1983 Plymouth Scamp GT - Lacking in Performance

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portnoy

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My baby has been maintained over the years and has most engine components replaced after they fail one by one. What is irking me are some performace issues that have been starting to come to light. For starters, Something seems wrong with my gear ratio. (The speedo is disconnected but...) I can get to about 35-40 in 3rd gear before going over 3Krpm. 4th gear is anywhere from 35-50, and 5th and final gear gets me to about 65 max. I'm always in the right lane on the highway. Really doesn't go much faster than that, though i think i hit 70 once, downhill, in neutral.

That was during the return part of a one-hour drive on some decent grades through the mountains. Then the check engine light came on. After a cool down period of about a half hour it has been fine. Am I really looking at a permanent top speed of 65? Are there any tricks or tips in terms of maintenance or repairs that could help this out?

When jiffy lube forgot to put the oil cap back on my GF's 98 isuzu rodeo, there was a period where she was having to shift into higher and higher gears than usual to maintain average city speeds. It was only after this negligent error that her car started to remind me of my own...


I keep the fluids changed and filled regularly, and all the filters too.
If there's nothing I can do about this, anyone know how to tighten a parking break so I don't roll out the driveway?

Thanks in advance!
-Portnoy
 
Sounds like a fuel issue to me, I've seen this before, on my own '83 Scamp GT.

A few things to check, first is the fuel filter (Bypass style Return Fuel Filter), it may be falling apart inside and returning too much fuel back to the tank. Do Not Replace it with a regular 2 Port (In/Out) Fuel Filter.

Second is the Fuel Pump, test the pressure and flow. I can't remember the numbers anymore, but I'll check my FSM when I get a chance, and I'll let you know.

Third is the Rubber Hoses that connect the Steel Lines to the Tank, Pump, Filter and Carb. They may be collapsing partially or completely and starving it for fuel (I've seen this happen a lot, even on brand new rubber fuel hoses)

Fourth is the god awful nightmarish "Hoggey" (Holley) Progressive 2BBL Carb that was used on the factory 2.2L's. Most 2.2L Owners smash em with a BFH and throw em in the scrap pile, before bolting on a Weber 32/36 Carb. I've even seen some where people have bolted on 4 Mikuni Side Draft (Motorcycle) Carbs. but that's getting into some custom work, where the Weber bolts on with the supplied adapter kit.
 
There was a service bulletin on these to move the exhaust oxygen sensor wires into a separate connector. The problem was voltage tracking from battery to the oxygen sensor which then would lean out the carb.
 
abodybomber: yes, 2.2 - and, no, i haven't had the clutch adjustment looked at. Clutch is butter, the pedal is super easy to press and comes up pretty high

74Dusted: Maybe a year ago I replaced the hoses connected to the two ports of the fuel filer, I believe one or both had cracked, but I think it was purely superficial. I didn't replace the filter at the time, but it's worth checking. autozone didn't have the right filter, imagine that.

SSVDP: Whoa never heard of this. I don't believe it was ever addressed, though maybe I'll take a look and grab a picture in the light and see what's up.


Am I right in thinking that I should be able to go faster in lower gears in this car? A cousin drove it for 7 years before I got it, though if it was never addressed maybe he just assumed that's how it was and didn't think about it.

Thanks everyone for the replies, it means a lot
 
Yeah, the little Cruck should fly down the road at high speeds. They only weigh about 2100 pounds with a full tank of gas (and fully optioned with a/c, bed cover, console, etc)
 
There was a service bulletin on these to move the exhaust oxygen sensor wires into a separate connector. The problem was voltage tracking from battery to the oxygen sensor which then would lean out the carb.

rumblefish360 said:
SSVDP, that is amazing.
Click to expand...

Yep! I worked in Chrysler engineering & a tech I was working with figured it out by spraying the underhood with water. The problem was typically intermittent & the water made it show up. The oxygen sensor was zero to five volts so it didn't take much to send a rich signal to the computer which leaned out the carb. There was an eight cavity plastic connector & the ox sensor was next to battery voltage. I remember letting the wiring guys drive a car & it wouldn't go over 40 mph at full throttle. It was a simple fix to move the sensor into its own wiring connector. I even wrote the tech bulletin!
 
I am about to buy one of these little car/truck. So if needed where would someone get a hold of this tech bulletin? Surely not from my local dealer. They are not interested in helping anyone with an "older" car.
 
SSVDP: In case I can't find this service bulletin, am I correct in assuming that i would go about this the same way I would in, say, a tube amplifier? Separate the O2 sensor wires from the 8-bundle, and seal with heat shrink and maybe a small plastic tubing… And just the fact that they are away from the other wires is enough to do the trick? Do I need to reroute the wires too, like along a certain line? Sorry to be so inept, never seen an 02 sensor before

Dartnabout: If you can track it down (i haven't had any luck) wanna send it to me? i'll do the same

I'm very curious because i've still got the stock carb, and basically any issues i've had in the past few years have included a carb adjustment in some way, or that has been the only issue.

Thanks!
 
So hopefully the picture uploaded of what i'm working with. It looks like if i just crack open the plastic housing on the left and un-bundle the 4 oxygen sensor wires, rehouse the other wires and separately house the Ox wires we will be good. and they can just run alongside each other, though housed separately.

Unless that's the wrong idea
 

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Good tip on the O2 sensor wires!
Other things to look at should be: What was the code set with the Check Engine Light? That's the 1st place to start.
Next, the carbs had a rubber insulator plate that mounted the carb to the intake & they used to crack & cause vacuum leaks that would cause hard starting cold & lean conditions when warmed up. Spray carb cleaner around the base of the carb with it running(air cleaner on if possible) & listen for the engine to change speed.
Another thing is the possibility of the catalytic converter is clogged or partially blocked up & gets worse as it heats up. Check by hooking up a vacuum gauge to manifold vacuum & bring the enine speed up- if it continues to drop or is considerably low, possible catalytic converter failure. Also check for excessive back pressure. Many ways to do this, but the easiest quick check is to bring the engine speed up & see if there is a good amount of exhaust coming from the tail pipe. You can do this while doing the vacuum test if you have a helper.
What condition is the timing belt in? Has it been replaced in the last 60,000 miles? It's possible it may have jumped a tooth or so. That would definitely cause loss of power.
How is the ignition? Is it misfiring? What do your plugs look like? Plugs can tell a whole lot of the story on how it's running.
I hope I didn't throw too much at you all at once. Just some ideas of where to look.
I hope this helps. Good Luck!
 
portnoy said:
So hopefully the picture uploaded of what i'm working with. It looks like if i just crack open the plastic housing on the left and un-bundle the 4 oxygen sensor wires, rehouse the other wires and separately house the Ox wires we will be good. and they can just run alongside each other, though housed separately.
Click to expand...

Exactly!
ThAt looks like the connector but I remember it up front near the fan - after 30'years I just don't remember that detail.
Just release the oxygen sensor wires & put them in their own separate connector. And you should always add a generous amount of dielectric grease.
 
Awesome, going to do just that.

Lonewolf: The light went on about 2 weeks ago, not sure if it would tell me anything now. But that may be because I don't know how to find out error codes, it's just one light that says "engine".

I used to hit it with carb cleaner once a month or so last year when i was having problems, and it slows down quite a bit when I do that, but i stop before it sputters out.

A neighbor said we can use his pressure gauge and check the pistons pretty soon, so that's next. He also mentioned the timing belt, I can't say when it was last replaced - definitely not within the last 3 to 4 years. These are all great tips, thanks a bunch for the help
 
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