340 Stalling Hot???

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shhnappa

shhnappa

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OK, I've got a 340 in a '68 Cuda, Mopar electronic dist, orange box, mild cam, timing is fine, vac. is fine, don't know what my fuel pressure is, but its a stock fuel pump, and fuel lines are in the factory locations. The car starts and runs great from a cold start all they way up to about an hour and a half of driving. Once everything gets hot (under the hood), temp running at 190*, she starts to stumble sitting at a light, then stalls as I start give it throttle pulling away from a light, then extreamly hard starting, pumping the gas to get it going, and almost have to neutral drop it to keep her running. I did install the Edlebrock black spacer plate (3/4") under my Edlebrock 1406 carb last year thinking it was a fuel boil situation, and thought I had it licked, but I guess I never drove it long enough in the hot weather for it to happen. I'm looking for any suggesions, I can't really tell if its fuel or spark, but I'm thinking its fuel because I have to pump the crap out of the gas to get her started again. I was thinking to replace the orange box with the chrome one, but don't want to just throw money at it. Let me know what you guys think.
 
I Had The Same Problem With A 318. Tried Everything, Finally Changed Orange Box And Never Had The Problem Again. Good Luck And Let Us Know....topnotch66
 
Did you tune the carb? Setting idle mix and speed is only touching the surface. Sounds like the step up springs are a hair too stiff. You need to know your vacuum both at idle, and under driving comditions like light throttle and cruise.
 
Install a vacuum gauge in the car. I have one in my '70 Duster and it's awesome being able to see exactly what the engine is feeling like.
 
topnotch66 said:
I Had The Same Problem With A 318. Tried Everything, Finally Changed Orange Box And Never Had The Problem Again. Good Luck And Let Us Know....topnotch66
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I would suggest this also or the ballast resistor.
 
MACKIN said:
I would suggest this also or the ballast resistor.
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I forgot to mention this (it was so long ago). When I got the car 8 months ago, I went to hook up a Tach in the dash, I noticed that the coil was wired backwards, but it ran. I switched the wires from + to - and visa versa and she still ran the same, could this have caused damage to my coil, which may be happening when hot?
 
I just went through the same exact thing. If you have a fuel pressure gauge or a clear fuel filter(so you can see if it not getting fuel) it will help you find out if the problem is fuel related. I would loose pressure and also my filter would slowly go dry AFTER the motor got hot.... ran perfect until it got hot. The car stalled on me a few times so I started looking to find the problem. I cranked the car up and let it idle until something happened... sure enough it happened. The first thing that happened was my fuel pressure started to fall then bubbles started to pop up from the fuel pump side in the clear filter. Then the fuel pressure fell to 4 psi and then motor started going lean. What I found was my fuel line was not ran properly and was causing vapor lock situation.
 
mullinax95 said:
I just went through the same exact thing. If you have a fuel pressure gauge or a clear fuel filter(so you can see if it not getting fuel) it will help you find out if the problem is fuel related. I would loose pressure and also my filter would slowly go dry AFTER the motor got hot.... ran perfect until it got hot. The car stalled on me a few times so I started looking to find the problem. I cranked the car up and let it idle until something happened... sure enough it happened. The first thing that happened was my fuel pressure started to fall then bubbles started to pop up from the fuel pump side in the clear filter. Then the fuel pressure fell to 4 psi and then motor started going lean. What I found was my fuel line was not ran properly and was causing vapor lock situation.
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Too funny, I read your entire thread on Sunday, and ran out to my car to see where my fuel line was running, and sure enough, it's at the factory location, I was so hopeful, then let down. If you look at my first post, I made sure to note "fuel lines are in the factory locations", because of your post, I wish it was that simple. Anyway, I just picked up a carb rebuild kit, new fuel line that will incorporate a pressure guage, so at least once I get her back together, I'll be able to monitor line pressure when she starts to crap out. Thanks for the reply LOL...
 
shhnappa said:
Too funny, I read your entire thread on Sunday, and ran out to my car to see where my fuel line was running, and sure enough, it's at the factory location, I was so hopeful, then let down. If you look at my first post, I made sure to note "fuel lines are in the factory locations", because of your post, I wish it was that simple. Anyway, I just picked up a carb rebuild kit, new fuel line that will incorporate a pressure guage, so at least once I get her back together, I'll be able to monitor line pressure when she starts to crap out. Thanks for the reply LOL...
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Oh... you saw my thread. lol

Do you have a pressure gauge or clear filter?

Does the motor seem like it is running out of gas or BAM! shuts right off?

I would recommend makeing sure you have the same fuel pressure at all times... hot or cold.
 
im going thru the exact same thing as you are right now and im running the same carb as you r. let me know how it turns out. :toothy10:
 
Have you checked inside the carb? I would pull the mixture screws out and use a blow gun to pump some air through it. also pull the top off and check the float setting and pull the needle and seat to see if they are clean. how is the choke operating too, does it open all the way when it warms up?
 
I ran into that problem a few years ago stalling in hot weather especially at a stop light. I installed an electric fuel pump near the tank pickup area. Problem solved. BTW I used an inexpensive carter unit no regulator required. and thats why modern day cars don't usually have a vapor lock problem.
 
I had the exact same problem changed carb, orange box,dist,checked fuel presh. turned out to be the yellow accel coil. It idles way smoother and hasent stalled since.
 
The Orange Box is known to be a hunk of crap. Newer ones anyway..... We had a big thread on the "downhill" quality control on these a long time ago.

Even if it is not the cause of you problems, I would think twice about running one.
 
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