Car dies when stopping

[Stoffauge]

Hello fellows ,

My car 71 sport fury 383 4 bbl stock (carter avs) engine used to run great till yesterday . It left me hanging multiple times.

It runs great on highways but when I am about to stop in the city on roundabouts crossings whatever it dies ! And afterwords it takes like 30sec to restart . All the time when I brake hard/harder and want to stop it dies. Just if hold the trottle a bit and brake with my left foot it keeps running .

What I did when I was back home yesterday night : new Fuel pump I had on the shelf , new pushrod (old one was still at 100% but put in a new hardened one from Hughes anyways . I also changed the fuel filter and you know what came out ?



This dirty coffee like stuff came out the fuel filter . So I changed the filter .

Today in the morning I tested again and it still dies when stopping !

My guess : the carb (was rebuild) is already clogged/dirty. Right/wrong ?
I def do need a new fuel tank because I know that mine is rusted out badly just thought I can handle that dirty stuff with a fuel filter .

What do you guys think ? It runs with good rpm but dies when stopping .(Is there an extra jet for neutral idling or do the main Jets do the job? Because maybe just that one is clogged…)


Hope you’ll say get a new tank rebuild carb again and clean all fuel lines…that would be easy going .

Thanks and cheers

 

[NY69]

Might wanna check your vacuum system; sounds like a vacuum leak to me, especially when it suddenly came up.

 

[Stoffauge]

Might wanna check your vacuum system; sounds like a vacuum leak to me, especially when it suddenly came up.

Sure could be but maybe the filter was clean and car was running good and now after 200miles yesterday it went full/dirty and the issue came up . Remember rusted out tank and thievery dirty fuel out of the filter . I more on the fuel side don’t you think ?

Where would you start looking for a leak ? car runs great when you start it and let it sit and idle…. The process of stopping from like 30miles plus makes it to dies . Not below 30miles and stopping

 

[1970FuryConv]

If dirt has clogged the idle ports of your carb, you might have to compensate for that fuel deprivation with a high idle that engages your main jets.

Dirty spark plugs can force the same thing.

I think the new tank and a new sock on your fuel pickup at the tank are the place to start. New fuel filter is a must. Carb cleaner or fuel treatment might clean out the carb. IOW, I think you are on the right track.

 

[65Port]

Agree on checking vacuum. What is the idle speed? Timing? If you drive it and place into neutral and then stop quickly does it still die? I would also hold off on replacing stuff as that could muddy the waters if the new parts do not resolve it. Good luck

 

[Big_John]

You should do a fuel pressure volume check. Disconnect the fuel line and attach a hose running to a soda bottle, disconnect the coil wire and crank the engine and see if there's a good stream of fuel. That would tell you if there is a fuel delivery issue. One of the best mechanics I ever knew would do that first thing with a problem like this.

I'm betting on dirty carb or the sock on the pickup being clogged.. Or both.

If it's pushing that much crap out, it's time to look at replacing the tank.

 

[CBODY67]

If it runs fine on the carb's "main system" but dies when the "idle system" comes into play, then THAT is where the issue probably is. If the engine starts well when cold, runs well as long as the carb is in the fast idle mode, but dies when it returns to "hot base idle", even while slowing down for a highway exit ramp, but will restart as long as more throttle is used, then that points directily to the carb's idle system being slightly clogged.
gas
Other than the passages in the carb base, where the idle mixture screws are, there is also a "low speed jet" in the base of the solid brass idle feed tubes on the carb's venturi cluster. If those tubes are clogged or restricted, the car will not idle as it should. They can still flow gas through them, but not enough, by observation. Those deposits will not come out with carb cleaner/soak, by observation, as they are "hard deposits".

What I did, after finding the location of the "Low Speed Jet", was to take a bent-wire spark plug gap gauge. I started with the smallest size and worked upward. With the first probe, I felt things break away. Same with the next size, until it could not be inserted any more. Then I went to a hobby shop and got a selection of small twist drills. I went just big enough, progressively, until I "got brass shavings". I then flushed things out with spray carb cleaner and put things back together again. End of problems!

From my experiences,
CBODY67

 

[413]

Car idles on the idle circuit, and it has small passages that are most likely plugged up with that bad fuel you have.

main jets do nothing at idle. But that’s why it runs with your foot on the gas pedal, main metering system working.

start with cleaning out the tank and lines, then clean out the carburetor. No can of miracle cure will help you, it is down to the meat and potatoes here, physically clean out your fuel system.

 

[Stoffauge]

Morning guys . Sorry for my late reply was busy yesterday .

Thanks for all of your effort and input first .

The timing is set with a timing light around 14 degree’s and runs fine .
Car starts and runs fine at idle at around 700rpm and does not die when stopping or braking in neutral if I remember right but I felt very nervous so I always pushed the throttle a little that it def won’t die again .

That the dirty tank has to get replaced I think that is 100% sure .

Will go to the procedure of testing the volume what big John said and will tell you guys soon .

Thanks a lot so far I know there a bit of work coming up but that’s fine

 

[Stoffauge]

You should do a fuel pressure volume check. Disconnect the fuel line and attach a hose running to a soda bottle, disconnect the coil wire and crank the engine and see if there's a good stream of fuel. That would tell you if there is a fuel delivery issue. One of the best mechanics I ever knew would do that first thing with a problem like this.

I'm betting on dirty carb or the sock on the pickup being clogged.. Or both.

If it's pushing that much crap out, it's time to look at replacing the tank.

One simple question : what’s a „good stream“, how do I know if it’s enough?

 

[Big_John]

One simple question : what’s a „good stream“, how do I know if it’s enough?

It's a little subjective. I figure it should fill a 16oz soda bottle about halfway in about 10 secs. That works out to a little over 22 gallons per hour and from what I've read, a stock pump is rated about 25 GPH.

But really, it's more about the strength of the stream. (funny, I just had a talk about this with my urologist yesterday). If it dribbles out, there's something wrong. If it's a strong stream, like turning a faucet on about halfway, then it's good.

 

[rags]

If it runs fine on the carb's "main system" but dies when the "idle system" comes into play, then THAT is where the issue probably is.

take the mixture screws out and shoot some carb. cleaner in the screw holes. easy enough to see if that helps.

What I did, after finding the location of the "Low Speed Jet"

people don't take those into consideration. i use a torch tip cleaner. wasn't afraid to open 'em up a little either.

 

[CBODY67]

take the mixture screws out and shoot some carb. cleaner in the screw holes. easy enough to see if that helps

Woith the idle screws removed, might be able to push the straw from the spray can in far enough to test the fluid flow from each idle needle hole in the throttle body?

CBODY67

 

[rags]

push the straw from the spray can in

exactly what i was thinking. watch them and the transition slots. goal is to open the passages internal and external. not necessarily a permanent solution, but a good 5 minute diagnostic to see if this one thing affects the issue.

 

[Stoffauge]

Great advise with the straw and the carb cleaner! Should I order a new gas tank right away or see if I can solve the problem with all of your advises ? Feel like I should renew the Ristes out one anyways now even if it won’t be the main cause….

 

[rags]

if the tank is rusty and you have the wherewithal, don't hesitate. the fuel tank in my '69 had issues and left me stranded. i'm a cheap f'k and wouldn't replace it. plumbed in a ford fuel injection style fuel filter because they're huge and have a finer filter. did a number of short trips. removed the filter and shook it out regularly until i got clean fuel to come out it. that was in '95. tank and filter are still in it today.

 

[Stoffauge]

if the tank is rusty and you have the wherewithal, don't hesitate. the fuel tank in my '69 had issues and left me stranded. i'm a cheap f'k and wouldn't replace it. plumbed in a ford fuel injection style fuel filter because they're huge and have a finer filter. did a number of short trips. removed the filter and shook it out regularly until i got clean fuel to come out it. that was in '95. tank and filter are still in it today.

May you show me the kind of filter or Got a link ? Don’t wanna spend the 400$ either but feel like it’s the only 100% RIGHT way to never have to think about dirty fuel…

 

[rags]

fram #g3802a. fits 1988 f350 with 460 plus many others. if it will feed a port injected 460, it'll handle 2 4's on a 440 and it does. hooked mine in behind the fuel pump to protect the pump. ends are not barbed but don't have to be. just screw clamp it to seal vacuum. mine with 30 years of crud:

 

[Stoffauge]

Good morning,

I ordered two cans of carb cleaner with straw and will go through all points mentioned and clean the carb and take out the mixture screws etc and will take my time with that. After that I´ll check the flow with the soda bottle test.

I wanna clearly identify the rusted out gas tank and root cause before ordering. Cleanign the carb and checking the volume stream will help getting to that point I feel.

As I really like my classic car to be as most reliable as possible the only right way to go FOR ME might be to buy a new gas tank instead of filtering hundreds of gallons to get all the crap out someday....because I know how it looks from the inside after I did a semi succesful chemical treatment with it on my own at home. Was hoping the best at that day where I put it back in the car

Will keep you updated.

 

[thrashingcows]

With a dirty fuel tank like you seem to have I would recommend installing a simple clear fram G2 filter "before" your fuel pump, then the usual metal canister one after the fuel pump.