Hi Guys,

I need some opinions on a stalling issue I am having on a 66 Coupe with a 200 I6 Automatic.

The car starts okay, I say okay because sometimes you have to pump the pedal more times than others. The carb has been rebuilt and the accelerator pump has been changed and does work.

Once it starts the car will run fine for about 10-20 minutes and then when you slow down and the motor comes down to an idle speed the motor will stumble and stall. If I keep my foot on the gas it will run but wants to stall. For the first 10 or 20 minute the motor runs great and even runs good as long as you keep your foot on the gas pedal or at highway speeds. Sometime it does feel like there is a slight miss in the motor. I checked the plugs and they all look good.

I checked the RPM in park and it is set at 800. The timing is right, the plugs, wires, point and distributor cap are all new.

I am at the point where I am just going to start guessing so I figure I would check with the pros before I start randomly replacing parts.

If you have any suggestions what I should check next please let me know?

Thank You,
Jay

 

maybe the first 10k you drive with choke on-> no problems. then it warms up, choke switches off, car stalls as idle is too low.

let your car warm up without driving in park. When warm give her a quick tap and that should flick off the idle. what's the idle set to now?
block the car so it can't drive anywhere (against a wall with a wheel inbetween or similar, put into gear and adjust idle to 700 and make sure to re-adjust the idle mixture screw.
idle mixture screw turn in until the rpms drop, then slowly turn out by a quarter turn each time until the engine rpm doesn't increase anymore

 

It is not a choke issue, I have verified that the choke is fully open after just a couple minutes of running and at that point the motor runs fine.

I checked the idle when the fast idle was fully disengaged and it was at 800 in park. After the motor starts to stall it will stall even in park. I will check the rpm in gear once the car is running but I still think it will stall since it will stall in park also.

Is it possible that it would not be getting fuel once it gets warms? Can a fuel pump fail only when it gets hot?

 

yes, it's a very probable cause. not neccesarily the fuel pump getting hot, but maybe the carb get's too hot causing vapor locking.
You can try a spacer between intake and carb. If you have a fuel pressure gauge (they're cheap) hook that up inline between pump and carb.
If you see the pressure dropping and this causing too stall the engine then at least you know what yoiur problem is. I had the same issue back a good while and needed to change fan, pulley and add a spacer to get rid of the problem

here's how that looked like:
http://www.youtube.com/watch?v=TYVjUuL2myg

Kalli

Kalli

 

Well I took your advice Kalli and checked the RPM in Gear. I had someone put there foot on the brake while it was in drive. The rpm was around 600 so I turned it up to 700 RPM so it now runs around 900 RPM in park.

I took it for a drive and it seems to be working better now, I will drive it a bit farther later on today.

I just can't see how that would be the only problem since when it would start to stall and I would shift into neutral it would still want to stall so the RPM's should have been fine in Neutral.

We will see.

Thanks
Jay

 

It could be fuel boiling out of the lines as Kali said. That or maybe a vacuum leak that only rears it's head when the engine is hot.

 

I took it for another couple rides and the problem seems to be gone since I turned the idle up a little. I hope thats all it was but I am doubtful since it would also stall in park after it initially stalled in gear.

Time will tell, if it comes back I will check the other things out and let you guys know.

For now I can't complain though.

Thanks Again

 

Well, as I suspected the problem returned, but only worse and it does it even when cold now.

I started the car which did start fine but sounded a bit rough so I thought I would take it for a spin around the block.

When ever I gave it gas it felt like it was missing on a few cylinders. When I let off the gas it sounded a bit better. I repeated the procedure a few times and it kept doing the same thing.

Finally after 2 laps around the block it stalled on me when I let off the gas going around a corner. I started it back up and took it home.

Any ideas?

 

Sounds like the idle fuel adjustment is "off", or clogged. Usually an easy fix. Worst case is you have to rebuild the carb, and these are easy.

 

The trouble sounds like you have not adjusted or did not include to mount the "dash pot" or anti stall solenoid. The component is found on the side of the carb linkage. It's sole purpose is to prevent a car that has an automatic transmission from stalling as it reduces speed and comes to a stop. The solenoid or dash pot (earlier years like yours), activates a tiny plunger that prevents the carb from closing off. It artifically keeps the curb idle up as the car is in drive. You're driving at speed and you approach a stop sign. The car slows down as you apply the brake. The solenoid/dashpot activates to keep the throttle linkage "open" a tad more then curb idle. This is common after carb rebuilds. If you have a Haynes manual the procedure for setting up the dash pot is included in the carb adjustment section. It's a simple procedure.