I give- head scratcher

[Handegard 10]

This started 2 months ago or so, after the car had been parked for 3 months (under cover)

 

Possible symptom-

Car cranks along time before firing up (only when it's been sitting) I attributed this to a fuel pump, and replaced it with a new unit. No change. Not sure if this is related to the main problem.

 

Main problem-

Fire the car up right? Let it warm up, don't let it warm up, doesn't matter. Runs great, good power, idles, etc. But if I try and drive anywhere, I make it not far (last night ~1/2 mile, few weeks ago, ~3miles) and I'll be sitting at a stop and it just stumbles and wants to die. If I give it some gas, it'll keep going, but I gotta keep the RPMs up higher than I'd like. It will continue on like this (driving fine mostly) for awhile sometimes, if I shift into neutral and hold the gas a bit at stops. But sometimes it won't, and last night it just died.

 

It sat for maybe 3 hours tops, and I came back, cranked along time, fired it up, and headed home.

 

This feels very much like how it behaved when we first got it, and the carb shop told me the advance was stuck, so I replaced the distributor. I've since warrantied the cardone distributor 3 or 4 times (the advance stuck on 2, the advance plate was partially missing on one, etc)

 

 

Things it's had done-

It got new plugs/wires/rotor/cap only ~3k ago (~1 year) and a new cap again a few weeks ago, finally put some BWD points in, and they are adjusted right.

 

The carb was rebuilt by a very good local shop, and they then dialed it in and set the choke.

 

The motor is otherwise a-OK, good vacuum, good compression, everything.

 

Anything? Car has been sitting over 2 months due to this, and I'm out of ideas after I put a new coil on tonight...

[MikeStang 247]

Hummm....why dont you swap to a ford Electronic distributor say from an early 80s model and get a 6AL box, that would be a good upgrade if nothing else....everyone says the petronix kits are good also, but you cant miss with a good ol electronic distributor.

But it sounds like a fuel issue to me.. What kind of carb are you running?

Mike

[Handegard 10]

Hummm....why dont you swap to a ford Electronic distributor say from an early 80s model and get a 6AL box, that would be a good upgrade if nothing else....everyone says the petronix kits are good also, but you cant miss with a good ol electronic distributor.

But it sounds like a fuel issue to me.. What kind of carb are you running?

Mike

 

Want to keep it as factory as possible. It's a all-original car so far.

 

The carb is a bone-stock 2bbl, recently rebuilt and tuned by a local shop that has been doing fuel/air work for many many years.

 

I have questioned the cab also, because the suddenness of the change in behavior I thought could be the choke opening, but I don't think it opens that fast does it?

[buening 63]

Have you replaced the fuel filter recently? Sounds like it could be a semi-plugged fuel filter

[CarZombie 25]

Try some gas treatment. Years and I mean years ago, a friend of mine had multipe problems with a jet boat motor (car engine). He finally figured out it was water in the gas and put in some STP gas treatment. That fixed the problem enough that he could run that tank out. You could also pump some of the gas out into a bottle look for signs of water. Let the gast rest a while and the water should separate out.

 

You might want to ask the carb shop if ethonal (spelling?) in the gas could affect the carb.

[LindenBruce 27]

When the car starts to stumble at stop signs, do you notice if your exhaust is pouring out black smoke? Sounds like the lead plugs at the bottom of the carb might be leaking causing a rich burn condition. I have had problems with this in the past. I used Loctite lock weld to seal the plugs during a rebuild. Ethanol could be an issue as well as water in your fuel. If the car has been sitting a lot I would suspect water or other fuel contamination.

 

If you have replaced all of the ignition components and still have the same problem, I would focus my attention else where. And I'm assuming you have checked your vacuum lines at the motor and at the transmission modulator correct? Bruce

[10851CVC 10]

Check your vacuum lines, especially the pcv valve line and the valve itself.

[LoneWolf2U 136]

Possible symptom-

Car cranks along time before firing up (only when it's been sitting) I attributed this to a fuel pump, and replaced it with a new unit. No change. Not sure if this is related to the main problem.

 

It sat for maybe 3 hours tops, and I came back, cranked along time, fired it up, and headed home.

...

 

 

Both of these statements are pointing to carb related troubles.

I would look at an internal leaking of fuel into the intake.

 

It sat and took a long time to fire again, this is from flooded and empty fuel bowl condition.

Sadly the fuels these days can cause these older carbed engines to have problems from the additives they use.

 

Easy test is remove carb and its top cover, while sitting atop a rag on the workbench fill fuel bowl with clean fuel and let it sit.

If the rag gets wet you know what the problem is.

[djs69stang 10]

http://www.1969stang.com/mustang/forum/showthread.php?t=8095

 

I had a similar problem as noted in this thread. Everyone said carb and it turned out to be electrical, namely a much needed, cheaply priced, ballast resistor. The problem was too much current from the coil and it was frying the points.

Check out this thread as it had some helpful hints, but the last "window" of the thread explains what I did to solve it.

[10851CVC 10]

http://www.1969stang.com/mustang/forum/showthread.php?t=8095

 

I had a similar problem as noted in this thread. Everyone said carb and it turned out to be electrical, namely a much needed, cheaply priced, ballast resistor. The problem was too much current from the coil and it was frying the points.

Check out this thread as it had some helpful hints, but the last "window" of the thread explains what I did to solve it.

 

I have had this happen to me. Not only will it fry the point it will smoke the coil too.

[Fordrevhead 29]

Does sound like crap spark to me too. I always replace the ballast when doing points since they're like 1.95 or less.

[Cruzzar 22]

Another possibility, check to see that it has a vented gas cap. I bought an old truch and it had a nice chrome gas cap under the seat---so I removed the old, ugly, rusted one and put the shinny one on. It took me a new fuel pump and three stops on the side of the road to figure it would run for a while until it pulled enough of a vacuum that the pump could not pump. Solution, put the old, ugly rusted cap back on.

[red71stang 10]

does sound like muck in the carb to me. get the top off the float chamber and clean it out, brake cleaner is best