Empty Carb Bowls & Long Starts- ideas to remedy this?

H

hunterhicks

Member

Dec 4, 2003

62

0

7

D/FW

Jun 4, 2008

#1

• Jun 4, 2008

• #1

Howdy all, I have a 65 289 with an Edelbrock 600.
The problem is that the car takes longer and longer to start, proportional to the days it's sat- up to about 4 days, then it takes the same long length to start it (30 seconds)

I posted a little about this before, and D. Hearn was right, the bowls are out of juice.

The gas either evaporates, flows backwards in the fuel system, or of course, it could be the Gas Goblins that roam the quite garage at night...

There are new off-road spring loaded needles in the carb, so I would think it's not flowing backwards.
I don't want to install an electric pump system- too much of a hassle, and this should work fine the way it is

Possibilities:
-The fuel pump is at least 15 years old- I think these are equipped with a one-way valve- might be an issue. maybe not moving enough volume? (seems to work well otherwise)
-there is an inline fuel filter between the pump and carb, but it seems very well connected, and this happened before and after a filter change
-the connection between the hard line from the pump and the rubber fuel line to the carb could be leaking a fraction
-the car loves to run hot (evap the gas)- but it starts fine after 1 day of sitting.
-does gas evaporate on it's own, this quickly, out of a sealed carb somehow?

thanks!

 

ShortThrow50

Member

Oct 22, 2006

923

2

16

Pa

Jun 4, 2008

#2

• Jun 4, 2008

• #2

i dont think thats normal dude. hell my carbed john deere will sit all winter and she will start up within 3 seconds after 5 months of no start. so it cant be that its evaporating, even if it did it still shouldnt take more than just a second or 2 for the bowl to fill while cranking. maybe your gettin to much fuel an flooding out

 

rbohm

Founding Member

Apr 12, 2002

6,698

550

204

tucson,az

Jun 4, 2008

#3

• Jun 4, 2008

• #3

you have fuel either leaking out, or evaporating. evaporation is possible if the float level is set too low.

 

Tony R

New Member

May 29, 2008

102

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0

Vancouver Wa

Jun 4, 2008

#4

• Jun 4, 2008

• #4

I had a car that did the same thing. You had to keep the RPMs up right after you started it or it drained the bowls and you had to prime the car with gas through the carb. Once it warmed up you could take your foot off the gas. I never figured it out.

 

BarnStang

Founding Member

Mar 2, 2001

1,260

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39

Hagerstown, MD

Jun 4, 2008

#5

• Jun 4, 2008

• #5

I know this may not be pratical, but can you scrounge up a carb to borrow and swap it out? It would certanly split the problem into two areas. I would consider that the carb is leaking over a wide area somewhere and evaporating before you see any evidence.

 

G

GNGREN

Member

May 5, 2005

144

3

19

Carroll Valley, PA

Jun 5, 2008

#6

• Jun 5, 2008

• #6

I have the same problem with my 67. I have determined that the fuel is draining back in my situation. I have a clear fuel filter and the fuel will slowly drain out of it. No leaks, and when cranking it takes a few seconds to get fuel to the filter. I know th pump is 16 years old and it was a cheap one when I put it on in High school. Have you checked your pump?

 

P

palerider94

Member

Feb 21, 2006

573

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19

Jun 5, 2008

#7

• Jun 5, 2008

• #7

I'd go with the leaking theory!

 

6

66HertzClone

New Member

Aug 24, 2004

428

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0

Central New Jersey

Jun 5, 2008

#8

• Jun 5, 2008

• #8

It sounds like evaporation to me. You live in an area with a relatively high ambient temperature, there is no evaporative emission equipment on your car. The vents of the fuel bowls are open to the world, very easy over the time given for this to happen.

I don't buy the fuel pump check valve problem, these would be the same valves that pump the fuel to the carb when your engine is running, you've made no mention of it starving for fuel. The fuel inlet to the fuel bowls is not at the bottom of the bowl, if the fuel was draining back down the line, how would it "jump" up to reach the needle valve once its level dropped below full?

Are you using the alcohol enhanced fuel E85? this I would think would evaporate faster than normal gasoline.

You might reduce this some by using an insulator gasket between the carb and the manifold. After the car has been driven and shut off, the temp under the hood will continue to rise for sometime before starting to drop. The fuel in the carb has now been brought to a higher temp which will allow for faster evaporation. This type of gasket would help to control the temp of the fuel in the bowls and slow down the evaporation.

 

Loup-garou

Founding Member

Aug 11, 2001

337

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16

New Orleans, LA

Jun 5, 2008

#9

• Jun 5, 2008

• #9

I concur with 66HertzClone - try a phenolic carburetor spacer and see if the problem diminishes. Remember, the gasoline sold in the D/FW area is E10 - that ethanol content will help to speed evaporation. Add that toasty Dallas weather to the mix and you're likely to see some fuel boil-off, followed by more gradual evaporation after the engine cools. Your comment about the progressive nature of the problem fits this explanation pretty well.

 

G

GNGREN

Member

May 5, 2005

144

3

19

Carroll Valley, PA

Jun 6, 2008

#10

• Jun 6, 2008

• #10

I would still look at the pump personally. I know I can start her up just to annoy the neighbors, shut it down come back in 10 minutes and the filter is dry. No leaks anywhere. But again I know my pump is going. Takes 5-10 seconds to get fuel to the filter when cranking.

 

oz

Founding Member

Jun 29, 2000

1,079

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58

Plymouth, MI

Jun 6, 2008

#11

• Jun 6, 2008

• #11

My 302 w/ Edelbrock 600 does the exact same thing. I can count on a long crank time if it's been more than a couple of weeks. I need to hook up the battery charger every spring to get it primed and running. Once it fires, it runs fine though. I put on a new fuel pump a couple of years ago so I know that's not the problem.
I've always attributed this problem to evaporation. It is a little surprising how long it takes to fill the bowls and get the car fired though.

 

M

mo'factor

Member

Jul 29, 2006

58

0

6

Jun 6, 2008

#12

• Jun 6, 2008

• #12

I have the same problem. I have replaced both the carb and fuel pump with no effect.

 

6

66HertzClone

New Member

Aug 24, 2004

428

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0

Central New Jersey

Jun 6, 2008

#13

• Jun 6, 2008

• #13

GNGREN said:

I would still look at the pump personally. I know I can start her up just to annoy the neighbors, shut it down come back in 10 minutes and the filter is dry. No leaks anywhere. But again I know my pump is going. Takes 5-10 seconds to get fuel to the filter when cranking.

Click to expand...

You could add a check valve to the fuel line somewhere between the pump and the carb. The valves in the fuel pump have to be working correctly, if they were not your fuel pressure would be at or near zero. Both valves in the pump cannot be open at the same time either.

 

BarnStang

Founding Member

Mar 2, 2001

1,260

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Hagerstown, MD

Jun 6, 2008

#14

• Jun 6, 2008

• #14

Didn't someone post in a different thread about this...they suggested that the filler cap was not vented, and the vacuum in the tank could pull the fuel back into the tank? Is that possible? Don't remember what the final answer was in that post...

 

jcode68

Active Member

Jul 15, 2003

892

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Massachussetts

Jun 6, 2008

#15

• Jun 6, 2008

• #15

BarnStang said:

Didn't someone post in a different thread about this...they suggested that the filler cap was not vented, and the vacuum in the tank could pull the fuel back into the tank? Is that possible? Don't remember what the final answer was in that post...

Click to expand...

You may be referring to my post a few weeks ago. The issue was the tank and cap were not vented, which caused a fuel starvation problem after about 10-15 minutes of runtime. I suppose it probably had the same symptom of sucking the gas back down the line due to the vacuum, but at the time that was not the obvious symptom we were seeing and treating. A quick test to rule this out would be to remove your gas cap and see if it drains back down the line like you have been seeing.