Percolation? Heat soak? Don't drive during summer??

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DentalDart

DentalDart

FABO Gold Member
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I've been having a fuel problem since I installed a new cam/lifters. At that time the engine/heads were repainted and the engine bay was repainted...

Every time I drive the car it dies on me when its been running for 15-20m and it won't restart for a couple hours. Two times it happened when I took it out and today it happened just idling in the garage. Line from pump wasn't really hot, carb not hot at all, fuel pump wasnt to hot. Really the hottest spot was the line across from the headers on the frame area, but even that I could grab with my bare hands.

When it starts to die it sounds as if it is getting starved for fuel, I try to give it some throttle but even that doesn't stop it from dying.

I changed the fuel line to a steel braided fuel line and added a new edelbrock fuel filter from the auto store ( the one rated for 300hp, might be a little small). Today i replaced the fuel line from the pump to the carb with a stock metal line from right stuff. The carb is a 1yr old AVS2 edelbrock 650 which sits on a 1/2 phenolic spacer.

When I opened the fuel filter up while changing my fuel line today I found a bunch black soot in there.

I know I need to run a return line to the tank for vapors but I'd like to narrow down the problem before just replacing the whole fuel system... If i wasn't paying for 5k in tests this semester and next I would replace everything but I have to try and be cheap right now...

Some pictures. Smoke comes out of the carb when I press the throttle lever at the carb after the car dies.

Any ideas?

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Yeah, it sucks. Hard to fix with headers and a cam. Edelbrock carbs seem to deal with it worse too. I never got mine to stop behaving exactly like yours and it was the number one reason I went to efi.
Replace the fuel filter, should be cheap insurance, but I wouldn't expect it to cure everything.
The "smoke" is fuel vapor from the accelerator pump.

I'd expect non-edelbrock carb to probably work a lot better since plenty of folks drive with carbs still, even in the heat, and don't get stranded every time.. But I have little experience there.
 
Here are the lines from the tank. I don't know if they have ever been replaced.

My fuel guage works just fine, so that shouldn't be a fuel sending unit problem right?

I dont know if my fuel pump has ever been replaced and if it was I don't know when. I have a rubber line that feeds from the metal stock line to the fuel pump, where the line crosses from the frame rail over to the pump.

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Phreakish said:
Yeah, it sucks. Hard to fix with headers and a cam. Edelbrock carbs seem to deal with it worse too. I never got mine to stop behaving exactly like yours and it was the number one reason I went to efi.
Replace the fuel filter, should be cheap insurance, but I wouldn't expect it to cure everything.
The "smoke" is fuel vapor from the accelerator pump.

I'd expect non-edelbrock carb to probably work a lot better since plenty of folks drive with carbs still, even in the heat, and don't get stranded every time.. But I have little experience there.
Click to expand...

Like a holley carb working better? Efi sounds nice in theory, but I barely know how to work the carbs adding electronic stuff might be out of my comfort zone right now... ooh and definitely the 2k price tag to it. Oh and I've forgot to mention, electrical and me are not friends... maybe ill have to learn the electrical when I replace the cars harness...
 
DentalDart said:
Like a holley carb working better? Efi sounds nice in theory, but I barely know how to work the carbs adding electronic stuff might be out of my comfort zone right now... ooh and definitely the 2k price tag to it. Oh and I've forgot to mention, electrical and me are not friends... maybe ill have to learn the electrical when I replace the cars harness...
Click to expand...


What you need is the Cool Carb heat shield. Google it and you’ll find it.

There are two parts to it, but you can just use one. I always use both of them, because it’s relatively cheap.

That carb has issues with heat. I always block the heat crossover in the intake manifold because you don’t need the heat in the first place, and it pisses the carb off in the second place.

That and the Cool Carb heat shield is the best bang for your buck.
 
Hi doc...

When the engine dies you can pump the accelerator and see the accelerator pump squirt fuel into the venturi?

After it dies have you checked for spark?

If it is fuel related you could take some starter fluid and it should fire up.

You should also remove the fuel filler cap right after it dies and see if there is a air rushing sound.

If it is electrical ( what I suspect) things have to cool down to work again. Had a pinto that did that.
 
Last edited:
yellow rose said:
What you need is the Cool Carb heat shield. Google it and you’ll find it.

There are two parts to it, but you can just use one. I always use both of them, because it’s relatively cheap.

That carb has issues with heat. I always block the heat crossover in the intake manifold because you don’t need the heat in the first place, and it pisses the carb off in the second place.

That and the Cool Carb heat shield is the best bang for your buck.
Click to expand...

You think I need a heat shield for the carb, when the carb isnt getting hot? Before I added the spacer it was hot to the touch, now when it dies its cool as can be.

My heat cross over is blocked off as well.

I had this carb on the past year, and never had a problem until I redid the engine and engine bay.
 
yellow rose said:
What you need is the Cool Carb heat shield. Google it and you’ll find it.

There are two parts to it, but you can just use one. I always use both of them, because it’s relatively cheap.

That carb has issues with heat. I always block the heat crossover in the intake manifold because you don’t need the heat in the first place, and it pisses the carb off in the second place.

That and the Cool Carb heat shield is the best bang for your buck.
Click to expand...

I tried every heat shield, spacer, and other gimmicks. None worked and I lived in Vegas at the time too. When it's hot there, it's otherworldly. Plus it's bone dry, so stuff evaporates near instantly.

@DentalDart, I would definitely see if you could borrow a holley style carb from someone and see if it changes much. Other than that, I'm not sure what more you can do.. I was going to add a hood scoop just to help ram more cool air into the engine bay, but went efi before that could happen. I wouldn't recommend efi unless you want to spend a year tinkering after every drive.. It takes a bit to get it tuned in.
 
Have you tried ethanol free gas or an ethanol treatment? Ethanol gas has a lower boiling point than non-ethanol, so it's more susceptible to these issues.
 
if you get fuel vapors from carb after it dies, that makes me think the carb has fuel in it, so not vapor lock. Buy one of those in-line spark checkers(they're like $10), insert it somewhere convenient, and crank it after it stalls and see if it has strong, regular spark. I'm thinking the coil, or pickup or ballast resistor is getting too hot.
 
Dana67Dart said:
Do doc...

When the engine dies you can pump the accelerator and see the accelerator pump squirt fuel into the venturi?

After it dies have you checked for spark?

If it is fuel related you could take some starter fluid and it should fire up.

You should also remove the fuel filler cap right after it dies and see if there is a air rushing sound.

If it is electrical ( what I suspect) things have to cool down to work again. Had a pinto that did that.
Click to expand...

After it died one time I replaced all of my spark plugs and wires... still wouldn't start back up.

When it dies I press the throttle bracket and dont necessary see anything but all the smoke come out of the holes on top of the carb (shown in picture). When it cools down I see lots of fuel go in it.
 
rustycowll69 said:
if you get fuel vapors from carb after it dies, that makes me think the carb has fuel in it, so not vapor lock. Buy one of those in-line spark checkers(they're like $10), insert it somewhere convenient, and crank it after it stalls and see if it has strong, regular spark. I'm thinking the coil, or pickup or ballast resistor is getting too hot.
Click to expand...

Coil or pickup? Damn ballast resistor, I should buy one of those haha. I'll grab one tomorrow at the auto store and switch mine out.
 
RammerJammer75 said:
Have you tried ethanol free gas or an ethanol treatment? Ethanol gas has a lower boiling point than non-ethanol, so it's more susceptible to these issues.
Click to expand...

See reply above. I can buy some ethanol treatment though, if i figure out what it is and what kind to use. :)
 
DentalDart said:
After it died one time I replaced all of my spark plugs and wires... still wouldn't start back up.

When it dies I press the throttle bracket and dont necessary see anything but all the smoke come out of the holes on top of the carb (shown in picture). When it cools down I see lots of fuel go in it.
Click to expand...

Plugs and wires won't help if the issue is the ballast, pickup, or ecm (and heat will often make electronics quit until they cool off).

Same thing: try to borrow a different ecu, or start with that first if you try to replace it. They're tough to test, otherwise I'd suggest that first...
If that doesn't make a difference, return it (or put it in the glove box as a spare) and then try the pickup in the distributor, or at least check and set the gap to the reluctor.
 
DentalDart said:
I only put in gas from chevron, its like 91 or 93 octane. Where do you get non-ethanol gas, from race shop?
Click to expand...

Was hard to find in your neck of the woods. I had heard up by the racetrack there's some places that offer it.

Up here in Hicksville, it's on every corner LOL.
 
DentalDart said:
I only put in gas from chevron, its like 91 or 93 octane. Where do you get non-ethanol gas, from race shop?
Click to expand...

No. From a station whose pump says "NON ETHANOL" printed clearly on it. You can do an online search for stations in your area that have it.
 
Carbs are tricky.
Quick strange story.
I had a brand new Edelbrock carb installed on my most recent BB build.
I was sure I needed the Cool Carb spacer and was all set to get one becsuse It coughed a lot when I jumped on it and the engine ran too hot.
Tried adjusting etc.
Finally brought it to an elder performance mechanic. He said Im sending your carb to my guy to rebuild it, eventhough its "new", he felt it was too lean and couldnt adjust it out.
Great results.
Since then, the car never ran better, no coughing, runs cool, and much more power than before.
So, "new" really doesn't matter.
(I never installed the cool carb spacer).
 
Phreakish said:
Plugs and wires won't help if the issue is the ballast, pickup, or ecm (and heat will often make electronics quit until they cool off).

Same thing: try to borrow a different ecu, or start with that first if you try to replace it. They're tough to test, otherwise I'd suggest that first...
If that doesn't make a difference, return it (or put it in the glove box as a spare) and then try the pickup in the distributor, or at least check and set the gap to the reluctor.
Click to expand...

My distributor is all rebuilt (from a mopar friend here on FABO) new pickup in it too. Ill grab a ballast and yea i need to probably get a new orange box too... I looked at them before, but didn't buy one.
 
DentalDart said:
I've been having a fuel problem since I installed a new cam/lifters. At that time the engine/heads were repainted and the engine bay was repainted...

Every time I drive the car it dies on me when its been running for 15-20m and it won't restart for a couple hours. Two times it happened when I took it out and today it happened just idling in the garage. Line from pump wasn't really hot, carb not hot at all, fuel pump wasnt to hot. Really the hottest spot was the line across from the headers on the frame area, but even that I could grab with my bare hands.

When it starts to die it sounds as if it is getting starved for fuel, I try to give it some throttle but even that doesn't stop it from dying.

I changed the fuel line to a steel braided fuel line and added a new edelbrock fuel filter from the auto store ( the one rated for 300hp, might be a little small). Today i replaced the fuel line from the pump to the carb with a stock metal line from right stuff. The carb is a 1yr old AVS2 edelbrock 650 which sits on a 1/2 phenolic spacer.

When I opened the fuel filter up while changing my fuel line today I found a bunch black soot in there.

I know I need to run a return line to the tank for vapors but I'd like to narrow down the problem before just replacing the whole fuel system... If i wasn't paying for 5k in tests this semester and next I would replace everything but I have to try and be cheap right now...

Some pictures. Smoke comes out of the carb when I press the throttle lever at the carb after the car dies.

Any ideas?

View attachment 1715598579

View attachment 1715598580

View attachment 1715598581

View attachment 1715598582
Click to expand...
What is the fuel pressure at the carb?
May be a weak fuel pump when it gets hot
 
Dana67Dart said:
Could be that the paint is creating a bad grounding situation.
Click to expand...

The paint created a bad ground on the engine from the battery, i had to sand it off at that spot and havent had a problem since. If its cool it fires right up no problem. After sitting a couple of weeks it takes a bit of cranking to prime the system and it fires right up.
 
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