Imperial Homepage -> Repair -> Fuel -> 1981-1983 -> Acceleration
Question from Don (1981):
My problem is that my '81 will not start. This car has the factory conversion carburetor and 318 engine. Here's a little history behind the car to help with diagnosing the problem. The car sat for 4 years with a virtually empty gas tank. Before this it ran really well until the carburetor gave out. We had the carburetor rebuilt back in May, put in a new battery, flushed the cooling system, had the oil changed and checked all the fluids. All seemed well, in fact even the mechanic who worked on the car was extremely surprised at how well it was running for sitting for so long. The car was running quite nice accelerating fine, no strange noises etc. Then it started developing extremely poor acceleration, very unresponsive and when in park, idled so low that it was hard to even tell if the car was running. There were times when, while driving in town I thought it would die on me completely. But, this didn't happen all the time! One day I would take it out and it would drive as sweet as could be. A few days later it would start acting up again. In trying to figure this out I did notice that it drove poorly after filling the gas tank. The last time I drove the car, the acceleration was very poor, it idled really low in park and lets just say I was thankful to make it home. I sat in the driveway, revved up the engine a bit, turned it off, then went to restart it and I heard a somewhat large POP on the passenger side under the hood. Now it won't start. It turns over just fine. Of course not knowing what the problem was or where to start, my husband and I replaced the following parts: coil, distributor cap and rotor, voltage regulator, co-2 sensor and the spark control computer. Still will not start. Could the jets be plugged? There's quite a heavy smell of gas when we go to start the car without pumping the accelerator.
Sounds like a clogged fuel line/fuel filter/carburetor jets/ etc. "Pop" was probably a small backfire from very irregular fuel flow. Not an expert, but that's where I'd start looking.
I would suspect when filling up gas tank, it may have jarred some debris loose in gas tank. It may or may not have gotten in the carburetor and is causing the problems. First thing I would do is make sure I have spark at the plugs. Then you can be sure your working in the right area. You say you smell gas without pumping the accelerator, I would pull a sparkplug or two and see if they're are fuel fouled. If they are, you're going to have to replace them, if you want to give the engine a chance to start. Next I would check fuel pressure just before the carburetor, (not sure what pressure should be in a carburetor setup) and see if lines and filters are clear from carburetor back to fuel tank. If the flow and pressure is good, you're probably going to have to take top half of carburetor off and check for debris. Process of elimination.
My guess would agree with what some others have suggested, namely crud in the gas supply. I suspect your float bowl is overflowing (in the carburetor), either due to a stuck needle valve, or a float that has lost it's buoyancy. Either way, you should take the top cover off the carburetor and inspect things in there.
I would start by checking the fuel pump pressure to the carburetor. There is a good chance that rust was deposits were created in the gas tank and have restricted the fuel flow. If that is the case then add two fuel filters in the fuel line. One before the fuel pump and if possible one before the fuel tank.
Another possibility is that the timing belt/chain is sloppy but when you stated that the car acted up after a refill makes it possible that the fuel venting system is not functioning. I had that problem with my AMC. I replaced the fuel filter and replaced it with a G-2 filter and left the vapor line open. My fuel mileage increased and the problem was solved.
The last thought is that it could be vapor lock. filling the tank when the engine is warm or driving slow and then accelerating could cause vapor lock. Sterling Marlin has that problem in his NASCAR Dodge.
Follow-up from Don:
Dan and I worked on the car yesterday. Yes, we do have spark and we do have fuel, but we do not have an Imperial that will start!! We are both stumped. Of course we are trying to walk through all the possibilities as to why this car won't start. We've come to several conclusions.
The throttle valve may not be working properly allowing the fuel/air mixture to enter the intake manifold and on to the engines cylinders. The carburetor itself needs to be adjusted for proper fuel/air mixture, the mixture right now could be way to lean to ignite or maybe we just got a hold of some really bad gas. The timing could very possibly be an issue, one that I'm not sure we can check on our own, if I'm wrong let me know. These were our thoughts, and of course any thoughts or suggestions will be helpful. I do have another question though...when the engine is cranked there is an orange ark over the distributor. Shouldn't it be a hot blue arc when starting and go to orange when running? I really thinks the gas is bad, so we will probably end up removing the gas tank and cleaning it out which I'm sure can't hurt especially since the car sat for so long.
How about a clogged exhaust pipe or converter?
I'm a little confused about your question but let me try and answer it anyway. There should be NO visible sparks ANYWHERE when the car is running. Period. Full Stop. If there are, you car is probably missing and running poorly.
If you test the spark by pulling a wire and letting it arc to a good ground (not the fuel line please) you should a good spark. Blue is best but I don't think I've ever seen anything but orange. If you can get a 1/4 inch spark, your plug should fire.
Sounds like your cap is shot. The good news is they are cheap and readily available. My 64 would barely run. Changed cap and plug wires and it ran like a top.
Question from Rob (1982):
I'm replacing all the rubber fuel lines and filters in my '82. I believe that my starting problem comes from the fuel draining back through the pump(s). There are (at least) two check valves listed: one before the control pump and one at the regular pump. I'd like to replace these, does anybody know a part number or at least the specs so that I can find a current replacement?
Reply from Dick:
Your ASDM is doing the right thing since you hear the rear pump come on. The control fuel pump in the HSA is very likely working also, but to verify that, take off the air cleaner lid and have someone cycle the key while you listen or feel the pump, and watch the fuel nozzles - you should see a brief squirt from them also - I think you'll find it is cycling also. If it is not, check your Fuel Pressure Switch for resistance - it should be less than 10 ohms. These are well known as a problem site on these cars.
If you have the shop manual, go to page 14-104 (in the 81 manual, anyway, it should be close). This is basically the "No Start/Fuel test #3" (SOME OF THESE TESTS MENTION THE EFI TESTER - DO NOT USE ONE, EVEN IF YOU HAVE IT!)
If you get the short squirt of fuel during the cycle, your car should be starting OK. If you have not done so, I think it's time to check the compression on this engine.
Follow-up question from Rob:
Why do you think I should run a compression test? The car runs fine and doesn't burn oil. It just takes some time to start. If you have been driving it and shut it off for a second or two it will usually start immediately. Only two big problems I had were on HOT days after a stop of between a half hour and an hour. For these reasons and the aftermarket fuel pump sucking fuel UP through the inactive in-tank pump, I suspect a fuel line problem. Would compression affect the starting, but let it run this well?
Reply from Dick:
The short answer is yes, low compression will show up first in difficulty starting. Compression is an easy thing to measure, and tells a very large percentage of the whole story about your engine's condition. As an example, I offer my 300,000 Mi + "Mahogany" 81 Imperial - even at the end of life, it drove perfectly, burned no oil, and was fairly smooth and quiet, but it did have a somewhat rough idle. It also would emit some oil smoke when started if it had not been driven for a week or so. It showed no deterioration in MPG or performance that I could detect. It was a tired looking car when I bought it, in 1988 or so with about 130,000 on it, but it was supremely comfortable (cloth seats in the 1981 only style loose pillow design) and I drove it everywhere for about 12 years.
It became harder and harder to start - finally to the point that I began carrying a few ounces of gas with me when I was going anywhere. The compression was in the 90-110 range on 6 of the cylinders, and 40 on one, 70 on the last one - signs of a very tired engine (which I already knew, of course). I sold that car in 2002 (as a parts car) to another collector - he is in Finland and I have not had a report as to what he did with it - but he had a much nicer one so I suspect it hasn't been driven since. I did tell him how to start it, though.
If you put a pressure gauge on the fuel inlet to your HSA (the smaller of the two metal lines), you can measure the fuel available for starting. You should see about 12-14 PSI there when the purge cycle is occurring. You should also see a squirt from the fuel nozzles above the butterfly throttle valves. If you have the fuel there, the car should start right up. If it doesn't it's time to start looking for another cause.
I assume your plugs, wires, cap, rotor etc. are all in great shape. As you probably know, there has been a reported high failure rate of the reluctor coil in the distributor which has caused many high temperature running problems, but I'd not expect this to cause only a starting problem - if the pickup is failing, that would also cause your engine to stop anytime, not just when starting.
Question from Paul (1982):
I just bought this car a few weeks ago and have since joined the club. Thanks for welcoming me. I've enjoyed the club so much in the last couple of weeks that I've already gone out and bought a '68 Crown Coupe (runs great, 99.9% original from a man who bought it in '69).
Anyway, about my non-running '82. It has the EFI still installed. I just put new plugs in it and a new 0-2 sensor, fresh gas, new air filter and a new battery.
Result- If I crank the car FOREVER, it will fire and immediately stall. If I give it some gas (step on pedal) as it fires it will increase RPM and then die within a couple of seconds. If I then crank it again it will fire and stay running (very rough) as long as I keep my foot on the gas. WAY DOWN on the gas. It will NOT idle, not even close, it will run above about 2,500 rpm only and it sounds like it's running on 5-6 cylinders only. Actually it feels like the plug wires are on wrong (they're not, I checked).
Where should I start? I've read briefly through the info on club website but most of it deals with vehicles that idle rough or have low power. Mine just isn't drivable at all. I'm sure that I'm not the only person to come across this problem as I see '81-'83 Imps for sale cheap all the time that "don't run". This car is extremely clean. No dents, no rust, great interior. As soon as I get it running it will go out for a fresh coat of paint.
Reply from Dick:
This may take a while, and is going to lead you into doing some research yourself. As a first step, though, remove the new air filter element and reinstall the lid tightly, just to make sure you don't have an air leak induced by a poor fitting air filter element.
Assuming this is not going to help, the next step is to carefully inspect all the wiring and vacuum hose tubing, making sure all the harnesses are completely plugged in with all pins and connectors intact, and that the vacuum hose routing is exactly in compliance with the information on the passenger inner fender sticker (it's near the hood hinge and may be quite dirty, but it is there.)
Assuming you haven't yet found a problem, read up in the IML archives about how to run the car with the air cleaner lid off. Basically, you need to fool the computer into ignoring the air flow sensor by telling it that you are cranking to start the engine.
Once you know the trick for starting the car with the lid off, have a helper try to start it while you watch the fuel plumbing lines inside the air cleaner assembly. I'm guessing you will see some liquid fuel leaking from somewhere, probably the fuel pressure switch tubing, or the nozzle assembly valves. This is all very simple stuff, which you can remove, disassemble and clean with spray type carburetor cleaner, so that you get all 8 nozzles spraying nicely. Then put it back together and reassemble the lid etc., to see if you've fixed anything.
If still no go, take a very close look at all the other air seals in the whole top of engine hardware. Pay particular attention to the lid gasket, and to the one beneath the hydraulic support assembly.
If you don't have the two manuals for this car, get busy on eBay or from a literature dealer and find yourself a set, these are mandatory for maintaining this car.
Don't give up - just listen to those of us who have fought our way through all the sin previously committed by the unwashed in trying to get these cars to run. Once you have it all back to normal, you will be delighted in the way the car starts, runs, and drives!
I doubt this is enough information to solve the whole series of complaints, but see if you can plow through the above and report back to us. There are 5 or 6 people on here who know a lot about these cars, and one of us will jump in with good advice on every point.
If you don't already have one, it is a good idea to pick up a decent analog type volt-ohmmeter. Radio Shack has an adequate one for under $50.
As someone else has implied, 90% of the engine problems on these cars are blamed on "that damned EFI", and when it's all said and done, about 10% of them turn out to be actually related to its being an EFI car.
Follow-up question from Paul:
Thanks for the great advise. I'm planning on looking at the car this weekend (after tuning-up my 68). If the lid gaskets are bad, is this something a dealer would still have, or should I improvise with a generic seal? I bought this car for next to nothing ($250, it sat for about 5 years) and I don't mind putting a few bucks into it as I plan to use it as a daily driver (kind of). Heck if this engine doesn't work out, I was thinking a newer Magnum 360, or even a V-10 from a truck.
At the parts store I ran into a little confusion on fuel filters. It listed two types, one seemed to be "normal" with a simply "in" and "out", but the other had a third, smaller in/outlet. I haven't crawled under the car yet to check what's under there, but I found it interesting, and confusing.
I couldn't hear any pumps, pumping, but the engine is obviously getting fuel, as it stinks of gas and will somewhat start. Ever seen fire coming from the crankcase breather??? (the breather hose is gone, but I've completely sealed the inlet the air cleaner housing until I get a new one)
I have a sound understanding of modern fuel injection (which may hurt my chance of understanding this car). I read about the fuel "nozzles". Is this just a type of fuel distribution system, all feeding from a centralized, single injector?
Also, is there any type of electronic self-diagnosis system on these cars? Even my 97 Ram (with OBD-II) can be accessed by cycling the key.
Are parts still available at the dealer for these cars, or has Chrysler left us out in the cold (again)?
Reply from Dick:
These make great daily drivers, as they are superbly comfortable and quiet on the road, and get very good mileage. What they are not, though, is performers. The are very slow off the line, with the 2:20 rear end, and 4500 pounds being pulled by a 135 HP engine. Once you get them rolling, however, they will cruise all day at 75 and give you 22 MPG or better doing it.
You can make a good air cleaner gasket with closed cell foam, as used in weather-strip (it must be closed cell foam, however, anything else will let the air sneak in there without passing the air flow sensor. This drives the computer mad!
The EFI is throttle body injection, with 4 nozzles feeding 2 cylinders each at low flow rates, and 4 more chiming in for more fuel demand. The nozzles are controlled by fuel pressure, with the low flow nozzles opening below 20 PSI and the higher flow coming on stream above that. This function is entirely controlled by pressure operated mechanical plungers in the plumbing - no electronics involved at all here. The system monitors RPM, throttle position, fuel and air flow, temperature of fuel, air and coolant, time since startup, the O2 content of the exhaust, fuel pressure, brake pedal position, ignition key position and perhaps the phase of the moon, and compares this data with pre-programmed and memory data to set the flow of fuel. The computer is basically an analog in - analog out device, so it is not much like our modern digital controlled devices at all.
There is no provision for on board diagnostics. The dealers were supplied with a test set, which is little more than an box full of switches and meters. Some on the IML have this device, but I have not bothered with one, as I can learn quite a bit about what is going on with normal test equipment.
Chrysler dealers sometimes have parts, more often you have to run your needs on PartsVoice.com to see who can come up with what you need. You will need part numbers, of course.
The fuel filters are under the car near the driver's door hinge post. They are very normal in-line filters, with good availability. Take the old ones into NAPA and match them up.
I think your problem is more likely to be too much fuel than not enough. If you have flames coming out the breather, though, you may a have a cracked piston or worse. I think it's time to do a compression check! It also would be a good idea to smell the dip stick - if you smell gas, you have a bomb waiting to go off there! Drain the crankcase and refill it before doing anything else to the car.
Question from Joel (1983):
I have a 1983 Chrysler Imperial that I purchased about a month ago. It's in pretty decent condition, but does have some rust in the rear left & right quarter panel & the bottom of the deck lid. It has 130,000 Miles on it (but there is an asterix beside where it says that, don't know what that means) and gets from 15 - 20 US MPG on a tank.
Right from the beginning, whenever I would start it, it would crank over a bit more than what I would expect a "normal" car to do, although I did hear from a certain mechanic that due to it's older computer, that could be normal. It always drives & idles nice though. Anyways, here's what happened: I drove my car to work friday morning (7:30 am), and it did it's usual "longer than normal" start, all was good. It sat all day at work in about say 20 C (68 F) temperature. I finished work! around 5:00 pm and went to start my car. The first try I held the key in the "start" position for about 6 - 8 seconds, it just cranked, didn't fire once. This was kind of surprising, as it had never done this before. So I tried it again, nothing. After that, i tried pumping the gas pedal (I usually NEVER touch the gas pedal at all before or during starting) while I was cranking it, it actually fired one or two times but didn't start. Next, I pulled off the air cleaner cover, & I could smell gas( but it didn't appear flooded), so I left the cover off for a minute or two, then put it back on and tried again. Nothing.
So after that I went back inside to where I work & called AMA to send over a tow truck. Next ( about 30 mins had passed since I had last tried starting the car) I went outside again to see if I could start the car. I put the key in and cranked it...it didn't fire for a sec or two, but then caught a few times & started. For the first few seconds it ran rough, like it had too much / too little fuel, bu! t after that it smoothed out and idled like it has always had before (it idles nice btw). So now i'm a little scared about something like this happening again (i've been driving it for about 4 days since then and it's always started). Now would any of you guys have any idea what the problem could be and what I can do to fix it? I'm also interested in why it seems to need a few excessive cranks to start.
What is the service history of the car? The EFI cars are a bit fussy, they require a good set of spark plugs, good air filter element and most important of all is that the air filter housing is firmly fitted and preferably sealed with some (non silicone) sealant.
I have owned my '82 imp for 7-8 years now and find that differing ambient temperatures have the greatest effect on whether the engine will start right up or require more cranking, usually heat soak causes the most problems, this is where the car has been shut off for a short period after a longish run and a restart is attempted on a hot day, the engine will crank and crank but will refuse to start. My car has never had this problem but it is a regular EFI trait.
The importance of a firmly fitted air filter cannot be understated, the correct element must by fitted centrally in the housing, the housing MUST sit flat and firm on the HSA (injection unit) and all the pipe work must be fitted correctly, when lowering the filter housing onto the HSA you must ensure that the wiring loom which runs front and back is clipped to the housing and not trapped underneath also make sure the little vac hose is fitted to the snorkel and the lambda sensor wire is reconnected. Ensure that the PCV valve is working (shake it if it rattles it's ok) and firmly fitted into the rocker cover (if the rubber grommet is not holding the PCV tight replace it) and that the hose to the breather which sits in a grommet on the opposite valve cover to the PCV is fitted properly.
The above may sound like a lot but it only takes a few minutes to check, if you do not have the correct Chryler service manuals you should as they are the essential to an easy life.
What you will find from reading the IML and the service manual is that if the engine is flooded wide open throttle (WOT) while cranking will stop fuel delivery completly so only use this if you think the engine is flooded, i find with my car that a light throttle opening helps it to fire up quickly.
This was a frequent problem with early '80s, first generation computerized cars. In most, the ignition and the fuel system are both computer controlled. There are a guzillion reasons why these cars either stop running or won't start. In many cases, the trouble is intermittent and difficult to find. Many Auto Electric shops in the good old USA became very wealthy during the time that these cars were on the road. The sad part is, most of them never really ever figured out what was wrong with the cars. Eventually their owners became annoyed and sold them.
I hate to be so general here, but I know from experience that this was universally true among the big three and most likely others too. My newest Chrysler Product has always been my '68 Imperial. I have '80s offerings from each of the other major manufacturers, and have had occasional problems with both, although the G.M built cars have been much more reliable than the ones from Ford. I still run both of them on a daily basis.
When those Imperials were new, many people had exactly that kind of trouble with them. The cars will run perfectly, and for no apparent reason, quit on the road or refuse to start. Over the years I have found that the folks that were the most successful keeping those cars on the road were the ones who "loved them no matter what".
I have also found that reading the wiring diagrams and understanding where relays and sensors (both vacuum and electronic) are, and understanding what they do helps a lot. Relays with dirty contacts can cause an intermittent problem for years before they actually quit working all together. This is also true of sensors.
In summary, I would say that there probably is not one thing that anyone here can tell you that will solve your problem. If you love the car, you will become very accustomed to knowing under what condition your car does certain things. Eventually you will be able to make sense out of that information, along with the things that you read and study to make a good stab at finding the faulty part or parts. The other option would be to pay someone else to do that, but I offer this: back during the time that those cars were on the road there were few, if any mechanics that could trouble shoot them. Most people just got taken to the cleaners, and still couldn't depend on their cars to run when they were suppose to.
I believe the asterix means the dash has either been repaired or replaced. That was one of the '80's Imperials big problems. I knew someone that bought an 81 sometime around late '83 & he had the no start problem then. There were times when he would crank it till the battery was nearly dead, then leave it 15-20 minutes & it would start immediately. We worked at the same place, so I had given him a ride over to the Chrysler dealer several times when he brought the car to be fixed. Every time I was there, they had one or two of them in the shop with lots of parts removed & stacked all over the place. I asked the mechanic working on one of them one time I was there what was wrong with them, since every time I was there, they always had at least one like that. He didn't seem to want to volunteer too much info other then to say it wouldn't start. After word came out that the cars had major problems that would require a major retrofit & that the parts to do so were in very short supply & cost $2-3 K to accomplish, he got rid of the Imperial in a hurry at a big loss.
I had an '81 that did this same type of thing. After replacing quite a few things, I found that the control pump was weak. I pulled it apart, cleaned it up, and the car then started great. Cranking the car a long time does no good, because after a short time the computer shuts down the fuel. If it doesn't start within the first few rotations, turn it off and try again. Sometimes turning the key on and off a few times will get the pump to push enough fuel through to start it.
I have an '81 Imperial and have gone through many of the same experiences you have. For the past two years the car has worked quiet well. I use it as my daily driver and it always starts whether it is 10 below zero or 90 degrees. I am determined to keep the EFI and keep it as original as possible. When these cars work they are really a nice car but reliability is not their strong suit.
I don't have pat answers to your specific problem. It is intermittent and you would drive yourself up the wall trying to chase it down. Since it only did it once I would assume it was a fluke and dismiss it. You may be a little ucomfortable each time you go to start it but that is the way it is with these intermittent problems.
If you are up to the challenge of keeping a great car running like it was intended it can be very rewarding.
I would have the following advice:
1. You are on the right track to obtain the service manuals. They will be less valuable in troubleshooting than you would like but they go a long way in helping you understand the system and the function of each component.
2. I would try to acquire some spare parts. Some that are known to be good if possible. They are around but not easy to find. There are still some out there at a reasonable price. Particularly pick up a computer, a power module (inside the Hydraulic support plate) and probably a water temperature sensing unit. Other components would be helpful but not essential.
Make your appeal to the IML folks. They are very helpful.
3. Unless you are steeped in electronics I would not get into repairing the specific components. They are complex and difficult to diagnose. Change out components to find the culprit.
4. The electronics seem to me to be sensitive to moisture and humidity. If your starting problem occured under these conditions the problem will probably repeat under those conditions. When it is damp out make sure the car is completely warmed up and dried out when you shut it off.
5. It has been my experience that these cars start with less cranking in the winter than they do in the summer. Long cranking cycles are usually associated with high ambient temperatures. I would expect this is due to fuel vaporaziation and the inability of the system to quickly purge itself of fuel vapor. I don't know what can be done about this.
6. Even though it might seem so, the problem is not always in the EFI. Make sure the ignition system is in good condition. This includes spark plugs, plug wires, ignition coil, ballast resistor, and the hall pick up coil in the distributor.
7. A common problem is the failure of the air cleaner/hydraulic support plate to seal sufficiently to make sure all the air for the engine is passing the air flow meter. Check all seals and gaskets from the throttle base to the air horn to minimize leakage. Also make sure all vacuum hoses are tight and not weathered to the point they are leaking.
This is a lot of what my seat of the pants experience has taught me. I don't have all the answers but I have a car that is used almost daily for relatively short drives and runs and strarts good. Mine has just over 93,000 miles on it.
I have replaced several of the EFI components over the years and have found the computer and power module to be the most troublesome. I did implement the service fix of grounding the Automatic Shut Down Model to the engine.
Converting to a carbureted set up was an option for me at one time. My son was parting out a Dodge Mirada and all the components were available to me at no cost, including the fuel tank and intake manifold. I decided to give the EFI one more shot and I have never regretted it. A clean conversion that was not done by the factory is extremely hard to find. I have seen many that are real butcher jobs even though they do start and run.
Good luck on keeping your car running. It is a real challenge at times but if you enjoy a challenge and a nice running car it is worth it.
This page last updated August 22, 2004. Send us your feedback, and come join the Imperial Mailing List - Online Car Club