Stalls after stopping

[Vaughn]

Any help would be greatly appreciated.

 

1970 Monte, 350, 4 barrel Qjet carb

 

Starts, idles, runs great.

 

My problem is the car runs great, cruising down the highway at 60mph, 3000rpm, no problem, 70mph at 3500rpm, no problem......but if I pull over and let it idle for a minute or two and then go to accelerate the car bogs down and stalls. It will fire up again after a few turns of the starter and then run fine again.

 

Is it a problem with the float setting???

 

Thank you in advance

[Mo's70MCs]

sounds like it.. will it stay idling or eventually start to stumble and die, coming to a quick stop and dying and or a quick turn.

[stangeba]

Could be some junk in the float needle and seat causing it to flood at idle.

[Vaughn]

Coming to a quick stop, idles fine, no stumbling until I try and press on the pedal, then it stumbles. This is only at full engine temperature, not when cold.

[stangeba]

Perhaps the accelerator is not squirting properly on light throttle.

With the engine off, remove the air cleaner, open the choke (if it isn't) look down the primary throttle bores while lightly moving the accelerator open, to see if your pump shot is strong, weak on one side or both are very weak or just dribbling. Could be plugged or partially plugged with some sort of debris or the rubber on the pump is dry and hard.

Good luck.

[Vaughn]

Thanks Bruce I will check that today

[Leghome]

Could be sucking air somewhere. My 72 did that when I got it 5 years ago and we found that the base of the Holley carb was bent. replaced the carb and no problem since. If you feathered it it worked fine but under hard acceleration it stumbled every time. Vacuum leak could also cause the same thing. 

[Vaughn]

It appears that the pump shot is strong or good enough.

 

I cant find any vacuum leaks

 

Any other ideas that I could try???

 

Thanks

[stangeba]

It has this problem today but last .... month it didn't?

Has anything changed? 

Did you, change (or even touch) the dist, points, wires, plugs, cap, rotor, air cleaner, anything?

Did anyone else take it for a ride :-)

What about the power valve guys? I have never heard of them going bad in a Quadrajet.

Secondaries opening too quickly, the choke pull off diaphragm leaking or unhooked?

That's it from me, I think I would pull off the top of the carb and look inside to see if it's all gummed up.

[wallaby]

_{This is a tough one. As I picture the event, it's like you are just fine cruising the highway, but when you exit it gives trouble at the next stoplight?}

_{Does the problem show up at every stoplight thereafter? Is it going to die every time, or is there some driver input that will keep it going? Does it idle ok at the stoplight, but only gives issue when the light turn green?}

 

_{My first reaction would be to check the internal fuel filter of the carb. They are kind of a pain to get to, so they tend to go un-serviced.}

_{Try a full throttle run from a slow speed up till she shifts into third. If it handles that without issue, you can figure the filter is ok.}

[stangeba]

I said I was finished but.......

I remember my idle would not return to the same RPM after I would rev it due to badly worn out throttle shaft bushings.

With the engine off, I would push on the shaft and could see the movement up and down and ft to back it was so worn out.

I sent it to someone about 20 years ago to have it repaired and re-colored. Turned out great!

I am a strong advocate of NEVER turning in an original OEM part in exchange for a junk rebuilt carb (or alternator or starter)

Have what you have rebuilt unless it's wrong anyway.

Verify with the part number on the carb.

Bruce

[Vaughn]

Thanks for the replies,

 

Car was fully restored about three years ago. Original carb was rebuilt. Here is one thing that might be an issue, the car did sit for a year. Started and ran to temp a few times but never out on the road till last weekend. When the problem started.

 

Car idles great after stopping, but if I push the throttle it wants to stall and sometimes will, back off the throttle and it will not stall. Almost a fuel starvation problem. If it does stall, it will take 10 seconds or so to fire up again but then runs great.

Going to check a few things you all have mentioned tonight. Top off carb, fuel filter etc. Will be taking the Monte for a cruise and car show tomorrow.

See if I can narrow this down.

[Sam (Bones)]

sounds like the float is sticking closed, it has enough fuel to idle, but that's about it, carb might have gotten gummed up a little from sitting

[58impala]

Could it be vapor lock, maybe fuel line is too close to exhaust somewhere along the line?

[Vaughn]

Thanks for the help guys, really appreciate the ideas.

 

I replaced the fuel filter and adjusted the float a little. Drove the car 150 miles over a two day period this weekend and no issues. In hind site I think it was from the car sitting and things got a little gummed up.