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Discussion Starter · #1 ·
I'm trying to get my grandfather's '65 Mustang squared away so he can finally enjoy the car. It has a stock 289 with the only mods being an Edelbrock Performer carb and intake and a Petronix ignition(all installed years ago). It used to fire up every time without fail and run all day long. Now, it will initially start no problem but it refuses to idle and will stall out immediately. If you hold the throttle to keep it alive, it'll stay running but runs rough and stalls as soon as you let off the gas. I raised the idle a bit and kept it alive enough to attempt a test drive but even with heavy throttle in 1st gear it'll buck BAD to the point you're bouncing in the seat and then stall as soon as you let off. The only recent change was replacing the brake booster and master cylinder. I capped off the vacuum line going to the booster just to rule it out and I saw no change.

So far, I've made sure all the butterflies in the carb move(all move), checked the fuel filter(clean), plugged vacuum ports(no change) and tried bumping the idle up(bad idea).
I was going to bring some more tools over next time and check for good spark from the coil, pull some plugs, and take the fuel line off just before the carb and double check for good fuel flow. I was trying to spray for vacuum leaks but it won't idle and runs erratically when you keep it alive that it's hard to tell if it changes anything. Anything else I should be looking at?
Thanks in advance!
 

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Discussion Starter · #5 ·
It's been started up atleast once every week or so.
 

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holley had idle / air bleeds that would cause problems if they got plugged up. a quick blast of air into each passage would sometimes clear up problems.

Not sure how accessible or if edelbrocks even have them or not.
 

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Get this figured out yet?

Bad gas is my guess. If it only runs a very short time 1x/week it's not enough, meaning the gas in the tank is too old. My guess is you'll have to pull the carb, soak it in carb cleaner to clean the deposits/varnish out and then it'll run fine.

I've built hundreds of carbs if not more. Newer ethanol mixed gas does not store well.
 

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carb will have to be fixed... if it can be.... tell me this... was the newer ethanol blend gas ever used in it? if so ... you may have to throw it away. the older stuff is not meant to run that trash ... i dont know why anyone puts that stuff in an older car or truck. i personally have 2 66 mustangs 1 66 ford f150 and a 57 fairlane.. none of them will get this new crap gas in the tanks ever as long as i'm the owner.. screw that stuff.
 

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The carb most certainly needs a rebuild. There is also a good chance that the fuel tank is rusted and needs to be replaced. When I first got my 68 running it would do the same. Turned out I was getting a fine stream of rust particles that would clog the fuel filter and carb. Ended up replacing the fuel tank, fuel lines, filters, fuel pump and rebuilding the carb. I now run only ethanol free fuel and the starts and runs great.

I strongly recommend you head over to the Vintage Mustang Forum. Smart folks here about the newer cars, but the real expertise on the old cars is on VMF.
 

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It's hard to say based on the symptoms. But sometimes I have found that people confuse ignition issues for carb issues. You're basically describing a carb that has a ****ed idle circuit, ****ed main circuit, and maybe ****ed power valve, maybe accelerator pump, as well as maybe clogged air bleeds. How'd all that go wrong at once? Maybe it's not the carb at all. Ignition problems cause your car to run bad in every scenario. I'd do a full ignition tuneup. It's cheap and easy and it sounds like it's been sitting awhile anyway. Then revisit the carb.
 
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