Fuel Vaporization Using Eddy Carb -- In-Line Fuel Pump Question

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Lets focus on the problem.

Forget about the inline fuel pump. It's a band aid and wont solve your vapor lock issue.

You need to vent that line which will release the vapor pressure and allow the fuel to flow to the carb which in turn will fill your fuel bowl and thus allow fuel to be pumped to the engine via the carb. Even when it's hot the venting of the vapor continues to allow the fuel to flow. Most VL issues can be solved with the simple mod mentioned above by several people including myself. Having a heat sink on the manifold like a wood or poly spacer plate will also help but venting is the #1 priority here.

If you must install an electric pump then do it properly following the manufacturers installation instuctions. As stated elsewhere in this thread there are many manufacturers and all of them have websites that have instructions you can review before you spend a dime. Below the fuel tank and as close to the tank is the basic rule for location btw.

More homework and less guesswork will solve most of your problems.

Good luck with your project.
 
"The thing" about fuel pumps and "where they are."

All things being equal, IE line routing and fuel pressure, an electric pump IN THE REAR is always going to give less trouble for vapor lock, "why is this?"

It's because even with a clean "free flowing" suction line to an up-front mechanical pump, there is ALWAYS some pressure drop from the tank to the pump.

This is a slight VACUUM, and because it's lower pressure, it LOWERS the boiling point of fuel.

An electric pump helps keep that entire line from the tank to the front of the car UNDER PRESSURE which RAISES the boiling point of fuel and helps prevent boiling and vapor lock.

It's well documented that folks have troubles with Ed carbs, but I don't believe "it's the carb" per se. While it's true that Holley, with the float bowls ABOVE the manifold and with "some" airflow around them, "do better," the FACT is that "in another time" many of us ran AFB, AVS carbs with no problems.

The problem is MODERN FUEL, not the carb
 
lilcuda said:
Here is a two step fix for this and any other Edelbrock carb problem -

Step One - unbolt Edelbrock carb
Step Two - bolt on Holley carb

Problem solved.
Click to expand...

LOL! My thoughts exactly.

(How did people get brainwashed into thinking those Edelbrock carbs were so great anyways?)
 
2 similar problems being confused here. A - when an engine is shut off and carb is hot and fuel boils out of carb. B - when fuel line from tank to mechanical pump is too hot and causes vapor lock. chrysler has a team of engineers and installed the filter between the mechanical pump and carb, some gas monkey had u install filter before pump. please leave filter before pump and buy or borrow a holley and tell us problem still exists
 
Yea try the filter and quit grasping at straws.

I doubt that there is enough residual pressure in a carb system to overcome the vapor lock issue.

Check valves are commonly found in EFI systems where residual pressures are much higher...like 15psi and higher.
 
momoparman said:
Yea try the filter and quit grasping at straws.

I doubt that there is enough residual pressure in a carb system to overcome the vapor lock issue.

Check valves are commonly found in EFI systems where residual pressures are much higher...like 15psi and higher.
Click to expand...

OK, but which filter and where do I put it relative to the pump and proximity of it.
 
Your going to have to do some homework on your own but the filter goes between the pump and the carb wherever you have room for it.

http://www.autopartswarehouse.com/s...3e&c2cid=6bb6e535-1dbf-4413-8434-8e9c40cbadbc


Just type in something like mopar fuel filter for vapor lock and whatever diameter you need and your bound to find many choices. Does not really matter what mfg you use.

Here is one for an older mopar like ours but its 4 times the price. That's why I mention that any filter for carb system will work....you just have to look for one.

http://www.classicindustries.com/product/mopar/parts/mf283.html

Heres a few more part numbers from Wix to help you out.

33040
33041
33050
 
momoparman said:
Your going to have to do some homework on your own but the filter goes between the pump and the carb wherever you have room for it.

http://www.autopartswarehouse.com/s...3e&c2cid=6bb6e535-1dbf-4413-8434-8e9c40cbadbc


Just type in something like mopar fuel filter for vapor lock and whatever diameter you need and your bound to find many choices. Does not really matter what mfg you use.

Here is one for an older mopar like ours but its 4 times the price. That's why I mention that any filter for carb system will work....you just have to look for one.

http://www.classicindustries.com/product/mopar/parts/mf283.html

Heres a few more part numbers from Wix to help you out.

33040
33041
33050
Click to expand...


I like the one on top.
I obviously have to route a tube back to the tank. Sounds either complicated or expense to have done. Yikes. What a hassle. I may just put the inline pump in anyway.
 
cudaracer said:
I like the one on top.
I obviously have to route a tube back to the tank. Sounds either complicated or expense to have done. Yikes. What a hassle. I may just put the inline pump in anyway.
Click to expand...

Yes you need to route a line back to the tank. My question has always been what is the best way to do this if you don't have the extra line from an emissions vehicle?
 
Are you 100% sure the carburetor is having vaporization (vapor lock) issues? Real vapor lock is actually pretty rare. People who think they are experiencing it, are usually having another issue.

I have an Edelbrock 625 on my 75 F250. Stone stock 351M other than a Weiand Action Plus intake. When hot, mine has to spin the engine a bit. I also run the thick insulator gasket. I don't buy the Holley comparison. The fuel bowls are hanging over the intake in either carburetor. I have seen Eddys that pop right off hot. As fantastic as mine runs, I don't give a darn if it takes an extra few seconds to start. Oh and before someone says I don't have enough initial timing, I have it at 20 initial and 35 total, in by 3K. lol I think it's in the carburetor tuning, but I am too lazy to change mine, since it runs so well everywhere else.

I ask if you are sure, because holding the throttle open helps mine. That tells me the idle mixture is a little rich. Have you tried different springs on your metering rods? Have you tried tuning it at all? Usually if you can influence it by holding the throttle open it is too rich. A hot engine doesn't like a rich mixture at startup. Does holding the throttle open help yours?

As good as mine runs, spinning the engine over is nothing to put up with. This thing is also knocking down some high teens in gas mileage. That's a hell of a feat with a 4 speed and 3.73 gears in a truck that has an 8100 pound GVWR rating. As Daddy used to say, "If it ain't broke, don't fix it." LOL
 
Here is what I know for sure. I previously had a clear plastic filter between the pump and carb, and after running the engine to temp, even on a cold day, I could come back in 15 min and that clear filter was bone dry and I would have to turn the starter for 5-6 sec. Happens every time, not just once in a while. Then someone suggested I should put the filter before the pump. So I got a new plastic filter, and put it about 10” before the pump. Nothing changed. I keep thinking I will soon have to replace my starter motor.

And I too question the carb design of a Holley. Does not seem to matter in my case. And that would be an expensive mistake to only have it recur again.
The vent back to the tank kind of makes sense, but I don’t understand the physics of it all to argue against it.
Also,
Mancini Racing out of Michigan claims they sell a lot of the one way switch that has a reservoir that they claim is popular as a fix. Thought I could find it on their website, but I can’t . I have to call back to find out what it is exactly. Anyone ever heard of anything like that?
 
cudaracer said:
Here is what I know for sure. I previously had a clear plastic filter between the pump and carb, and after running the engine to temp, even on a cold day, I could come back in 15 min and that clear filter was bone dry and I would have to turn the starter for 5-6 sec. Happens every time, not just once in a while. Then someone suggested I should put the filter before the pump. So I got a new plastic filter, and put it about 10” before the pump. Nothing changed. I keep thinking I will soon have to replace my starter motor.

And I too question the carb design of a Holley. Does not seem to matter in my case. And that would be an expensive mistake to only have it recur again.
The vent back to the tank kind of makes sense, but I don’t understand the physics of it all to argue against it.
Also,
Mancini Racing out of Michigan claims they sell a lot of the one way switch that has a reservoir that they claim is popular as a fix. Thought I could find it on their website, but I can’t . I have to call back to find out what it is exactly. Anyone ever heard of anything like that?
Click to expand...

Just a thought but check your fuel pump. It should be holding fuel in the filter longer than that.
 
Yes, I have a fuel solenoid on my Ford 8N tractor. Since the fuel tank is on top of the engine, when cut off, the pressure from the fuel can unseat the needle in the carburetor and drain all the gas onto the ground. Since it's an updraft carburetor, it will not fill the engine. But I think that's unnecessary in your situation. You need to find the problem and fix it.

Have you tried another fuel pump? A stock replacement is cheap enough to try to confirm that fuel is not passing back through the pump from the carburetor. That sounds like what is happening. The fuel is not just vaporizing that quickly from the carburetor. No way that much fuel is evaporating. That's a lot of fuel in that float bowl.

How is your fuel filter positioned? If it is vertical, that can pose a problem, as the fuel will tend to run out of the filter easier. I have mine mounted horizontally, on the passenger's side of the carburetor, right above the intake.

Although mine does spin the engine a little when hot, I am nowhere near concerned that it spins enough to hurt the starter, so yours must be much worse. Mine might spin 5 seconds at the worst and that's all. That will never hurt a thing.
 
My old motor did what yours is doing ALL THE TIME and it's damn embarrassing to have to grind and grind, now with my new rebuilt stroker motor I have not had that issue EVER in 3 years so far, but here is what I did different and I have an Edelbrock AVS 650...Carb spacer as mentioned and an air gap manifold. I also have a Holley mechanical fuel pump, metal fuel filter before the pump and edelbrock filter in-line before the carb. braided line from pump to carb. 3/8" SS fuel line no return and vented gas cap....hope this helps..
 
cudaracer said:
Here is what I know for sure. I previously had a clear plastic filter between the pump and carb, and after running the engine to temp, even on a cold day, I could come back in 15 min and that clear filter was bone dry and I would have to turn the starter for 5-6 sec. Happens every time, not just once in a while. Then someone suggested I should put the filter before the pump. So I got a new plastic filter, and put it about 10” before the pump. Nothing changed. I keep thinking I will soon have to replace my starter motor.

And I too question the carb design of a Holley. Does not seem to matter in my case. And that would be an expensive mistake to only have it recur again.
The vent back to the tank kind of makes sense, but I don’t understand the physics of it all to argue against it.
Also,
Mancini Racing out of Michigan claims they sell a lot of the one way switch that has a reservoir that they claim is popular as a fix. Thought I could find it on their website, but I can’t . I have to call back to find out what it is exactly. Anyone ever heard of anything like that?
Click to expand...


Sounds like your tank isn't vented enough and when running the car your building up a vacuum in the tank causing the fuel to be drawn back into the tank from the lines when the engine shuts down. Check you fuel filler cap. If the cap is really old or original, it's worth the $10 for a new one.

Also, I'd like to address the few that are persistent on swapping "the Edelbrock clone" to a Holley. First, The Street Demon carb is not a clone, it is a completely new design. Second, Holley owns Demon Carbs, and has for the last decade, so if your shitting on Demon Carbs, your also shitting on Holley. That is all, thank you!
 
71Scamper said:
Sounds like your tank isn't vented enough and when running the car your building up a vacuum in the tank causing the fuel to be drawn back into the tank from the lines when the engine shuts down. Check you fuel filler cap. If the cap is really old or original, it's worth the $10 for a new one.

Also, I'd like to address the few that are persistent on swapping "the Edelbrock clone" to a Holley. First, The Street Demon carb is not a clone, it is a completely new design. Second, Holley owns Demon Carbs, and has for the last decade, so if your shitting on Demon Carbs, your also shitting on Holley. That is all, thank you!
Click to expand...

This makes sense. I will check the old tired cap I have.
So the vacuum is sucking all that fuel back to the tank. Hmmm.

I also wonder if I have my vacuum canister hooked up right.
 
71Scamper said:
Sounds like your tank isn't vented enough and when running the car your building up a vacuum in the tank causing the fuel to be drawn back into the tank from the lines when the engine shuts down. Check you fuel filler cap. If the cap is really old or original, it's worth the $10 for a new one.

Also, I'd like to address the few that are persistent on swapping "the Edelbrock clone" to a Holley. First, The Street Demon carb is not a clone, it is a completely new design. Second, Holley owns Demon Carbs, and has for the last decade, so if your shitting on Demon Carbs, your also shitting on Holley. That is all, thank you!
Click to expand...

This post makes the most sense. ^^^^^
 
You guys kill me.

I guess welcome back RRR.....that was a short vacation. :D

Good luck cudaracer you'll need it.
 
Something to keep in mind as well. "Vented" gas caps are not just open to the atmosphere all the time. They have a pressure sensitive valve in them. When pressure in the tank exceeds that of the valve, the valve opens and releases said pressure. Technically, older vehicles had what was referred to as a "pressure vacuum" system, quite often that was even written on the fuel cap itself. So it is perfectly normal for the system to have both pressure and vacuum on it at different times.
 
momoparman said:
You guys kill me.

I guess welcome back RRR.....that was a short vacation. :D

Good luck cudaracer you'll need it.
Click to expand...

I don't know what all this means but thanks for the welcome back. If you want to talk about my vacation further, can you post it on the thread I made regarding that, or send me a PM so as not to get this off track? Thanks.
 
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