tester and see exactly what pressure I'm getting out of the tank pump and the control pump and see where I'm at.

At least I know the engine runs. Can't wait to figure this out and start driving it, the car is incredibly comfortable and was well taken care of

Sorry I can't be much help but I always find it interesting when people get old unusual induction setups running. Keep us updated, it sounds like you are close.

Success, sort of. Taking both needle and seats out floods the car almost immediately. Putting them both in , I get no fuel at all. I took out the needle and seat for the rail with the small sprayers, and left in the needle and seat for the large sprayers.

Car fires right up and runs and drives. It's not as smooth obviously as it could be because the fuel is basically just pouring out of the fuel rail instead of a nice spray pattern. But it works and now it runs and drives. That is until it finally gets flooded then it stops and I have to wait for it to dry or plug the asdm back in and fire up the car and burn up all the fuel that's in the intake then unplug the asdm and bypass it again and then the car fires right back up and drives.. until it floods lol.

This is a decent mickey mouse fix until I can find the cause of my low fuel pressure. Or gather the intake and carb I need for the conversion.

I'm going to get the conversion parts anyways actually, just in case I cant find the parts I need for repairs to the efi.

I'll probably run a switch that connects the green and blue asdm wires and run the switch to the cabin so I can turn it turn off the bypass when I flood, then burn it off, then flip the switch and bypass it again and start it up and drive! It's a temporary mickey mouse fix but it is better than nothing

MY GOD, These cars are insane.

So, I settled with the fact that I would be driving it for a little while in the condition I described above. At peace with that fact, I start doing other things like putting the door panel back on, replacing the fuse for the horn, playing with the gauge cluster fuse (the gauge is fully digital, but looks all scrambled and weird, just another issue to deal with I guess). There is this hissing noise whenever you open the door and the gauge cluster lights up, and continues after the car starts. Well, take out the 4 amp gauge cluster fuse and the hissing goes away. Not sure what the hell that is, but I did notice at least 3 vacuum pods under the dash. So I also replaced the front passenger caliper which was rusted and locked up, bled the brake line, and finally put some under dash wire harness connectors back on their mounts (they were just hanging). I finally installed the under dash cover and now Im tired and I want to enjoy my labor and go for a cruise.. well, a cruise that involves the engine flooding every ten minutes, but whatever I know I just undo my jumper on the asdm and then crank the car and burn up the flooded gas, then re-jumper the asdm. Its worth it after a day of labor.


SO, I get in the car. Apparently an exhaust leak has begun somewhere, cause I can really hear it now. I take the car out from my coltesac, and give it some gas, it hesitates and BAM backfires through intake, so I just take it slow and easy. The driving characteristics begin to change. hard to explain, but it ends up with the car dying.

So I get out and take the jumper off the asdm and plug the asdm back in its connector as usual. I get in the car, turn the key and after a couple seconds it turns on and I sit and wait for it to die. But.... it doesnt die... it keeps running! I was mystified and scared at the same time. Could it really have solved itself??? I shut the hood, and go driving. peppy acceleration, doesnt run smooth but it runs. I drove it all over. It doesnt like hills, but does great on the flat roads.

So apparently the EFI decided its going to work again. I get home and get out to investigate exhaust leak. I opened the hood and within seconds my eyes are burning and crying, I backed up.. then looked under the car.. for a few seconds until my eyes begin to burn and cry again. It was running fatty fat pig rich. Must be because I took the needle and seat out, which was necessary at the time, but now is causing it to run super rich. I also had the o2 unplugged for same reason, to help it run better back when the asdm was shutting everything down, so I plug it back in. I turned the car off and called it a night.

Looks like I now have a running driving imperial with a fuel control computer that has decided it likes all the attention Ive been giving her and will now operate correctly when I turn her on.

So tomorrow, I re-install the needle/seat in the FI unit, and take a look at the exhaust. hopefully its just leaking at the connection points so I can solve the problem with some remflex gaskets and be done with it.

Awesome! Keep going! I will probably have to do 3/4 of this stuff when I try to start my '82. FWIW, mine hisses too, I think it is normal, at least to some extent.

Great read! I've heard about this early EFI system but have never seen one and have no experience with them, but I find this very interesting.

I just discovered this thread this morning. We have an 81 Imperial with EFI and runs well. We enjoy it. It can be temperamental at time, and like with any 40 year old car that is driven regularly, requires a lot of periodic fixes. Otherwise we have had good luck and have owned it for 8 years. 139K and likes to be driven a lot. We have crossed the country three times in this car.

Ok, back to square 1.

Looks like I need parts, and more troubleshooting. No thanks. Converting to carb and points vacuum advance distributor. Why points? Because I have one on the shelf.

Heres all the options I can think of for dealing with fuel delivery. I will be left with the stock fuel tank and in tank pump. The pump puts out max about 29psi. It was the control pump on the throttle body that changed the "low" pressure to high pressure, and the control pump is going bye bye.

So, stock tank and in tank pump with lines already in place leading right to top of intake. I need to do this as cheap as possible, Low on funds and this is going to be a daily driver so gotta get it done soon.

Option 1: rewire pump, Use a bypass regulator and regulate psi to eddy carb, sending the rest back through the existing return line.

question: Whats the cheapest regulaor I can accomplish this with? I saw a quick fuel 30-899qft but I dont know if it can handle 29psi. I also saw a tanks inc. regulator rated for 30-70psi input, does that mean it cant handle less than 30 psi? both of those are $75


Option #2 Unplug pump. Install a mechanical fuel pump (cheap!) and pull fuel through the unplugged in tank pump

Question: Some in tank pumps will allow this, in fact chevy guys with tbi camaros have done this when swapping to carb. does anyone know if mine will?

Option #3 install mechanical pump, drop tank, remove pump, extend hose to bottom of tank. I can rig up a sock at the end of hose for extra protection, although my car already has 2 fuel filters between tank and engine.

Option #4 Install exterior low pressure fuel pump and cheaper regulator and pull through tank pump

Option #5 same as #4, just extra step of removing in tank pump and extend hose to bottom of tank

Option #6 Rockauto dodge mirada gas tank $85, sending unit $55, then mechnical fuel pump $20



What do you guys think is best option 1 through 5? Or any I havent thought of? Remember, low dollar

What are you going to do with the old EFI parts ?

SELL THEM

Ok so I waited and got better parts for my conversion:

Proform 66991 kit: vacuum advance 2 wire distributor, 2 prong ballast resistor and 4 pin orange box.

Summit racing 750 vacuum secondary carb with throttle stud adapter and tranny kickdown extension

Edelbrock Performer 2176 Intake with MR Gasket Ultra Seal intake gasket .060

NGK GR4 plugs

delphi mechanical fuel pump.


Got most of the wiring sorted out, and I have a question about the ballast resistor and starter relay. My current Ballast Resistor is 5 prong with 3 different resistances, and the starter relay is 6 prong.

I'd like to simplify and clean up my wiring more, I dont mind the work. I have the 1981 FSM for my imperial and have followed the wiring diagram. I've already removed everything EFI, but I'd like to ditch the 5 prong ballast resistor and 6 prong Starter relay and go with a simpler setup from say a 72 Chrysler or dodge.

Im already getting a new 2 prong ballast resistor with my proform kit, can I get a starter relay from a 72 318 dodge and follow the 72 wiring diagram to alter my ignition?

Here's a picture of my stock S.R. and B.R.

Bump

run the ign1 (run) blue wire to the upstream end of the ballast and T'd to the blue/yellow ECU pentastar connector terminal (might be solid blue). run the ign2 (crank) brown wire to the downstream end of the ballast. connect that downstream end of the ballast to the coil positive primary terminal. connect the coil negative primary terminal to the black/yellow ECU pentastar connector wire. With the blue/yellow ECU terminal held at 9 0'clock, run the 11 0'clock ECU terminal (might be tan with a black tracer) to the male metal terminal on the ECU half of the zigzag pull apart zigzag connector. the female counterpart on the pickup zigzag will be black, the other should be orange/orange. On the SR, duplicating the early stuff: I would run the ST terminal on the ign sw to the "ign" terminal & the "sol" large brown wire down to the starter solenoid & run the "grn" terminal to the NSS switch or permanently ground it as desired. EDIT we might (highly likely) be able to keep the current SR & just delete the one or two wires that wont be used when retrofitting to the earlier setup, we'd just need to find out what goes to where on the FI for a start.

Actually the in tank pump used it's own ballast resistor seperate from the 5 terminal resistor. I deleted that and terminated the big green wire going back to the fuel pump fuse.

Just wanted to wrap this thread up. I completed my conversion by using the 2 terminal ballast resistor that came with the proform electronic ignition kit and I ditched the 5 terminal oem and the fuel pump ballast resistor. I was able to make the starter relay work as well. To make the oem gigantic alternator work, I had to keep the body of the a/c compressor in place due to the pulley that the alt belts ride on. To clean up this engine compartment even more (if you want to delete the a/c and air pump), switching to a 2 groove pulley crank pulley and matching alt, water pump and power steering would be best. that will have to wait though as cat delete and dual exhaust are next in line for engine upgrades.

The only question I have about the mech fuel pump swap is, does the motor actually have a fuel pump eccentric bolted to the front of the cam?

Oh yes, and I used a standard 70's-80's delphi mechanical pump and hooked it to the 3/8 fuel line and capped the return line. I did have to remove the in tank electric pump as it wouldnt pull through it, and I just used some 3/8 hose to extend the pickup where the pump used to be.

The factory conversion manual does not include a cam replacement, which tells me that this is either the same 2 barrel cam that came on other 81 passenger cars with carbed 318's, or the cam for imperials came standard with the eccentric.

On a SB, the fuel pump eccentric is bolted to the front of the timing gear...... It's not part of the cam like a BB.

If you've bolted the pump on and it works, then it's obviously there.

My bad, didnt know that.

Supercuda this was a budget build and the a/c didn't work to begin with. Spending money on r12 or a conversion kit is the last thing on my list, plus any weight saved on this dog is a plus. Now, because I had to use the compressor for the pulley, I will be putting the lines back on. When money isn't tight I may even see if it holds a charge, i like having a/c