Car stalls on hard braking

Posted By: RapidRunner

Car stalls on hard braking - 10/03/06 04:39 AM

I was executing a hard braking exercise in traffic the other day

not by my choice.

During the braking as I pressed harder on the pedal to quickly stop the car the engine idle continued to drop until it finally stalled out. No problem restarting it though.

I checked the float level on teh center carb when I got home and it was right at the bottom of the sight hole just slightly dribbling out.

Any suggestions?

MikeE

Posted By: Quicksilver440

Re: Car stalls on hard braking - 10/03/06 05:25 AM

I had a similar problem...here's my post...maybe it will help you. I havn't had mine out yet again to test mine....

https://board.moparts.org/ubbthreads/show...&PHPSESSID=

Posted By: RapidRunner

Re: Car stalls on hard braking - 10/03/06 06:33 PM

rvoyles,

Thanks for the reply.

First let me say that your cars looks awesome.

I love the look of the silver and black

I do not think I have a flooding problem. If I start to brake hard the idle will start to drop smoothly(almost linearly) below 900 like you are turning the idle screw down. If you let off the brake the idle comes back up. If you press harder on the pedal the idle continues to slowly, smoothly drop to 0 and the cars stalls.

Once it stalls you can start it right back up like normal, just turn the key, no need to playing with the throttle.

I'm not saying it can't be a flooding problem just one I am not fimilar with. I would have expected a hard start if it flooded.

Manual steering and manual brakes if that helps??

MikeE

Posted By: scatpacktom

Re: Car stalls on hard braking - 10/03/06 07:35 PM

I agree,float levels

Posted By: A12

Re: Car stalls on hard braking - 10/03/06 07:47 PM

Does it do that in reverse too?

MikeR

Posted By: A12

Re: Car stalls on hard braking - 10/03/06 07:54 PM

Float valve.

Float pivot.

Float with pin hole.

Float vent.

Take that carb and get your money back from the

you got it from

MikeR

Posted By: Troy

Re: Car stalls on hard braking - 10/03/06 07:56 PM

Quote:

Does it do that in reverse too?

MikeR

Remember your brakes only work about a third as well going in reverse as they do going forward so WATCH OUT!!

Posted By: 6365Abody

Re: Car stalls on hard braking - 10/03/06 07:56 PM

I had a thought. My first thought was carb floats, and it still may be something wrong with them. But after you said braking, esp when you brake hard, I think you may have a vacuum leak in your braking system, that is, if you have power brakes. I think it maybe a problem with both the brakes and the floats. Try different things with the brakes, such as breaking with the vacuum line pinched off and see if the engine still dies.

Posted By: XXHEMI

Re: Car stalls on hard braking - 10/03/06 11:25 PM

Rapid

Try adjusting the air mixture screws on the out board carbs. I know it don't sound right but I had the same problem with a new set of Holley's right out of the box. Tried everything until that fixed it.

Posted By: Quicksilver440

Re: Car stalls on hard braking - 10/03/06 11:41 PM

Quote:

rvoyles,

Thanks for the reply.

First let me say that your cars looks awesome. I love the look of the silver and black

I do not think I have a flooding problem. If I start to brake hard the idle will start to drop smoothly(almost linearly) below 900 like you are turning the idle screw down. If you let off the brake the idle comes back up. If you press harder on the pedal the idle continues to slowly, smoothly drop to 0 and the cars stalls.

Once it stalls you can start it right back up like normal, just turn the key, no need to playing with the throttle.

I'm not saying it can't be a flooding problem just one I am not fimilar with. I would have expected a hard start if it flooded.

Manual steering and manual brakes if that helps??

MikeE

Thanks for the kind words...

I agree that the engine restarting so easily doesn't really sound like a flooding issue. Mine was always hard to restart....but only occured under real hard breaking.

Just a though...whats your idle sitting at in gear? Could you have it so low that any flutter in the carb is causing a stall? Maybe try raising the in gear idle a touch....just and idea.

Posted By: A12

Re: Car stalls on hard braking - 10/04/06 01:24 AM

Okay MikeE, here's a reach....a bad idle solenoid, brake lights come on and solenoid steps back a little...............come on I'm really reaching here

turn the idle up way higher than normal, I would think if it's a carb float issue it would still stall with a very high idle

Does it stall with the trans in neutral and you get on the brakes hard?

Posted By: RapidRunner

Re: Car stalls on hard braking - 10/04/06 04:04 AM

Quote:

Float valve.

Float pivot.

Float with pin hole.

Float vent.

Take that carb and get your money back from the you got it from

MikeR

I thought about logging a complaint, but the bowl and float are mine from my center carb. remember

The float checked out okay when I had the carb apart so i do not think there is a hole in it.

Funny thing is mikeR I was talking to my dad tonight and he mentioned the idle solenoid also. My only thought on that is that it would do it all the time when you pressed the brake, unles the short only happens when the front end is dipping down.

Yes I tried the hard braking after putting the car in neutral and it does the same thing.

I cannot say I tested when the car was cold becuase I just noticed this weekend when I did the hard stop on teh highway. After it did it once I did some testing on the way home like braking hard in neutral, start braking hard and then letting off the brake. Brake slow and then about 5mph hour stop hard (this time the RPM dropped but recovered)

MikeE

Posted By: RapidRunner

Re: Car stalls on hard braking - 10/04/06 04:09 AM

Quote:

Does it do that in reverse too?

MikeR

Never tried. Might try this weekend if the weather is nice.

MikeE

Posted By: RapidRunner

Re: Car stalls on hard braking - 10/04/06 04:10 AM

Quote:

I had a thought. My first thought was carb floats, and it still may be something wrong with them. But after you said braking, esp when you brake hard, I think you may have a vacuum leak in your braking system, that is, if you have power brakes. I think it maybe a problem with both the brakes and the floats. Try different things with the brakes, such as breaking with the vacuum line pinched off and see if the engine still dies.

Manual Brakes, Manual steering and a 4-speed.

Only vacuum connection is a vacumm guage.

MikeE

Posted By: RapidRunner

Re: Car stalls on hard braking - 10/04/06 04:16 AM

Quote:

Rapid

Try adjusting the air mixture screws on the out board carbs. I know it don't sound right but I had the same problem with a new set of Holley's right out of the box. Tried everything until that fixed it.

XXHEMI,

Interesting. Never would have thought that. THey do need adjusted, I know this because they effect teh idle too much. (menaing if I cover teh airbleeds on teh outer carbs the idle drops on teh motor)

This unfortunately will be a longer time off before I get the time to mess with the carbs completely.

MikeE

Posted By: Alaskan_TA

Re: Car stalls on hard braking - 10/04/06 04:35 AM

I had a similar problem a couple yars ago. It ended up being the thrust bearing, it failed and on hard stops the crank shaft was actually sliding forward in the mains. When the middle counterweight contacted the main web of the engine block the engine would stall. It always restarted except for the last time....

When I tore it apart I found out that the crank shaft had eaten away about 1/4" of the material in the main web. I had to toss the engine it was so far gone.

For your sake I hope it is a fuel issue.

Barry

Posted By: RapidRunner

Re: Car stalls on hard braking - 10/04/06 04:58 AM

Man, Don't scare me like this.

Is there any way to check for that short of dropping the oil pan?

The motor is all new and clearences checked on assembly. I know that won't stop a defective bearing prblems but it should help revent a good one turnign bad...

MikeE

Posted By: 62maxwgn

Re: Car stalls on hard braking - 10/04/06 12:23 PM

Mike,you know that your engine is a big vacuum pump.Disconnect the vacuum advance on your distributor and see what happens.

Posted By: captaindodge

Re: Car stalls on hard braking - 10/04/06 04:35 PM

I have same problem with my AVS 4bbl on 440 Charger, but it will also stall on hard left turns but hard right turns are no problem. (this is with foot off gas pedal). Setting float level low seems to help but no solve the problem.

Posted By: 62maxwgn

Re: Car stalls on hard braking - 10/04/06 05:41 PM

Quote:

I have same problem with my AVS 4bbl on 440 Charger, but it will also stall on hard left turns but hard right turns are no problem. (this is with foot off gas pedal). Setting float level low seems to help but no solve the problem.

There is a fix for that in the old Tech Bullitens.If I can find it I'll post it.

Posted By: RapidRunner

Re: Car stalls on hard braking - 10/05/06 04:07 AM

Quote:

Mike,you know that your engine is a big vacuum pump.Disconnect the vacuum advance on your distributor and see what happens.

Currently running an accel dual point with no vac adv.

Vac adv port plugged on carb.

I am idling at 950-1000 with 15-16" vac at idle so I do not think I have a intake leak

MikE

Posted By: captaindodge

Re: Car stalls on hard braking - 10/05/06 11:25 PM

Do you remember the fix having to do with adding a second fuel supply line on the driver side of the AVS

Posted By: 62maxwgn

Re: Car stalls on hard braking - 10/05/06 11:53 PM

Quote:

Do you remember the fix having to do with adding a second fuel supply line on the driver side of the AVS

No second fuel supply.If I remember it had something to do with the booster nozzle modification.May take a while but I'll find it..

Posted By: RapidRunner

Re: Car stalls on hard braking - 10/17/06 08:58 PM

Quote:

Does it do that in reverse too?

MikeR

It stalled on me this weekend again when coming back from a show. Discovered 2 things.

1. Does not do it in reverse (I love the whine when you are doing 20MPH in reverse

)

2. When it stalled on me I decided to do a little test. I started the car and went for a little drive and did the hard stop, car stalled and I got out and took out the site plug in center carb. Fuel level was below the site plug a bit. I had to shake the car a good bit to make it splash out. However when I started the car the level came right back up just below/trickling out.

Could it be a bad float or needle seat some how?

I really hate to tear the center carb off again. I might try changing the needle/seat this weekend??

MikeE

Posted By: A12

Re: Car stalls on hard braking - 10/17/06 10:11 PM

MikeE, to me it just sounds like the float level is set just a little too high. The fuel difference between the low or lower than the site hole and the restart level is what is surging into the engine and stalling it. IMO.

If you did deliberately set the float level to the "just trickling out the site hole" and that�s where it is when you start the engine then I would think the floats are okay. We�ve had floats that have developed a leak (hollow floats) and they become less buoyant and during hard deceleration or a bump coming into a corner will open the float valve and let it a surge of fuel that stalls the engine. Do the floats have the weight on them so you can weigh them to see if they are okay?

If the floats are bad or the float valve is bad then they would not shut the fuel off and when you started the engine and the fuel pressure increased the fact that it didn�t come gushing out the site hole tell me they are okay. I still think the symptoms indicate too high of a float level setting. Does hard forward braking surge the fuel toward the venturies or a path toward the intake manifold? Is there a baffle system to stop this surge or does it rely on the float level setting? Just throwing things out there...

MikeR

Posted By: 62maxwgn

Re: Car stalls on hard braking - 10/18/06 12:45 AM

MikeE,you may want to try lowering the float level in the center carb.You may not have noticed but the sight plug sits approximatly 1/4" higher on the center bowl.If you adjust so fuel just trickles with sight plug removed as recommended,the center carb will have a higher fuel level that the ends.

Posted By: captaindodge

Re: Car stalls on hard braking - 04/27/07 02:47 AM

Quote:
--------------------------------------------------------------------------------

Do you remember the fix having to do with adding a second fuel supply line on the driver side of the AVS

--------------------------------------------------------------------------------

No second fuel supply.If I remember it had something to do with the booster nozzle modification.May take a while but I'll find it..

Posted By: Scatransit

Re: Car stalls on hard braking - 04/28/07 01:37 AM

Hey Mike, Just a thought...Reach cruising speed and shift to neutral. While coasting, raise the RPM with the gas pedal to say around 2500-3000. Stop in the same manner that duplicates the stalling event, and see if it stalls. If it doesn't, then it is possible that the fuel pump is not providing enough volume at lower RPM levels. Another thing I remember (back in the day) is having a car that stalled when coming to a stop. It had a bad fuel line (hose) before the pump...It actually sucked air rather than leak fuel! The nature of the hole (a crack actually) acted like a valve allowing air in but no fuel out. At lower RPMs the pump suction could not over come the leak in the hose and the carb was starved...It kicked my butt for about a week before I pinned it down...Strange but true! Good luck!

P.S. I'm sure the latter doesn't apply to you, just thought of it while I was typing!

Posted By: captaindodge

Re: Car stalls on hard braking - 05/04/07 04:41 PM

I lowered the float level in my AVS to 7/16 which is the Edelbrock spec,(FSM spec is 7/32) and no more stalling under hard braking or fast level left turns but I get some hesitation on fast uphill lefts. Should I raise the driver side or pass side float a little? Now I understand why Holly has externally adj floats.

Posted By: captaindodge

Re: Car stalls on hard braking - 11/22/08 10:13 PM

Quote:
I have same problem with my AVS 4bbl on 440 Charger, but it will also stall on hard left turns but hard right turns are no problem. (this is with foot off gas pedal). Setting float level low seems to help but no solve the problem.

There is a fix for that in the old Tech Bullitens.If I can find it I'll post it.

62maxwgn did you ever find that Tech Bulliten?