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Username Post: Shudder under load and dying on stop        (Topic#365434)
Aquavit750 
Newbie
Posts: 11

Reg: 11-28-17
06-05-21 10:41 AM - Post#2821169    

1966 impala 283 3-on-the-tree. Starts to shudder around 2200 rpm. The feeling was as if there was water in the distributor cap. Checked fuel pump. It works. Started to replace electrical components. Wires, plugs, coil even a new distributor as the previous one was 55 years old. I still get popping and shudder. Now the car dies at idle. Can anyone help me pin down what I’m missing. Thanks for any help.

J-Dub


 


brasii 
Contributor
Posts: 175

Loc: FRANCE
Reg: 11-09-07
06-05-21 01:48 PM - Post#2821175    
    In response to Aquavit750

Can you put a little video ??

impala 66 convertible


 
toro455 
"6th Year" Silver Supporting Member
Posts: 581
toro455
Loc: Western NY
Reg: 06-15-02
06-05-21 09:21 PM - Post#2821194    
    In response to Aquavit750

Just a guess but it could possibly a needle and seat issue or a float causing flooding.



 
japete92 
"7th Year" Silver Supporting Member
Posts: 1639
japete92
Loc: No. Virginia
Reg: 01-18-13
06-06-21 05:24 AM - Post#2821202    
    In response to Aquavit750

  • Aquavit750 Said:
1966 impala 283 3-on-the-tree. Starts to shudder around 2200 rpm. The feeling was as if there was water in the distributor cap. Checked fuel pump. It works. Started to replace electrical components. Wires, plugs, coil even a new distributor as the previous one was 55 years old. I still get popping and shudder. Now the car dies at idle. Can anyone help me pin down what I’m missing. Thanks for any help.



I'm not 'clear' on what you have done so far, but:

Could simply be in dire need of a full tune-up. Points, plugs, rotor, distributor cap , and an ignition timing check/re-set. AND, replace fuel filter.

A cracked distributor cap can allow moisture to enter, but that usually does not allow the engine to run at all (until it dries, and then it will run fine).

I'd start with those because there is no 'waste' there. Next would be plug wires (unless they visually looked bad; then they would be in step 1).

Coil? Not causing your problem. But, they are not expensive and IF you just want to replace it, get one that is oil cooled (not epoxy).

AFTER ignition is verified to be good, adjust carb fuel mix (if necessary).

I'm not going to assume you have no experience with tuning a 'points' system, so I'll skip any 'how to' stuff. There IS a process that requires following to get it right. Refer back if necessary.

Pete





 
bobb 
Super Senior Member
Posts: 5806

Loc: paradise
Reg: 09-05-03
06-06-21 09:42 AM - Post#2821218    
    In response to Aquavit750

what kind of distribiter did you get? you may want to do a compression test. do you have headers?

70 L camino, grampa engine, g-force 5 spd, road rage suspension. Pray first before all else fails.


 
Oshawa65SS 
Frequent Contributor
Posts: 1049

Age: 61
Loc: Grande Prairie AB & N...
Reg: 09-22-14
06-06-21 12:33 PM - Post#2821225    
    In response to Aquavit750

I'm thinking carb issue but pull the fuel sender/pickup and see if the tank is rusty or there's water, and that the filter sock looks good.
Check all the vacuum hoses too.

Ryan

65 Impala SS Evening Orchid convertible 283 2V with Powerglide and 10 bolt 3.08 open by PO, originally 3.36
Build date Dec. 21 '64 Oshawa


 
steve65 
"6th Year" Gold Supporting Member
Posts: 998
steve65
Age: 63
Loc: New Westminster BC
Reg: 09-25-13
06-06-21 02:23 PM - Post#2821235    
    In response to Oshawa65SS

I'm with Ryan on one. Check the fuel filter sock on the sending unit. And get a vacuum gage and see what you have at idle and as the RPM goes up. I'm guessing a vacuum leak has opened up.
Steve

Steve Duncan
66 Impala 2dr Coupe
Not sure of color yet
work in progress



 
Aquavit750 
Newbie
Posts: 11

Reg: 11-28-17
06-06-21 04:44 PM - Post#2821244    
    In response to japete92

Thanks Pete. So what I’ve replaced so far were the plugs, wires, distributor, cap, points, rotor and coil. I checked the carburetor float and seat today it is fine. I had it all over town Friday night and Saturday morning it warmed up about halfway, died and hasn’t started since.

J-Dub


 
toro455 
"6th Year" Silver Supporting Member
Posts: 581
toro455
Loc: Western NY
Reg: 06-15-02
06-07-21 03:46 PM - Post#2821305    
    In response to Aquavit750

If it's happening only when hot I wonder if it could be vapor locking. I've knock-on-wood never had that issue so I'm not certain of other symptoms.

How long have you had the car without issue?

I had a strange issue which resulted in random stalling when a fuel line (soft line) was pinched above the tank. It was strange but it would run fine and then just die.





Edited by toro455 on 06-07-21 03:47 PM. Reason for edit: No reason given.

 
japete92 
"7th Year" Silver Supporting Member
Posts: 1639
japete92
Loc: No. Virginia
Reg: 01-18-13
06-08-21 05:35 AM - Post#2821333    
    In response to Aquavit750

  • Aquavit750 Said:
Thanks Pete. So what I’ve replaced so far were the plugs, wires, distributor, cap, points, rotor and coil. I checked the carburetor float and seat today it is fine. I had it all over town Friday night and Saturday morning it warmed up about halfway, died and hasn’t started since.



A few simple fuel system 'checks' that I'd perform next:

Replace the fuel filter. They are too inexpensive to 'check'.

Fuel pump performance 'fluctuates' on a 'dying' pump; often producing insufficient pressure to accommodate rpms. 'Dead'; the car won't start. Check the pressure (it should be around 6-7 psi).

As already suggested (and especially if the the car has ever 'sat' for a long period of time), check the fuel 'sock'.

Just info:

If any of the above resolve your problem, don't declare victory yet.

IF the car has 'sat' for along time any time in its life; there's a good possibility the gas tank's interior is corroded and/or 'coated' with all kinds of nasty gunk. Particles slough off, get into the fuel, and clog up anything/everything. Some particle are so 'fine' they will pass thru a filter and 'clog up' anything down stream of it (carb).

So, there may be a period of initial 'success' but as time passes, the systems may return. AND you have to 'clean up' EVERYTHING again.

Some folks 'clean/flush' a gas tank. Because a brand new one costs about $200 (Spectra; a Canadian Co.), I would replace rather than 'clean'.

Pete











 
Impalas4ever 
Newbie
Posts: 40

Reg: 09-24-20
06-11-21 08:57 PM - Post#2821504    
    In response to Aquavit750

Can you please explain the popping. When does it occur? Through the carb? Exhaust? On acceleration, or deceleration, at a steady RPM? How many miles on the motor? Is the motor stock? When did this issue begin, was it running fine one day and parked then run bad? Did it happen when accelerating hard? Stop replacing items. Diagnosing is your answer, not throwing money at it.



 


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