69 351 Stalling, need help

[nickd74]

Hey,

I'm having a stalling issue with my 69 Mustang, it has a 351 4V Windsor, Auto 3spd.

Car used to only stall after full throttle jabs. Now it will stall periodically just during operation. Stall will happen when moving or when stopped, just feels like a loss of power.

Car will start up again after a round of cranking and pinning the pedal. I believe it is flooded, as I don't pump the pedal, but just pin it once and keep cranking.

So far, I have:

Changed the coil
New plug wires
New plugs
New cap
New rotor
New fuel filter (but WOT is better than ever, so....?)
Took the top off the carb, everything inside is clean as clean.
Air filter is in good shape
I believe the breather on the driver's side valve cover is flowing properly....is there anyway to confirm that?

I could sure use some ideas, really stumped.

Thank you,
Nick

 

[WORTH]

Hey,

I'm having a stalling issue with my 69 Mustang, it has a 351 4V Windsor, Auto 3spd.

Car used to only stall after full throttle jabs. Now it will stall periodically just during operation. Stall will happen when moving or when stopped, just feels like a loss of power.

Car will start up again after a round of cranking and pinning the pedal. I believe it is flooded, as I don't pump the pedal, but just pin it once and keep cranking.

So far, I have:

Changed the coil
New plug wires
New plugs
New cap
New rotor
New fuel filter (but WOT is better than ever, so....?)
Took the top off the carb, everything inside is clean as clean.
Air filter is in good shape
I believe the breather on the driver's side valve cover is flowing properly....is there anyway to confirm that?

I could sure use some ideas, really stumped.

Thank you,
Nick

is it running smooth before it stalls?
any black smoke?
how does it start cold?
manual or auto choke? and is it opening all the way?

 

[nickd74]

Runs smooth, and the stalling when running does not seem to exhibit a pattern.....ie. car is cold, sometimes does it..........car is warm, sometimes does it.
Just before it stalls though, it will start to labor, at stops you can notice it, at speed, it just seems to be losing power and then it dies.

It will always stall after a WOT throttle blast though.


Starts no problem from cold. Starts no problem when warm. Only time it takes a moment to crank is after it stalls.

Doesn't burn oil or smoke at all. However, after a stall the startup will cause a puff of black.............that's why I think it's flooding somehow.

Choke is auto and I haven't noticed a difference in the way it performs. It'll kick the revs up when cold and kick down when warm.

Thoughts?

Nick

 

[streetgrande69]

Runs smooth, and the stalling when running does not seem to exhibit a pattern.....ie. car is cold, sometimes does it..........car is warm, sometimes does it.
Just before it stalls though, it will start to labor, at stops you can notice it, at speed, it just seems to be losing power and then it dies.

It will always stall after a WOT throttle blast though.


Starts no problem from cold. Starts no problem when warm. Only time it takes a moment to crank is after it stalls.

Doesn't burn oil or smoke at all. However, after a stall the startup will cause a puff of black.............that's why I think it's flooding somehow.

Choke is auto and I haven't noticed a difference in the way it performs. It'll kick the revs up when cold and kick down when warm.

Thoughts?

Nick

sounds like a sticky float to me. what carb?

 

[nickd74]

The floats moved very freely when I had it apart.

It's an Autolite 4300 4V.

Is there any way to check and see if they are hitting the inside of the bowl walls and sticking?

Thanks,
Nick

 

[bnickel]

maybe a couple of dumb questions but are you still running points? if so it could be the that the condensor is intermittently not operating also where do you have the coil mounted? if you still have the points change them and the condensor also check the primary wire from the distributor to the coil. i used to have that problem occasionally, i also had problems with the coil when it was mounted on the driver side of the intake the hot wire would somehow get caught in throttle linkage just enough to pull it loose from the coil but not pull lt completely off, i also had one go bad from sitting on it's side in that position and overheating the windings. i moved the coil the front of the passenger side head, which is also a correct mounting location, and have never either of those problems since then. just some things to check in case it is not actually carb related

 

[nickd74]

The coil is located on the front of the passenger side head.

As for the points, yes, still running them, I do not think there is a condenser though.

I do have the Pertronix retrofit, but had hesistated putting it in to remove the points as I had assumed they were working properly.

Along these lines, I have also tested the vacuum advance on the distributor and it applies and releases correctly.

I do not think it is a wire, as it will start back up 100% of the time and a wire would most likely be less consistent in the way it comes back around.

Thanks,
Nick

 

[bnickel]

mine would start back up most of the time until it happened so many times then just quit until i finally figured it out. i'd go ahead and install the pertronix jsut to eliminate that apsrt of the equation. if it still happens after that i would look into the carb more then, but as it stands i don't think it is 100% carb related although the carb may factor heavily into the equation. you might also think about checking out the fuel pump as well, i have heard of pumps going bad and actually end up supplying too much fuel to the carb but i can't say i've ever seen it personally though

 

[Max Power]

It is an intermittent problem, and a lot of the fixes you have applied wouldn't usually be intermittent.

If you have points, you should have a condenser. I have seen them be erratic on an intermittent basis, so I would put that Pertronix in post haste. They work great.

If you still have a problem, then I would chase into the fuel system. When it stalls, go under the hood and dig into that carb and see what is happening. You coulkd be either running out of fuel or flooding.

Sinse flooding rarely is bad enough to cause a car to stall, I would guess you are sarving it somehow, but it is hard to tell.

First thing I would do is install that Pertronix and then carry carb tools around with you as you drive around.

 

[Ozsum2]

I'm with Max. Sounds like it is running out of fuel. Check the fuel filter even though it is new. Sounds like it starves out, then after a spell of sitting and cranking, you get enough fuel through to restart.

 

[69Rcode_Mach1]

Could be a leaner also.I had the same problem it was just lean. try richening idle or richening jets if that doesn't work.

 

[nickd74]

Guys, thanks for all the help.

I had a bit of an enlightenment today and it's leaning towards what you said above.

Whenever you drive downhill against the gears (like in 2nd or something) no gas applied, the engine will die. I had forgotten about that mode of failure.
(*Hey, I only see the car two weeks a year!)

So why is that?
My guess....fuel pump is either oversupplying fuel at the higher rpm with no opening of the throttle, or the engine is just starving.

I'm gonna put in the pertronix and then look at the fuel pump.
I only have until next Friday to sort this all out and I have the rad out right now as it was leaking.


PS> Do not start your car with the tranny lines disconnected from the rad.......10+ litres in seconds.......oooh the driveway is not happy.

Thanks again for all your help,
Nick

I'll keep you posted.

 

[nickd74]

Update:

Plug wires are in.
Pertronix is in.
New Rad is in and no more drips

Stalling still happens.

I'm noticing more and more it happens only at idle, after idling for a while. It'll rev up quite happily, but can't seem to stay idling once the problem happens.

I also for the first time noticed a hesitation at WOT.

Sooooooooooo.....

My next move is to change the fuel pump and if that doesn't solve I may have to remove the carb and tank it.
I also supposed that an unrestored engine that is 40 years old might just be showing it's age, but then why only at idle?

I'm really leaning towards the fuel pump now.............but car is going back into storage today, so it'll have to wait until next year

Anyone have any recommendations on a fuel pump or just what I can get at the parts counter?

Thanks,
Nick

 

[bnickel]

well, now you're changing things. if it only does it at idle it may be something as simple as adjusting the idle mixture screws and/or the idle speed adjustment screw. also make sure the choke is fully opened when it starts acting up, i have seen bad choke thermostats that tend to "back-off" a little once the car is warmed up and has been running for a while. if all that checks out then i would think about fuel pump/ carb rebuild

 

[nickd74]

Yup, checked the choke, it takes a while like you said, kicks down the rpm a couple of times, but it eventually kicks all the way off. So I know it was off, and I can hear the rpm difference and I know it has not some how come back on when the car quits.

As for the idle setting, I think that's ok too. The car will be sitting idling perfectly, low rpm rumble for up to 3 minutes or so, then lump lump lump dead. I believe if it was the idle screws, the idle wouldn't work right at all.

I'm pretty certain it's the pump now.

Anyone have a good source? or parts counter? Please advise.

Thanks for all the input,

Nick