Car Question

Jeff Oliver · Apr 16, 2014

I have a 1973 Plymouth Scamp when a slant six in it. I am trying to get the motor running right and have gotten real close but here is what is is doing and hopefully someone can help me.

We rebuilt the carb as it run rough and didn't get the timing set right. It would idle fine and run good but when you started to take off it would hesitate and or die. Adjusted timing and got that fixed kinda. Now when you first crank it and drive it it will run fine. However when you turn it off for a few minutes ) getting gas , food,etc. and start it up and take off it goes back to doing the same thing along with running like it is surging or has bad gas.

Any suggestions one where to start looking?

Anonymous-0 · Apr 16, 2014

try fuel filters ,,also think aboutgoing to electro ic ig

ericlb · Apr 16, 2014

have you checked the fuel pump pressure? also when you go around a sharp corner does the car try to die? if so , the accelerator pump in the carb is shot, did you replace that when you rebuilt the carb? some kits dont come with that piece and you have to get it extra also check the float setting in the carb, the specs should have been on the sheet that came with the carb kit, also make sure the float isnt leaking, if its taking on gas, it will change its heght. another thing to check for is a vacume leak somewhere that will make it run rough,let us know what you find, hope this helps

JRSutton · Apr 16, 2014

Does sound a little like vapor lock.

Make sure your fuel line is well away from the exhaust manifold, or shielded properly. Winter gas is more volatile than summer gas - so ... otherwise I'd say it's a little too cold yet for that problem.

But easy enough to see if your gas line is near the exhaust.

Hard to guess what else on a 73 without knowing more. How good are the plug wires? Points? How old is the coil?

If the ignition parts are all relatively new and solid, I'd think about cleaning out the carb thoroughly.

A problem like that's tough because it sounds like there's a pattern. But probably not enough of one to be sure. Does it ALWAYS run rough after stopping it - or did it just happen to run rough a few times after stopping it.

Getting the engine wet through rain or puddles could cause it if it's got bad plug wires - but you might not have yet made that connection to the times it has happened.

Sprint 6 · Apr 16, 2014

Does it have the electronic ignition with the control on the fire wall? I know Chrysler was one of the first to have electronic ignition. Anyway, those controls are known for causing all sorts of weird driveability problems. A lot of them were changed back to points.

Anonymous-0 · Apr 16, 2014

It may not sound right but years ago we changed points and condenser on a 383 and it did the same thing. Went back to the old condenser and it ran fine. Worth a try

Keith Molden · Apr 16, 2014

Kinda sounds like a choke problem to me. Those old dodges were prone to have the choke stick a little. If memory serves me correctly you can adjust it. Just my thoughts, Keith

Jeff Oliver · Apr 16, 2014

Thanks for the ideas everyone. As far as I know when they rebuilt the carb the pump was done also. it does sound like vapor lock to me also but its weird in that it won't do any of this until you turn it off and then back on. It has happened several times not just once so it is ongoing. If I remember right the plugs and wires are new ( think dad had that done.) Not sure about electronic ignition but I will check and see. And coils are cheap in comparison so might just change it anyway if it is older. heck I bought a brand new on one time that was bad, soooo.

The fuel pump is an OEM one. WE had put an electric one it but went back to the OEM style after having problems with the electric ones. I'll try to look tonight and see and post back.

Again thanks everyone! I knew this was the place to come to get good information

J. Everett · Apr 16, 2014

This carb. was noted for neoprem floats that would sink, especially if you used ethonal gasoline. Typical symptom is engine dies while turning a sharp corner, and also seems to not re start after warm/ vapor lock symptoms = low float level.

Dick2 · Apr 16, 2014

Also check for a vacuum leak somewhere in the system.

Steve@Advance · Apr 16, 2014

Does the distributor have a vacuum advance? If not, it has electronic timing. If it's what I'm thinking it has, "Lean Burn Ignition" good luck ever getting it to run right!

If you have a timing light, take a look at the timing. You'll find it's all over the place, jumping back and forth with no rhyme or reason.

Never did it, but suspect you could go with an earlier electronic distributor with mechanical/vacuum advance and get some improvement.

john *.?-!.* cub owner · Apr 16, 2014

That model would have an accelerator pump in the carb, the hesitation sounds like a problem with it.

k6zrx · Apr 16, 2014

My '72 with electronic ignition and a 360 did something like that and it was the coil.

Josh

old-9 · Apr 16, 2014

Accelerator pump. Take the air cleaner off and look if it pumps a stream of gas or not.Very easy check. I had a problem and had to go to a leather piston.

luck joe

jerrybigrig · Apr 16, 2014

I'm with Steve ...timing issue eather ignition or cam i think some timing gears had nylon or plastic on gears and after time would fall apart and loose cam timing

320B · Apr 16, 2014

Does it crank over slow when starting it hot. Could be to much timing or a bad connection at the starter. Also the ballist resistor is the most common part to fail on the old dodges. It will cause all kinds of weird issues. Is it a 225 slant 6 or the smaller one.

Pops1532 · Apr 16, 2014

Check the fuel pressure and check the volume the fuel pump puts out cold.
Warm the engine up and check the fuel pressure and volume again.
The results from those tests should give you an indication of the condition of the fuel pump.

Has the car been sitting? Could be there is rust plugging the screen on the pick up in the gas tank. Can you rig up a portable gas tank to rule out a plugged screen in the car's tank?

Were the parts in the carb kit ethanol compatible?

Ignition coils can sometimes be problematic when they're hot. Coils mounted vertically didn't have as many problems as those mounted horizontally.

If your ignition timing is jumping around it could be worn bushings in the distributor.

I don't think it's a vapor lock issue. In my experience, when vapor lock occurs the engine either won't start at all, or if it does start, it will die and not restart. That usually doesn't happen until you're in the middle of an intersection of two highways. :wink:

Don't throw parts at it. Diagnose the problem, then replace what needs to be replaced.

IH2444 · Apr 16, 2014

The timing and timing advance is easy to check with a timing light.

My vote is the choke. Is it a 1 or 2 bbl?

I put 300k on a slant six. Never had the top or bottom off of it.

fixerupper · Apr 16, 2014

I lean towards Old9's suggestion. The choke pulled off kind of early in those to keep from overheating the cat converter. If the accelerator pump isn't working it will act lean and die till it is completely warmed up. I am a strong ethanol supporter but in those years ethanol would wrinkle the accelerator pump up like a prune. I ran Chrysler products from 1973 till into the 90's and they all had touchy chokes. Carter and Holley carbs tended to be more ethanol sensitive in that era. Jim

IH2444 · Apr 16, 2014

they rebuilt the carb. New kits have ethanol resistant parts in them.

The question is it loading up on fuel or starving?
Black smoke when the problem is there?

Car Question

Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Member

Member

Well-known Member

Well-known Member

Well-known Member

Member

Well-known Member

Member

Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Similar threads