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hi all,    let me lay a problem I'm having,    the car drove fine a week ago,  today I went for a ride an at every red lite while in drive it felt like it was going to stall,  had a chugging effect,   it idles fine,.    geez,  I forgot this is the 57 forum,    I'm talking about my mustang 69 mach 1 that I'm having the problem with

How old is the gas? First question that comes to mind. Might be time to take it out on the highway for a 1/2 tank drive...or more.

  I had the same sort of issue in my 68 GT/CS. Checked all the fuel system, overhauled the carb and it still hesitated, sputtered. Turned out to be the ignition points. So don't count out weak or worn ignition parts.

to bot,  rm57 an mustang6984,   the gas is probly old,,  an right a trip down the hwy might help,  the distributer is petronic   

I'd run it until the tank is about 1/2 empty...maybe more...then fill it and come on home. Try the lights again and see if that improved.
IF that doesn't do it...might be the ignition. Buddy of mine has the same as you...and his was bad...causing him to have issues once it warmed up. New unit...runs like a Swiss watch, Technology...its great...until it isn't.

to mustang6984,         whats the lites have to do with it?,    an your friends new unit,  what would that be?,  thanks for the help,   jerry

Quote from: geraldchainsaw on 2026-08-28 21:11to mustang6984,         whats the lites have to do with it?,    an your friends new unit,  what would that be?,  thanks for the help,   jerry

Sorry...shorthand speak doesn't work well in forum speak! LOL!!!
I meant to try driving through the lights again...see if it does okay after that freeway road trip...if it eliminates the issues you currently have at stoplights.
I am not sure what he bought. I will ring his chimes tomorrow and ask what e had and what he has now. Let you know tomorrow.  :003: (His ride is a '64 T-Bird with the FE engine and C-6)

Hello  If weather is hot, probably vapor lock. Pat F in Texas has good advice on vapor lock, if thats the problem.

I've had the mustang for 30 yrs,  never had a problem with vapor lock.    I've gotten old,  maybe its time to sell

Quote from: geraldchainsaw on 2026-08-29 10:16I've had the mustang for 30 yrs,  never had a problem with vapor lock.    I've gotten old,  maybe its time to sell

Nope...not time to sell.
So...apparently after several electronic ignition systems he did what I had suggested...went back to points/rotor/condenser and has had no issues since.
I know there is testing equipment out there to check those modules but I do not know if there is a home mechanic version.
My knowledge on those things is very limited other than they are great...until they are not. A shop could probably check out the module, or maybe Gary would know something about them. But what you are experiencing sounds a lot like what my buddy was dealing with. I'd try the freeway cruise, and if that doesn't fix it...then shop time perhaps.
Sorry not more help.

Try a different condensor. 

to abe lugo,   I'll give it a ck,  thanks                 ok,   what condenser?,   I don't have [points,  I put a Petronic system in

ok,  to KULTULZ,    ITS JUST THE ADD ON SYSTEM,  MODULE IN A FORD  DIST

Is it the original 1957 FYB DIST?

You did a conversion? IGN I or IGN II? Used what coil?

Remember, the module only gives a hotter spark, mechanical and vacuum advance are still mechanical.


CARB type? Fuel pressure good?

Wait a minute ... I can't seem to be able to read ...

It is a 1969 MUST?

Different story,

What engine and trans?

It runs fine until you let off the fuel at a stop? Does it still have the IMCO two signal advance on the DIST ADV? Have you removed all the EMISSION FEATURES?

ok to KULTULZ,    its orig ford dist,  been years since I installed the Pertronix,  all I can say is it was off shelf,  so i don't know if it was 1 or 2,   carb type 650 double pumper,  never cked the presure   I'm sure the problem is a simple one,  I'm just not good enough to find it.   like I said,  it idels fine,  going  down HWY no ;problem  only when I come up on a red lite. acts like it wants to stall

Quote... idels fine,  going  down HWY no ;problem  only when I come up on a red lite. acts like it wants to stall

So the only time it does this sis while letting off the fuel for a stop?

Is it AT or ST?

You need to check DIST ADV and fuel pressure. The CARB is adjusted correctly?

asfaik these years started with quite complex emission control systems. check all the vaccuum lines and hoses !
if it's AT, also check the vaccuum unit on the trans.

first,  thanks for all info given.   I think its time to take it back in to the shop.    off hand I don't know what AT or ST is,      the vacumn lines would seem to be alright since idle is ok,   an since I have no rack to look underneth it'll have to go in to ck trans.   is AT automatic trans?,  ST stick?   thanks again     jerry                                        I might add its a FMX trans,   the idea of vacumn unit on trans is a good possiblity,  its  raining here today,  so I'll ck the auto manuals.   I might add,  being 88 I can't do the things I use to,  all I can do is ask questions or have someone do my work.     jerry

ok,  it was brought up it could be the vacumn mod on the trANS, ANY ONE KNOW WHAT IT DOES?    JERRY

Quote from: geraldchainsaw on 2026-08-30 10:41ok,  it was brought up it could be the vacumn mod on the trANS, ANY ONE KNOW WHAT IT DOES?    JERRY

That will be the modulator valve. It controls shifting.

It or the vacuum supply line can go bad.

AT = AUTO
ST = STD

If yours is an AT, is there a dash-pot on the carb linkage?

What engine and is FMX?

no dash pod on carb,   351w   with FMX trans,  was hopeing it was the vacumn mod on trans,  now not sure

The purpose of a dash pot (or vacuum/electric solenoid/throttle kicker) is to lessen the drag on the engine from the torque convertor while coming to a stop.

HOLLEY does offer one.

It is difficult to diagnose a problem over he net without specific build info/photos.

into the shop it goes, thanks for all of the help,   jerry

Let's us know what they find ...

ok,  update.    let me tell the whole story before you say anything.   I had to help the mech,  press on brake put in drive,  he sprayed all around eng,  1 spot the eng smooth out,  turns out the front of eng intake manafold has a leak, the cork gasket an silicone leaks. ,   now the correct fix is to take the manifold off an redue it,  but,  since its going to cost  a arm an ;leg,  we come up with a cheaper way of doing it,  may work an may not,  if not then the hard way.   hes going to take the dist off,  clean up around gasket area, silicone the area, , might do it an then maybe not,  we'll have to see.    an thats whats happening.   any thoughts?    jerry

Short term...might work. But long term...gonna need to pull it and do it correctly. Shouldn't be all that expensive to just R&R the intake and new gasket for it. Less than a day's work...maybe 4 hours worth.
Good luck.

I'm 88,  how old are you?     didn't m,ean to sound sarcastic,   ,   I just have a harder time doing things any more

I thought you went back to points.  Nevermind. 

Quote from: geraldchainsaw on 2026-09-01 16:39I'm 88,  how old are you?     didn't m,ean to sound sarcastic,   ,   I just have a harder time doing things any more

Understand...I am just a youngster compared to you...only 73. LOL!!! If we were closer I'd pop over and do it with you. But I am in Branson MO area.  :003:

Quote from: geraldchainsaw on 2026-09-01 16:39I'm 88,  how old are you?     didn't m,ean to sound sarcastic,   ,   I just have a harder time doing things any more

You are tougher than I am, 78 with blown knees and stenosis.

I need a new handle. Cannot decide between THE FALL GUY or CRAZY LEGS.

thanks for the thought mustang 6984

Jerry, don't beat yourself up over the fact you can't do everything your self any more. At least you can still drive. I'm headed for 80 and because of my loss of site haven't been able to drive my cars for the last 6 years. I see just good enougf to get around,I have to say it took some time getting used to riding shotgun but at least I can still get out and go. I think that most of us that are on this site are at the age we all have issues and have to learn to adjust. So I think at 88 you have payed your dues, and if it cost a few more bucks to keep them running,do it and enjoy the ride, you've earned it. Take care, Alvin

Quote from: geraldchainsaw on 2026-09-02 08:23thanks for the thought mustang 6984

 :006:  :003:

ok,  cars been in repair shop for a week,  still no word,   like I said we're trying for a easy fix,  but in case it don't work I ordered a intake gasket set from NPD, it came the otheer day, , ,  it ,has the main gaskets 2 cork gaskets,,  an a what looks like a O ring about 1 1/2 in dia,  ,any one know what it is?

Should be the DIST O-RING.

Maybe consider RTV on the valley ends rather than cork seals.

ok,  update.     silicone didn't stop vacumn leak,   intake has to come off.    waiting to see how much this is going to cost,   now tjhe wife gets involved because of cost,  any one want to buy a 69 mach 1 with a vacummn leak?

I just pulled the intake off my ElCamino two weeks ago.   The gasket at the front china wall was seeping over the edge.    Took longer than I thought.  I was not in any hurry, and it was not a difficult repair, but I still had about 6 hours in it.    Take an intake off ya gotta drain the water.

Quote from: geraldchainsaw on 2026-09-11 08:57ok,  update.    silicone didn't stop vacumn leak,  intake has to come off.    waiting to see how much this is going to cost,  now tjhe wife gets involved because of cost,  any one want to buy a 69 mach 1 with a vacummn leak?

    Your  Mustang is a really nice looking car and the best year in my opinion. Don't think you'll have any trouble selling it.

mustangs been in shop for week an half,  no word yet.  so much going on right now ,  wifes problems mostly.   but time will take care of everything.   , ,PS, , ,any one older then me on here?,  being 88 don't know how much more time I'll be driving

I don't know how long any of us will be driving.  Michigan passed a bill to mandate drivers 75+ will have to renew their license in person at SOS office every four years with more tests and medical documentation.  Part of the safe driving campaign.  80+ drives will renew every year in person.  Total age discrimination and money grab.  If old drivers are such bad drivers, why does the insurance companies give senior driver discounts??  All drivers should be subjected to the same renewal requirements.  If that isn't enough, Michigan has one of the highest gas taxes.  But there is more, a program is being piloted to collect two cents per mile on top of all the other taxes...whether or not you drive in Michigan or another state.  Then there is a bill limiting the driving of old cars ONLY on Sunday!

Quote from: gasman826 on 2026-09-21 15:17I don't know how long any of us will be driving.  Michigan passed a bill to mandate drivers 75+ will have to renew their license in person at SOS office every four years with more tests and medical documentation.  Part of the safe driving campaign.  80+ drives will renew every year in person.  Total age discrimination and money grab.  If old drivers are such bad drivers, why does the insurance companies give senior driver discounts??  All drivers should be subjected to the same renewal requirements.  If that isn't enough, Michigan has one of the highest gas taxes.  But there is more, a program is being piloted to collect two cents per mile on top of all the other taxes...whether or not you drive in Michigan or another state.  Then there is a bill limiting the driving of old cars ONLY on Sunday!

Nanny state approach to "governing" the masses...

Gary,  how did you find out all this,  I hadn't heard any thing,  luckly I don't think I would have a problem, I might be 88, , , I think I would hold my own,  just not lift things like I use to,   still kinda  quick & minds still sharp

I'm 85 plus, still drive 85 mph, pulled and rebuilt the engine in GMC 4x4 last week alone, still recuperating, but I'm not worthless yet.

ok,  update.   vacumm leak fixed,  now theres another problem,   says theres something wrong with carb.  ok,  I have a 650 double pumper on now,  what would be a good replacement?  I'll mess around  with it a little before I go buy a new carb

Gerald.. for all around street performance.. can't go wrong with an Edelbrock... there are folks that love them and folks that hate them...They are indeed trouble free though......

Gerald;  99% of carburetor problems are fixable, no need to buy expensive new carb.  Ran my 69 year old Teapots to an end of season car show in Townsend Montana, yesterday, 440 cars,  They worked flawlessly on the 180 mi trip with one 6400ft pass.  80mph most all the way.  I know I shouldn't be doing that because its turning 3200 RPM in OD with the 4:10s, but I cant help myself.  38degrees in the morning, but came home with top down.  Terrible gas mileage!

the mustang sure has had problems this year,   besides the vapor leak,  carb problem which I think I fixed,  now I was pputting it away for the year  I blue a power steering hose,  theres only 2 fittings took me 2 hours to mount it,  what a pain

That's a beautiful Mustang!