Had to tow the 65 home :-( - Page 2 - Impala Tech
Troubleshooting Diagnosing problems

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post #26 of 44 (permalink) Old 08-13-2016, 02:08 PM Thread Starter
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No starting issues. Starting fine, hot or cold. I can't work on it until next week, I'll report back.

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post #27 of 44 (permalink) Old 09-03-2016, 07:13 PM Thread Starter
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Finally found some time to work on the 65. Removed the points that I installed last tune up (Blue Streak, condenser built in), and swapped in a Pertronix 1181LSC. Wired it carefully according to the instructions. Unfortunately, this didn't fix things. It's actually worse. It will crank, and catch, then die as soon as I let off of the start setting on the key. I'm sad and frustrated. Going to get some help tomorrow and check spark on #1. Then, swap in my old (pre tune up) points.

One step forward, two steps back.

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post #28 of 44 (permalink) Old 09-03-2016, 09:40 PM
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Quote:
Originally Posted by jayoldschool View Post
Finally found some time to work on the 65. Removed the points that I installed last tune up (Blue Streak, condenser built in), and swapped in a Pertronix 1181LSC. Wired it carefully according to the instructions. Unfortunately, this didn't fix things. It's actually worse. It will crank, and catch, then die as soon as I let off of the start setting on the key. I'm sad and frustrated. Going to get some help tomorrow and check spark on #1. Then, swap in my old (pre tune up) points.

One step forward, two steps back.
Isn't that new symptom just that the pertronix requires a constant 12 volt signal? (not via stock resistive wiring)

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post #29 of 44 (permalink) Old 09-03-2016, 09:54 PM
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Have you been able to verify fuel pressure under these various conditions?
I'm wondering if the fuel pickup sock could be clogged, or something limiting your fuel pressure?

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HOW A NOVICE REBUILDS A 66 IMPALA CONVERTIBLE:
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post #30 of 44 (permalink) Old 09-04-2016, 08:02 PM Thread Starter
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BA, thanks for the push on the 12v feed for the Pertronix. There were many reports of it working fine when wired to the resistance wire, so that's the way I tried it.

Progress today, however. I made a jumper from the battery to the coil+ (where the Pertronix pos lead goes), and the car started right up. Ok, I now know that the cloth resistance wire would not supply sufficient voltage once I released the key. Fabbed up a nice big gauge lead, and connected it to the switched IGN feed on the fuse box and the +coil lead. Ran it nicely through the factory harness mounts. Started it up, let it warm up, and took it for a short drive. The good news is that the car runs, and runs much stronger than before. Bad news is it is still breaking up when at cruise speed (45-60mph) and I get on the gas.

Next step will be to reset the timing, and check the idle speed and mixture. Hopefully that takes care of things. In addition to the (now replaced points), I did fresh plugs/cap/rotor last tune, but didn't do wires. Maybe I should change them out...

Thanks for the discussion, guys. I appreciate it.

Still might be bad gas. I put 3/4 of a tank of 93 no ethanol in it on the way home from work right before it started giving me problems. It was from a different station than I normally use. Maybe I should dump in 20L of fresh high test from my usual place. I initially suspected gas/gas delivery, that's what led me to the pump replacement.

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post #31 of 44 (permalink) Old 09-05-2016, 08:46 AM
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I don't know what kind of alternator you have (DN, SI, or CS) but the factory original was nothing more than a trickle charger for the battery. It didn't put out enough power below 3,600 RPM to power much more than the radio and the ignition. If anything else was drawing electrical power the GEN light would glow dimly to bright as the battery is discharging instead of charging.

Low voltage has a difficult time overcoming resistance. If you have bad spark wires the voltage will stay in the wire as it is the path of least resistance. As your RPM picks up the alternator starts to make power if you have a SI or and older DN alternator that raises the voltage to the coil and as a result increases the voltage to the plugs. The added voltage can over come the insulation that cracks and shrinks with age causing power that should be going to the plugs to leak away to the block.

If you have a one wire alternator (the CS version of the Delco-Remy alternator then you have full rated power just above idle (2,200 RPM). The rated power starts at 105 Amps which is about two to three times the rated power of a DN alternator.

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post #32 of 44 (permalink) Old 08-27-2017, 07:44 PM Thread Starter
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Bumping this thread because I have updates. After I did all the work, the Impala was starting, idling, and accelerating great. Unfortunately, it had to come home on the truck again. Same symptoms. Bucking at speed, then eventually, just dying when any acceleration was attempted.

Today, I got to work on it again. Took it out for laps on the country roads around my house. Accelerated hard, cruised at up to 70mph. Eventually, it began to cough. I brought it home, and plumbed up a temporary gas tank to feed the fuel pump. Thought this would rule out a problem with the tank or lines. Car behaved the exact same. As a last resort, I pulled the stock fuel filter from the carb inlet. No change. Still stumbling/coughing on acceleration at cruise speed.

It has to be the carb. I think the floats must be hanging UP. I'm going to rebuild it. I only use non-ethanol 91 octane, so I hope this clears things up.

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post #33 of 44 (permalink) Old 08-27-2017, 08:17 PM
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Could be a bad pump also. Rubber doesn't behave as you might expect when it is heated and cold rubber with a hole in it behaves differently than hot rubber with a hole in it. To isolate fuel lines tank and fuel pump try experiment again with an electric fuel pump temporarily wired into car. If it runs great and you have eliminated the tank and fuel lines you are left with only one suspect.

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post #34 of 44 (permalink) Old 08-27-2017, 11:02 PM Thread Starter
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I put a new pump on it, and just today ran it on an auxiliary tank to eliminate the stock tank/sock/lines as the problem. No change.

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post #35 of 44 (permalink) Old 08-31-2017, 12:00 AM
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Years ago, I had the plate that holds the points gum up at the pivot point (dried up oil). Easy to check. Take the distributor cap off and move the vacuum advance rod. It should return as soon as you let it go. Easy to fix. Squirt brake cleaner on the pivot point while moving the rod back-and-forth.

Tom

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post #36 of 44 (permalink) Old 08-31-2017, 07:09 PM Thread Starter
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I will double check that. I did verify the operation of the vacuum module when I did the Pertronix.

I'm going to put a fresh set of plug wires on it before rebuilding the carb, too.

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post #37 of 44 (permalink) Old 09-01-2017, 02:06 PM
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This is turning into quite the long-term soap opera JayOldSchool!

HOW A NOVICE REBUILDS A 66 IMPALA CONVERTIBLE:
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post #38 of 44 (permalink) Old 09-01-2017, 03:37 PM Thread Starter
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Yes, it has been crazy! This car has been the most reliable car ever, for two decades. The only thing I ever did to it was replace a voltage regulator after boosting it one spring. I need to get it back to that condition again. I miss driving with the top down! I will have more space and time, I just sold one of my other classics this morning.

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post #39 of 44 (permalink) Old 09-01-2017, 08:45 PM
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Have you checked the grounds on the motor?? I had a Buick GN that drove me crazy with similar issues. Any issues with headlights dimming, gas gauges acting weird, etc. ?????

Brian

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post #40 of 44 (permalink) Old 09-02-2017, 10:45 AM Thread Starter
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No ground issues, the car is 100% rust free.

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post #41 of 44 (permalink) Old 09-02-2017, 09:50 PM
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I keep re-reading the thread when there are updates - I re-read old posts - looking for clues.

I see up above you put .... "Still stumbling/coughing on acceleration at cruise speed".

Since you've eliminated so many possibilities - I happened to think of one that would fit that description that I think you have NOT checked.

Have you checked/replaced the carburetor accelerator pump? Maaaaybe even just sitting in the driveway, in Park, engine running, Hood UP and winging the throttle heavily to ensure that *both* nozzles are squirting fuel. (I forgot if you have a Holley or Edelbrock)

HOW A NOVICE REBUILDS A 66 IMPALA CONVERTIBLE:
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post #42 of 44 (permalink) Old 09-02-2017, 11:43 PM Thread Starter
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The accelerator pump is working fine. Good squirt when throttle opened. It will get replaced anyways when I rebuild the carb. Next week, I have to deliver the Cadillac I sold yesterday. I'm starting to suspect a weak secondary spring that is allowing the secondaries to pull open under high vacuum. I read about this possibility on a carb site. Hopefully the rebuild kit has one.

I really appreciate you guys still thinking this one through with me. I'm slowly crossing off all the possible causes... really slowly. I did reupholster the rear seat a couple weeks ago just to stay motivated!

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post #43 of 44 (permalink) Old 09-03-2017, 08:19 PM
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Quote:
Originally Posted by jayoldschool View Post
I did reupholster the rear seat a couple weeks ago just to stay motivated!
If it was me I would have re-upholstered the seat first, and then found that the engine started playing up - and I'd be left trying to figure out how in the hell that happened.....
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post #44 of 44 (permalink) Old 08-30-2018, 11:45 PM Thread Starter
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Everyone loves an update... so here it is.


I found the problem.


Since I had done everything else, the only thing left to do was to rebuild the carb. Factory date code tag still on there, ordered up the kit. Pulled the carb, immediately saw the cause of the issue. The base gasket had failed on one corner, allowing moisture and rust to accumulate on one small area. I believe that once hot, unmetered air was being pulled below the carb causing an ultra lean condition when the throttle was opened. It was obvious that this had been developing for a long time. If you know 4GCs, you know the recesses on the base, one was all full of rusty/carbon/crap.



I could have simply cleaned up the base, and re-gasketed, but... I had the carb off, so... I rebuilt it anyways. It was spotless inside. Cleanest carb I've ever done. I can't say enough about using non-ethanol gas. Zero deposits inside, non of that white powdery buildup that you see from ethanol gas. Set the floats, reinstalled. Nice fresh carb base gasket, made sure the mounting flanges were clean and square for a good seal.



Verdict? Car is driving perfectly. Lots of power, all the way through the RPMs. I started with a couple mile drive around my house, then a 15 miler to town, then a 40 mile to work and back. All is good. And I have a new fuel pump, and electronic ignition, lol.


Bottom line? Once you've done everything else, the answers get easier to find.
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