2005stangGT

hi all. Any thoughts on this problem? I just bought this car a few months ago. It is a triple black convertible, 289 4speed. It was running fine, and then within the last week or so, the idle became quite rough, it stalls occasionally, and sometimes surges during acceleration. I replaced the fuel filter this Saturday and added a gas treatment, but that didn't seem to cure the problem. Also, I removed the air cleaner just to see if the problem went away, and it didn't. And when it does stall, it is hard to start. Any ideas are appreciated. Thanks. Eric

Big D

Same thing happened with our 65....try and adjust the idle speed on the carb....u might have to increase it a bit...could also be some bad gas....

chemeng

Do you live in a cold climate? These old carbs typically have to be adjusted between winter and summer driving. Summer air is less dense (hotter), the carb will need more to idle properly.

Big D

yea our car hates the cold weather :P

Galaxie

that's my guess as well..

depending on the condition of the carb, maybe it would be a good idea to rebuild it. you can probably get a kit from any autoparts store. All the seals and ports are probably gummed up.

I rebuilt the motorcraft carb on my Galaxie by myself and it ran great after that.

Skorch52

I agree with previous posters - sounds like air/fuel mixture to me. I need to adjust the a/f on my Holley with every 15 degree (F) change in temperature. Not much, but when it's driven every weekend, it's noticeable to me.

2005stangGT

Thanks for all the info. I want to rebuild a carb about as much as I want a hole in my head. But seriously, if I have to do that, I might as well replace the 2 barrel with a 4 barrel -- perhaps a 600 CFM? (This will give me room for improvement when I eventually replace the heads with something that flows better.) Any particular (new) 4 barrel carbs that are reliable, and reasonably priced? Eric

Big D

Holley's are real good carbs

chemeng

Holleys are the best in my book, most track guys use them. That said if you don't like adjusting the carb for optimal performance then Edelbrock is a better choice. Just put an Edelbrock on a friend's '65 two weekends ago. He is not mechanically inclined. Not bad but I think my Holley packs a little more punch.
If you like free flowing heads the Ford aluminum GT-40's are great, I bought a pair on Ebay for $814 delivered. Thought for sure it was a ripoff but they were as advertised. Main thing is to open up the valves a bit, remove the exhaust restriction, and add hardnened seats if you keep your original heads. Any good machine shop will know what to do. Try to find a guy that specializes in small block Fords.

Hope this helps, MikeR

LMan

also, check for vac leaks.

65fsbkhipo

With limited info so far... If it was running fine, a problem developed afterward. Warm or cold climate won't make it run any different. Sounds to me, none of you really know what the problem is...not enough questions. You're close on the carb deal...but take a look at the gas and most importantly the fuel sending unit. Could be it's clogged and sporadically giving gas? It could also be a vac leak as mentioned...but like you guys, I'm just guessing. NOT!!!

Big D

Hopefully its just bad gas....if it still does it onur next fill up then something is wrong

2005stangGT

It's not the sender unit (at least I would seriously doubt it). The sender unit is only about 2 months old - I just replaced it shortly after I bought the car (gauge didn't work when I bought it). I plan to bring it to Valley Performance (they are in MM & FF) and are close to where I am to take a look at it. Eric

Livewire

Timing?

Big D

if his timing was off it would be back firing like crazy

65fsbkhipo

Just because it's a new sending unit, doesn't mean it didn't get clogged with the dirt and rust that may have accumulated in the bottom of the gas tank. You made no mention that the tank was new or free of debri.

2005stangGT

Thanks for the additional point. The tank is "new." (I mean it's certainly not 40 years old.) It is a Ford gas tank. My guess is it's a few years old. Would there be an easy way to check this (without removing the sender)? Like with a fuel pressure gauge or something? Eric

BornInAFord

I'm guessing it's timing related, and that it's possible you've slipped a tooth on your timing chain. This would retard it, but not enough to cause backfiring. Rotate the distributor a bit to see if idle improves or not. If you have slipped a tooth, I'm guessing you might need to pull the water pump/timing cover and replace the timing chain/sprockets. BEFORE you go through more work, though, have you checked the sparkplugs to see if they are old/fouled up? What about the spark plug wires? Have you replaced the points in the distributor?

You also have a "sock" filter in the gas tank where the sending unit is. It's possible this is clogged. It's also possible the fuel pump is leaking into your engine... Pull the dipstick and smell the oil. If it smells like gasoline, something is wrong... To check for fuel pump function, remove the hose from the inlet of the fuel filter and place end into a jar or small gas can (jar is smaller and easier to handle. Unplug the coil. Use a remote starter (or a helper) and turn over a few times and notice the stream of gas. It should be robust and may pulse (depending on how fast your engine turns over). If it doesn't, I'd also look at replacing the pump. Careful with the gasoline. It's flammable, you know.
Start with the easiest first, like you are doing, and work from there. Let us know how things work out.
Daniel

2005stangGT

Thanks to everyone who responded. Unfortunately, it was not simply bad gas. I took the car in to Valley Performance in Belleville, NJ yesterday. To make a long story short, there were problems with the carb and the distributor. The vacuum advance was completely non functional, and the distributor could not be "turned" at all to advance the base timing. I guess it was never moved in the last 40 years! Knowing that there was no way this distributor was going to get removed in tact, they recommended changing to an electronic distributor (I believe it was from a 1974 Ford Turino) and ignition module, which we did. Also they did some work adjusting the carb, a needle was gummed up, adjusted air fuel ratio, idle, etc. (The mixture screw on one side of the carb they said was not functioning properly, but to do anything further would take a carb rebuild.) In any event, the car feels like a million dollars compared to how I brought it in. When I brought it down yesterday, it was surging, backfiring, stalling, and hard starting. Now the backfiring is gone, it starts right up, doesn't stall, and has some juice under the hood. It still surges a little, but I didn't expect perfection without them rebuilding the carb completely (which doesn't seem worth it since a 4 barrel is about $300). In any event, this is a place I would definitely take any Mustang to in the future. Eric

BornInAFord

Great to hear your story is resolved.
It's rare these days to find a trusted shop that works on vintage iron.
Daniel