1973 Plymouth Scamp accelerating/braking issues, please help

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cer1284

cer1284

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Hi Guys,
Wondering if you guys can help with the issue I'm having.. I'm having trouble dialing the issue down but I'll shoot out the symptoms and let me know what you think?

Whenever I start my scamp, it usually fires right up with two pumps and a start, no problem. When I take it for a cruise it runs strong until I punch the accelerator too much too hard and it stalls on me. I can usually fires it right up again, but soon after it starts dying while idling, and can hardly make it home. On a similar but separate note, when approaching a stop sign and stopping too hard too soon, the car shuts off again.. again, making it impossible to go anywhere.

Wondering if you guys can point me in the right direction... :prayer:
 
Have you done anything else to the car? Any car history? What is the state of tune plugs/wires/fuel filter. Does it blow black when you are accelerating? I would start at the carb. I have seen needle valves stick after the car has sat awhile and the fuel evaporated cause similar behavior. Also is the choke staying open? I have had them slap shut going down the road and that is no fun. Most (95%) part store rebuilt carbs have issues of one kind or another.
 
cer1284 said:
Hi Guys,
Wondering if you guys can help with the issue I'm having.. I'm having trouble dialing the issue down but I'll shoot out the symptoms and let me know what you think?

Whenever I start my scamp, it usually fires right up with two pumps and a start, no problem. When I take it for a cruise it runs strong until I punch the accelerator too much too hard and it stalls on me. I can usually fires it right up again, but soon after it starts dying while idling, and can hardly make it home. On a similar but separate note, when approaching a stop sign and stopping too hard too soon, the car shuts off again.. again, making it impossible to go anywhere.

Wondering if you guys can point me in the right direction... :prayer:
Click to expand...

Sounds a lot like it probably has a carburetor problem to me.

I'd try a rebuild on the carb and a general tune-up (new spark plugs, spark plug wires, new cap and rotor, fuel filter, air cleaner element, and pcv valve.)

That might make a new car out of it!!!

Let us know! Pay particular attention to the setting and condition of the carburetor float (how much it weighs, and getting it set to the correct level) when you do the carb rebuild. That stuff is critical to good driveability.

A valve adjustment couldn't hurt...

Good luck!:cheers:
 
mcnoople said:
Have you done anything else to the car? Any car history? What is the state of tune plugs/wires/fuel filter. Does it blow black when you are accelerating? I would start at the carb. I have seen needle valves stick after the car has sat awhile and the fuel evaporated cause similar behavior. Also is the choke staying open? I have had them slap shut going down the road and that is no fun. Most (95%) part store rebuilt carbs have issues of one kind or another.
Click to expand...

I purchased my scamp a few months ago to get in working condition and give to my old man. When I first checked it out, it started fine but I noticed (after checking the oil levels) that the oil smelled like gas, the car need a new battery, new alternator, and fuel pump.

I manage to replace the alternator, the fuel pump, spark plugs, distri cap, battery, and thats about it. I got it running pretty solid but more recently it started acting up. The carb was replaced before I purchased so I crossed that out of the equation, maybe that was a mistake.

After the car starts to idle rough and almost turn off, i press on the gas for a minute, and idle it a little high, after about a minute it feels/sounds like something jams into place and the car runs fine for a brief moment..
 
Bill Dedman said:
Sounds a lot like it probably has a carburetor problem to me.

I'd try a rebuild on the carb and a general tune-up (new spark plugs, spark plug wires, new cap and rotor, fuel filter, air cleaner element, and pcv valve.)

That might make a new car out of it!!!

Let us know! Pay particular attention to the setting and condition of the carburetor float (how much it weighs, and getting it set to the correct level) when you do the carb rebuild. That stuff is critical to good driveability.

A valve adjustment couldn't hurt...

Good luck!:cheers:
Click to expand...

THanks!!! I'm going to take a look at the carb today. Is there a good replacement carb you recommend in case I have to go that route?
 
Ditto on likely the carb. My 69 Slant w/ Holley 1920 acted like that for many, many years, despite many intake and engine changes and even a new long block. Finally tried a ~4th carb and it ran like a dream. The others must have made it idle lean. I now have a slant again, a 64 w/ Carter BBS and it idles so smooth you can hardly tell the engine is running. The BBS appears more approachable (judging by the manual) with all internal parts visible, unlike the 1920 w/ sealed metering block, but I haven't opened it up yet. Some people like the Holley 1945. A few like the 1920, but must have lucked out (like my last one). I have read no complaints of a Carter BBD on a 2-barrel manifold.
 
This sounds as if engine is running lean at idle.
Check fuel bowl for dirt & blow out internal passages, adjust float for correct fuel level, look for vacuum leaks and fix as necessary. Adjust idle circuit using vacuum gage to highest vacuum, and idle speed, than adjust idle rpm by screw that moves throttle plate aka idle speed adjustment screw.

Secondly, if this unit is a remanufactured carburetor, chances are good you may never get it to work properly.
 
I think you may have a float problem. They get saturated then heavy then they're no good. Mine ran a lot better after I replaced it. It's cheap insurance and only takes a few minutes to replace.
 
THanks for your help guys!! the Holley 6594 carb is running very rich after another attempt at mixture adjustment.. going to attempt again tomorrow. I'm looking for a rebuild kit but can't find one. Should I just drop this carb and get into a 1920?
 
cer1284 said:
THanks for your help guys!! the Holley 6594 carb is running very rich after another attempt at mixture adjustment.. going to attempt again tomorrow. I'm looking for a rebuild kit but can't find one. Should I just drop this carb and get into a 1920?
Click to expand...

Just realized the 6594 is a 1920 ha
 
Tune-up parts and technique suggestions in this thread. Carburetor operation and repair manuals and links to training movies and carb repair/modification threads are posted here for free download. "Remanufactured" carburetors are junk. Buy a good-quality rebuild kit; I like the ones from www.daytonaparts.com best; they have a better inlet needle/seat design less prone to flooding than others. Install a new float, Walker #100-14; the float is nitrophyll (foam) and over the years they absorb fuel and no longer work right. Make sure to use the correct thick (11/32" or so) insulating carb base gasket.

Find the one and only hose that connects to the distributor and make sure the other end of it goes directly to the carburetor without stopping at the widget on the passenger side of the firewall (if your firewall widget, a primitive emission control device known as an OSAC valve, is still hooked up -- follow its other hose to the carburetor, then bypass it by connecting directly from carb to dist).

Make sure your manifold heat control valve is free, not stuck, and is operating correctly. You may want to do the Fuel line mod.

Try a base ignition timing setting of 5° BTDC (with engine idling at 750 rpm, hose disconnected from distributor and plugged).

Keep on top of the valve adjustment.

Also you will want to get the three books described in this thread as soon as you can.
 
wjajr said:
This sounds as if engine is running lean at idle.
Check fuel bowl for dirt & blow out internal passages, adjust float for correct fuel level, look for vacuum leaks and fix as necessary. Adjust idle circuit using vacuum gage to highest vacuum, and idle speed, than adjust idle rpm by screw that moves throttle plate aka idle speed adjustment screw.

Secondly, if this unit is a remanufactured carburetor, chances are good you may never get it to work properly.
Click to expand...

Can you find a way to get your fonts any smaller?
 
Here's an update guys!
So I tuned up the car, replaced points/plugs, got it timed, replaced the carb with a nice rebuilt Holley 1920, replaced the vacuum hose, and fired her up. I'm sorry this is so brief but I'm eager to get to my next issue.. Once I finished she fired right up, I took her for a 15 minute spin to get the engined warmed up enough to adjust the carb. Adjusted the carb and continued to drive her around to check for any other issues.

The car started to idle really rough after 15 minute of driving then started stalling. I talked to my old man and did a little research in the forums and narrowed down the tough idle and stalling to the ignition coil. From what I've picked up they share similar symptoms.

So this morning I replaced the ignition coil with a BWD E30 Ignition Coil Part #E30 SKU:9790777 and started the car, she started strong and right away and off we went. I tried everything I could to make it stall again and couldn't. She was running very nice!! On my way home she started idling rough again, and stalled on me a couple of times. I made it home just fine. I'm doing a bit more research now and can't find anything.. Wondering if you guys have any advice.

I apologize for my lack of proper terminology and detail. I'm learning as I go along.

Thanks
 
green1 said:
Can you find a way to get your fonts any smaller?
Click to expand...

Tip: If (as the reader) you put your cursor somewhere (anywhere) in the message, press and hold the "ctrl" key down while rotating the "scroll" wheel on your mouse, it will make the font you are reading larger (or smaller, depending on which way you rotate the scroll wheel.

That works with my Internet Explorer IE-7; dunno if it works on other browsers.
 
Hey guys, I have another update to my car issue. The scamp is running great for the first hour, then begins to die again. I noticed after replacing the distributer, she fired right up, ran like a dream for about an hour. Then went to gas her up, and couldn't get her to start again.. After several attemps she finally kicked and I was able to get her home. Parked it in the garage, the next day she fired right up again, and ran great for another hour. Haha. Could this be an electrical issue? or quite possibly a transmission problem?

I replaced..
Carb - Holley 1920
Fuel Pump
Fuel Filter
Ignition Coil
ICM (Ignition Control Module)
Voltage Regulator
Cap/Rotor/Cables
Spark Plugs
Ignition Coil (Disconnected Resistor - is it necessary to have it grounded?)
Point/Plugs
Timing 5° BTSD
Distributer

Thanks for checking this out fellas!
 
It still sounds like either a heat-related ignition issue wherein an ignition component failing when it gets hot, or a fuel contamination issue—trash in the fuel tank gets sucked against the fuel pickup screen as the engine runs, eventually blocking it off. Stop the engine, suction goes away, trash floats down off the fuel pickup screen. Eventually enough trash drifts away from the screen that the engine will start and run again.

Unless it's a failing connector at the bulkhead disconnect -- have you checked/cleaned? -- it's probably not an electrical issue because you've replaced all the suspect components (coil, ICM, and the pickup in the distributor would've been swapped when you replaced the distributor as a whole).

The next time the engine stops and won't restart, remove the air cleaner lid and operate the throttle by hand as you peer down the carburetor. If you see a shot/squirt of fuel emitted from the sidewall of the carburetor throat towards the centre of the carburetor throat, then you're not lacking for fuel supply and my clogged-screen guess is probably wrong. But if you see no such shot/squirt, you've got fuel supply problems, probably as described above. If you do have fuel, the next test is to check for spark by removing the ignition coil cable from the centre tower of the distributor cap and holding it (by the wire insulation) so its metal end is about 3/8" away from the cylinder head casting while someone else turns the key to the "Start" position for you. If you see sparks flying from the end of the coil wire to the cylinder head, you've got spark. If not...time for more electrical diagnosis.

So why did it run so well after replacing the distributor? Perhaps because enough time went by while you were doing so for the crud to float off the fuel pickup screen.

possibly a transmission problem?
Click to expand...

No.

I replaced..
Carb - Holley 1920
Click to expand...

Replaced with what? If a "remanufactured" carburetor, you've probably bought yourself more problems, not fewer.

Ignition Coil (Disconnected Resistor - is it necessary to have it grounded?)
Click to expand...

This doesn't make sense as written. Why did you disconnect the resistor? And what is it you think should be grounded?

Point/Plugs
Click to expand...

Your car doesn't have points.

Timing 5° BTSD
Click to expand...

BTDC.
 
"When I first checked it out, it started fine but I noticed (after checking the oil levels) that the oil smelled like gas, the car need a new battery, new alternator, and fuel pump"

I've read here about a fuel pump failure (diaphragm?) that allows gas to get into the oil, so you may have a diaphragm that works intermittently and has fluctuating fuel pressure.

Just a thought.
 
…but the fuel pump is on the list of replaced parts.

(cer1284 ,you have changed the oil and filter since replacing the fuel pump, right?)
 
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