First shakedown cruise gave a jerky ride

[bruscreen]

I just got my Delorean running well enough to leave the yard and explore the roads for the first time. I attended a local cruise night and then visited my mechanic for some troubleshooting. Overall, about 10 miles added to the car. I'm guessing, because the speedometer never twitched, but that's beside the point. Overall, I'm just glad it finally got out of the barn, and now I'm learning what the real issues are. I posted a full writeup on the excursion on Google Plus (https://plus.google.com/u/0/b/111924785377158857477/111924785377158857477/posts/dQTKxNEYqDc) if you want to see the details.

The biggest question this trip raised was, why does this stick-shift car jerk me around and fall out of gear? It's not always the same gear that causes the problem, and it usually goes away when I switch gears, though I went through first and second before finding a smooth ride in third on the last leg of the trip. When it's acting up, the engine RPM will stay steady, but the car will intermittently accelerate, and if the RPM is high the results could give a person whiplash.

[Jonathan]

Is the car staying at an accelerated speed, or is it just increasing out of no where? It could be partly related to your throttle spool not springing back properly, or perhaps the cable is pinched somewhere along the sheath. There is a de-ice shield/throttle cable recall you could read up on. Not likely that is frozen this time of year, but there are a couple odds and ends in that recall kit that are supposed to help your throttle cable from getting pinched.

Or maybe it is somehow related to the butterfly valves not operating smoothly in the intake arrangement? There is also an idle speed microswitch that has a small adjustment on it that will let it engage at the right point. Basically when you let off the gas, that throttle spool extension lever comes into contact with the microswitch and kicks in the idle speed motor. Might be something related to that. I'm guessing a little bit on your manual transmission as I have an automatic, and the autos have two of these microswitches where one of them is more related to the transmission going into a kickdown gear when you hammer the gas.

Any chance it is related to somehow your brakes sticking and unsticking? That might explain the RPM's staying the same yet the car going faster. You have two parking brake cables going back to the rear wheels (one to each). If that isn't it, could be a caliper or two sticking the then releasing or something. If it was throttle related, you would think it would change the RPM's, but you're saying it isn't.

Those are some ideas. Not short and not simple. Sorry, I'm thinking maybe if one of the Super Dave's chime in they might have something to suggest more straightforward...

[bruscreen]

Thanks for the input. I doubt it's the accelerator cable, I can hold the pedal still and the car acts like the motor runs, quits, runs, quits. The tach tells me this isn't the case but it feels and sounds like it. Back brakes are definitely sticking, but that seems to be a steady drag. The air intake does stick a bit sometimes, but how would shifting gears help with that?

Here I go posting while nodding off again, will take another look after I catch some sleep.

[bruscreen]

Is the car staying at an accelerated speed, or is it just increasing out of no where? It could be partly related to your throttle spool not springing back properly, or perhaps the cable is pinched somewhere along the sheath. There is a de-ice shield/throttle cable recall you could read up on. Not likely that is frozen this time of year, but there are a couple odds and ends in that recall kit that are supposed to help your throttle cable from getting pinched.

The maximum acceleration isn't any higher than it should be, it just cuts out and starts up again. The engine doesn't rev / drop off when it's not in gear. I have the de-ice recall kit, just waiting until things run right before installing it, since the open throttle spool is convenient for troubleshooting.



Or maybe it is somehow related to the butterfly valves not operating smoothly in the intake arrangement? There is also an idle speed microswitch that has a small adjustment on it that will let it engage at the right point. Basically when you let off the gas, that throttle spool extension lever comes into contact with the microswitch and kicks in the idle speed motor. Might be something related to that. I'm guessing a little bit on your manual transmission as I have an automatic, and the autos have two of these microswitches where one of them is more related to the transmission going into a kickdown gear when you hammer the gas.


The idle speed switch sounds like something to look at, if it's making contact when it shouldn't be. What would happen if something pushed the switch while the throttle was half open?



Any chance it is related to somehow your brakes sticking and unsticking? That might explain the RPM's staying the same yet the car going faster. You have two parking brake cables going back to the rear wheels (one to each). If that isn't it, could be a caliper or two sticking the then releasing or something. If it was throttle related, you would think it would change the RPM's, but you're saying it isn't.

I mentioned last night that the brake seems to be a steady drag. I suspect it's the e-brakes that are holding. When the acceleration stops, the car coasts just as well as if I pushed in the clutch. Could it be clutch related? I haven't touched the clutch or transmission yet.

[David T]

If the car has been sitting for a long time you may have issues inside the clutch. The brakes are dragging because the calipers probably need to be rebuilt. Make sure you have enough gear oil in the transaxle. If it still jumps out of gear you will need to go over the shift linkage. You probably have worn rubber bushings and the linkage needs to be cleaned, lubricated, and adjusted. You have the right idea though, getting it moving will make all of the problems come out. Keep the trips short and close to home till you build up confidence in the car. If the tires are over 7 years old replace them, battery 5, wiper blades too. If the brake and clutch fluid is dark and thick you will be rebuilding the brake system and the clutch hydraulics. If you still have the red plastic clutch hose replace it with the S/S braided metal hose. If it still keeps jumping out of gear you may have a problem with the locking nut inside the transmission.
David Teitelbaum

[DMC5180]

First, what have you done regarding the fuel system. (Focusing in the tank) One thing that would cause your whiplash buck and jerk issue.

Partially broken/cracked fuel pick up hose at the pump fitting. ( I've seen this first hand) When the fuel gets down the right level, you let the clutch out and fuel sloshes rearward in the tank un-porting the pump nipple. It will suddenly suck air causing the system to abruptly loose pressure and shutdown. The car nose dives, fuel slushes forward and the pump gets a fresh slug of gas and the engine takes off again. You will also likely here rather loud pump vibration noises coming from the console area console area. The fuel pick up hose is very soft when submerged in fuel over tightening the clamp can cause the hose to fracture next too it.

[Ron]

The air intake does stick a bit sometimes, but ...?
What do you mean here?

[Bitsyncmaster]

First and Second gear can feel jerky in our cars. The gear ratios are pretty high and if your hard on and off the gas it will jerk.

[bruscreen]

What do you mean here?

If you pull the air filter off and push the plate down (not sure what it's called?), sometimes it sticks a little at the top and sometimes it doesn't. I'm told it's just the old gas, and will clear up, but it could throw off the fuel/air mix a bit.

[bruscreen]

First, what have you done regarding the fuel system. (Focusing in the tank) One thing that would cause your whiplash buck and jerk issue.

Partially broken/cracked fuel pick up hose at the pump fitting. ( I've seen this first hand) When the fuel gets down the right level, you let the clutch out and fuel sloshes rearward in the tank un-porting the pump nipple. It will suddenly suck air causing the system to abruptly loose pressure and shutdown. The car nose dives, fuel slushes forward and the pump gets a fresh slug of gas and the engine takes off again. You will also likely here rather loud pump vibration noises coming from the console area console area. The fuel pick up hose is very soft when submerged in fuel over tightening the clamp can cause the hose to fracture next too it.

My hose was broken off at the pump end, the other end was fine so I flipped it around. I may have to go back in there, maybe replace the hose. There was about 4-5 inches of gas in the tank when I pulled the sending unit out to check. The local gas stations were closed or I would've filled up. When it sucks air, do you see a change in the tach or just lose power?

[bruscreen]

If the car has been sitting for a long time you may have issues inside the clutch. The brakes are dragging because the calipers probably need to be rebuilt. Make sure you have enough gear oil in the transaxle. If it still jumps out of gear you will need to go over the shift linkage. You probably have worn rubber bushings and the linkage needs to be cleaned, lubricated, and adjusted. You have the right idea though, getting it moving will make all of the problems come out. Keep the trips short and close to home till you build up confidence in the car. If the tires are over 7 years old replace them, battery 5, wiper blades too. If the brake and clutch fluid is dark and thick you will be rebuilding the brake system and the clutch hydraulics. If you still have the red plastic clutch hose replace it with the S/S braided metal hose. If it still keeps jumping out of gear you may have a problem with the locking nut inside the transmission.
David Teitelbaum

I'm planning to have the calipers rebuilt and the rotors turned, when I get the car to a lift. I also want to take care of the fuel accumulator & filter while it's up there, and I'll add the linkage to the list. I'll have to check the fluids before I move it again, IIRC that's under a panel under the hood? I got the tires, battery and wipers done already.

[DMC5180]

My hose was broken off at the pump end, the other end was fine so I flipped it around. I may have to go back in there, maybe replace the hose. There was about 4-5 inches of gas in the tank when I pulled the sending unit out to check. The local gas stations were closed or I would've filled up. When it sucks air, do you see a change in the tach or just lose power?

Did you find the broken hose before or after your first drive. Interesting that you flipped the hose around. This would be suspect to me. You may have installed it in such a way that it is now collapsing or kinked. The hose is only ment to be installed one way.

You just loose power. The Tach is reading electrical pulses from a rotating Distributor shaft. You have a Manual Transmission that is mechanically connencted to the engine via the Clutch. If your in Gear, the engine RPM will remain relatively constant to wheel rotation. Say your driving at hwy speed and abruptly take your foot off the pedal. The engine does not suddenly go to idle. The speed and rpm come down relative too one another as long as you don't push in the clutch.

If your air plate is sticky, that could cause some of what you are experiencing. I would also expect you to have engine coughing and stumbling as it goes lean on acceleration. You step on the pedal opening the throttle plates but the Air plate does not open relative too the sudden need for air and fuel.

[Ron]

If you pull the air filter off and push the plate down (not sure what it's called?), sometimes it sticks a little at the top and sometimes it doesn't. I'm told it's just the old gas, and will clear up, but it could throw off the fuel/air mix a bit.
I was hoping you weren't going to say that .
This is the next thing I would look into. Whatever is causing it, scars or dents from being dropped, trash or old fuel deposits, etc. -- It MUST be free.
I'd lift the FD and if the plate then seemed free, go ahead and completely remove the FD and check out the plunger and bore. Be careful, the plunger should be free enough to fall right out of the bottom of the FD.
...and see that the roller where the plunger and plate contact each other is smooth and free.

[bruscreen]

Did you find the broken hose before or after your first drive. Interesting that you flipped the hose around. This would be suspect to me. You may have installed it in such a way that it is now collapsing or kinked. The hose is only ment to be installed one way.

You just loose power. The Tach is reading electrical pulses from a rotating Distributor shaft. You have a Manual Transmission that is mechanically connencted to the engine via the Clutch. If your in Gear, the engine RPM will remain relatively constant to wheel rotation. Say your driving at hwy speed and abruptly take your foot off the pedal. The engine does not suddenly go to idle. The speed and rpm come down relative too one another as long as you don't push in the clutch.

If your air plate is sticky, that could cause some of what you are experiencing. I would also expect you to have engine coughing and stumbling as it goes lean on acceleration. You step on the pedal opening the throttle plates but the Air plate does not open relative too the sudden need for air and fuel.

When I bought the car, the pump was out of the tank & non-working, so I got to re-assemble it without the benefit of having removed it. I found half an inch of the pickup line lying in the bottom of the tank, and the broken end stuck onto the pump. I didn't see any signs that the hose would be directional, that's a new one by me. Guess it was enough to get me running, but it's probably time for a new one.

Yes, it runs lean and stumbles a bit, which was part of the fun... I've been assured that the sticking is caused by some gummy old gas that will dissolve with driving.

I saw a comment somewhere today that these engines prefer high test, and I'm sure they'd rather not have the ethanol. I'm thinking of adding a few gallons of non-ethanol 91 octane before I move the car again, since several local shops recently started offering it.

The good thing is the car does move on it's own, so once I scrape up money for parts, I can take it to a shop with a lift. It may be a while before that happens, as my daily driver has dibs on that lift right now...

[bruscreen]

After reviewing the parts and some pictures, I think the hose I flipped was the return line not the pickup. It's been a few months. Here's a pic I took of the pickup hose before I started cleaning the tank. 11668

[DMC5180]

The engine is designed to run on standard pump gas. 87 octane. in the Owners manual it states 88 RON which is the british equivalent to our 87 R+M. Some people claim they can tell a difference between 10% ethanol blend and non- oxygenated. I've run my car on standard pump gas (87) w 10% blend for 18+years with no i'll effects what so ever. I have tried a couple tanks of non-oxy 91 which made no difference at all. That said, cars with stage II upgrades must run 91 or better regardless of blend option to help prevent detonation.

Assuming you went in a cleaned the tank. You may want to run a couple cans of Berrymens B-12 chemtool through the tank(system). (It's primarily acetone with a blend of a few other chemicals) use as recommended. High concentration (1/4) tank. This should dissolve any goo in the system and flush it thru. Also you should remove the banjo bolt hose connections on the CPR/WUR. It's the thing mounted on the Rocker cover to the left of the Idle speed motor. The larger bolt port has a screen under it. You want to make sure the screen is clean. No bits of rubber or debris.

As RON mentioned the the control plunger MUST operate smooth and free. It is a very precision fit any metal bur would be very bad. Hopefully that is not the problem and it's just a little gum left over.
BTW: do not push the air plate all the way down. doing so could cause the plunger to become stuck up inside the the bore. It is a very difficult to get back out if that happens.

Someone posted photos of an FD that needed to have they plunger pulled out. I believe they got lucky and were able to remove it. I just don't know were that post is anymore to reference.

[bruscreen]

I did scrub the tank with acetone, but I haven't replaced the accumulator and filter or any lines yet. I wasn't sure about the octane requirements, but I'll bet nobody thought of 10% Ethanol when these gas lines were developed. I've also wondered about injector cleaners, but I'm worried about what happens if deposits in the line free up only to stick someplace else, like in the distributor or something.

I took another look at that plate last night and it's moving freely for now, though we'll see how long that lasts.

[DMC5180]

Actually back in the day they did have Gasohol (methyl alcohol) based. It was very corrosive to existing fuel systems of the day. Probably, one of the reasons they used the Plastic fuel tank.

The Original Flexible Exterior fuel lines have a Nylon inner core. That core doesn't disintegrate. The outer black jacket falls off and just looks ugly. The Black crap in the tank comes from the FP Boot breaking down.
The FUEL FILTER is supposed to catch the junk to protect the system. Unfortunately minute particles always seem to get through to some extent. This is why I mentioned checking the Inlet screen in the CPR/WUR it's a good indicator for potential contamination problems.

[dvonk]

Actually back in the day they did have Gasohol (methyl alcohol) based. It was very corrosive to existing fuel systems of the day...

our family had a 1979 Maxima when i was growing up, we kept it until about 1992. the only time it was ever in the shop was in the mid-eighties when my dad put a tank of ethanol gasoline in it.

that was the last time he used ethanol gas.

[DMC5180]

our family had a 1979 Maxima when i was growing up, we kept it until about 1992. the only time it was ever in the shop was in the mid-eighties when my dad put a tank of ethanol gasoline in it.

that was the last time he used ethanol gas.


That 79 maxima would have had a Carburator and probably a smog pump. so It's not surprising. I'm not sure when Methyl gasohol transitioned to ethanol blended stuff. But it's been around since the mid-eighties in the midwest that is. Other parts of the country used MTBE (methyl tetra butyl ethane)

[dvonk]

with all the corn we grow in the "Cornhusker State," im surprised '89' is the only octane gas that contains 10% ethanol.

[DMC5180]

Around here 10% ethanol is in all grades at most stations but some do have "OFF ROAD/Classic Vehicle" Non-oxygenated Premium.

[bruscreen]

Around here, it's been impossible to buy gas without ethanol for a couple of years unless you could pull up to the dock at the right marina. Pumps with non-ethanol 91 octane are just starting to pop up, and I make sure to use them whenever I can. At the very least, I don't want the stations to give up for lack of demand.

I added a few gallons of non-ethanol to the tank tonight and drove it home (about a mile). The engine doesn't rev up well when cold, and even once it warms up it gets flaky occasionally. I was moving along at about 20mph on a slight grade and it started sputtering and jerking around a bit. I let off the gas and pushed it again and it smoothed out, so I think it's just some "gum" working it's way out of the lines...

Now that I have it home for the weekend, not only can I tinker in my own garage, but I can get it out on a dead end street where I don't have much traffic to deal with. First up: freeing up the brakes.

[bruscreen]

Finally found & fixed the jerking problem today. I was testing the brakes and it started acting up again. The further I drove, the lower the RPM at which it would lose power, until it quit on the side of the road. I pulled out the fuel pump and sure enough, the pickup line had broken at the bottom of the pump. Further complicating matters, I had left one of my shop towels in the tank when I finished cleaning it out, and the pump had sucked it in. So apparently, I was running on whatever gas the pump could wick up through the rag! Pulled out the rag, hooked up the hose, and put 30 miles on the car today without further issues. The pump runs a lot quieter too! I see a new hose in my future.

[Michael]

I visited your homepage and I gotta say that paint sure cleaned up nicely, and blue is definately my favorite color I have seen on a D so far.

[DMC5180]

Finally found & fixed the jerking problem today. I was testing the brakes and it started acting up again. The further I drove, the lower the RPM at which it would lose power, until it quit on the side of the road. I pulled out the fuel pump and sure enough, the pickup line had broken at the bottom of the pump. Further complicating matters, I had left one of my shop towels in the tank when I finished cleaning it out, and the pump had sucked it in. So apparently, I was running on whatever gas the pump could wick up through the rag! Pulled out the rag, hooked up the hose, and put 30 miles on the car today without further issues. The pump runs a lot quieter too! I see a new hose in my future.

Glad to here my diagnosis back in post #6 was correct:yesss:. A new pick-up hose should fix this things right up. Now it's on to other issues that will inevitably crop up. Keep us posted on your progress.