[Jerry H.]

Need some help. I got out in my 65 GP today for a nice leisurely drive. Car is running great. When I turned the AC on I starting noticing a little hesitation, kinda like a miss, but not consistent. From about 40-60 (that's the fastest I got) I would feel a little miss, but only with the AC compressor on. Any ideas?

[Navy Horn 16]

Turn off the AC and roll the window down.

[Gary H]

Could be that the extra electric used by the A/C and blower fan is lowering the voltage too much and causing an ignition miss. I'd check voltage to the coil with and without the A/C on and see if it's dropping too much. Is it still points or is it electronic conversion?

[shaker455]

X2 gary H.
I can personally vouch seeing a got a stock 67 GP.
External voltage regulators are spotty at best with keeping stable volts on demand.
Also if that's a Factory Carter carb the leather accel pump it maybe time.
Clean the carb up and new pump.

[77 TRASHCAN]

Make sure of all grounds. I know you just detailed the engine. Make sure paint isn’t insulating any grounds..... if you haven’t already.

[AJ-]

Check voltage at battery to see if it's charging (voltage higher running than not running). Could be running on battery alone.

[steve25]

It does not take long for today's fuel sitting in a Carb over the winter to go bad!

If your Alternator is outputting atleast 12.9 volts at idle with the headlights on then my money's on the crab having a somewhat clogged fuel passage in the cruse circuit, or you have a vacuum line that's dry rotted and no longer sealing on a nipple well.

[Jerry H.]

Originally Posted by Gary H

Could be that the extra electric used by the A/C and blower fan is lowering the voltage too much and causing an ignition miss. I'd check voltage to the coil with and without the A/C on and see if it's dropping too much. Is it still points or is it electronic conversion?

Still points, but new transistorized voltage regulator.

[Jerry H.]

Originally Posted by steve25

It does not take long for today's fuel sitting in a Carb over the winter to go bad!

If your Alternator is outputting atleast 12.9 volts at idle with the headlights on then my money's on the crab having a somewhat clogged fuel passage in the cruse circuit, or you have a vacuum line that's dry rotted and no longer sealing on a nipple well.

It sat in my heated garage with Stabil in the tank. Newly rebuilt alternator. It shows just a needle with the the left of center on the volt gauge. Replaced all the vacuum lines and double checked the grounds with new ground straps plus an additional ground.

If it's in the carb shouldn't it do it all the time?

[mgarblik]

You said the issue was only with the AC on? So I would verify the AC system early in your diagnosis. You didn't mention if the car had automatic climate control? I think 65 was the first year for the option. Manual AC or ATC would both use a POA valve and not a cycling clutch, but if for some reason the clutch were engaging and dis-engaging, it would feel like a miss. Is the AC system working OK and cooling as it should?

[steve25]

Good point in the above post!

[Jerry H.]

Originally Posted by mgarblik

You said the issue was only with the AC on? So I would verify the AC system early in your diagnosis. You didn't mention if the car had automatic climate control? I think 65 was the first year for the option. Manual AC or ATC would both use a POA valve and not a cycling clutch, but if for some reason the clutch were engaging and dis-engaging, it would feel like a miss. Is the AC system working OK and cooling as it should?

Yes, only with the air on. No ATC, but the AC system has recently been completely gone through bypassing the original push button switch and converted to R 134. I'll check if the compressor is cycling when the weather opens up.

["QUICK-SILVER"]

Originally Posted by Jerry H.

It shows just a needle with the the left of center on the volt gauge.

This an amp guage showing a slight discharge?

Clay

[Jerry H.]

Originally Posted by "QUICK-SILVER"

This an amp guage showing a slight discharge?

Clay

The gauge in the center of the three.

["QUICK-SILVER"]

Originally Posted by Jerry H.

The gauge in the center of the three.

That's a ammeter (amp-meter). Needle left of center is discharge and/or running off the battery instead of the alternator.




Need to get this cleared up
Clay

[aceaceca]

I suggest that if the car did not miss or hesitate prior to "the complete air conditioning system was gone through", then something could be amiss with the AC work.
Why was the original push button switch bypassed? And, bypassed onto what? Not sure about the big cars but the GTO had a problem with the power take off from
power lead coming right off the back of the alternator. Ours used to blow or fry the inline fuse all the time. This wire powers the AC clutch and blower motor. A service
bulletin called for 2 thirty amp fuses in tandem. I stepped up and put a huge 1/2 bladed spade fuse in there and solved that problem after 50 years. Another consideration
is a vacuum leak if lines have been messed with. Also, the vacuum motors that control the door flaps are on their last leg after all these years. I had to replace 2 of mine.
In the driveway, watch the compressor cycling on and off and satisfy yourself that it is not about to seize up based on engine RPM changes. Could also be over filled with
oil or freon.

[lust4speed]

Originally Posted by Jerry H.

...bypassing the original push button switch...

Wonder what circuit they tied into for the A/C after changing the wiring. Old fuse contacts usually have some corrosion and a new and larger load might be dropping out right at the fuse.

[carbking]

If the air conditioning system checks out OK, AND the hesitation is not too objectionable; I would drive it until the tank is almost empty, then fill with fresh fuel.

I read your comment about Stabil. Last summer I bought an expensive DR trimmer. I am pretty good at following instructions, and DR said warrenty voided unless Stabil used in the fuel. So when I put my various small engines to bed last fall, mixed Stabil according to directions for each, ran each long enough to get the mixture in the carburetors, and left it for the winter. This spring, every single one of them have a stopped up carburetor! At least DR is honoring the warranty. I tested all of the fuel stabilizers available locally, and found no benefits, and until last winter, have not used them. I'll guarantee last winter will be the last I use it!

Those small engine carburetors are worse than rebuilding than any passenger carburetor I am aware of, made in the last 80 years.

Jon.

[mgarblik]

As the Carb King you have tons of experience. How do you recommend storing collector car fuel systems and small engines for the winter? I have used Stabil, and stored with the tanks full and empty. Never really settled on a method that was much better than the other. Storing with the tanks empty at least meant in the spring when fresh fuel was put in the engine ran correctly right away. Thanks in advance for the tips.

[Jerry H.]

I only drove it once after I bought it before the AC was worked on. The AC wasn't working then but I don't remember any hesitation.

The reason the switch was bypassed it because it was bypassed when I got it and the wiring was a mess! The guy who worked on it put it all new wiring with a larger gauge than before. He used a heavy duty switch and put in extra fuses.

I'll check to see if it is cycling when it gets warm enough to run it. Expecting frost tonight.

I didn't run any fuel stabilizer until the GTO with the 2x4's (with Jon's kit) wouldn't hardly run after sitting over the winter. I've run it ever since with no problems after thewinter.